Document and Entity Information	12 Months Ended
Document and Entity Information	Dec. 31, 2011
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Trading Symbol	BIDU
Entity Registrant Name	Baidu, Inc.
Entity Central Index Key	0001329099
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Class A Ordinary Shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding	27,111,117
Class B Ordinary Shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding	7,803,000

CONSOLIDATED BALANCE SHEETS In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY	Dec. 31, 2011 Class A Ordinary Shares USD ($)	Dec. 31, 2011 Class A Ordinary Shares CNY	Dec. 31, 2010 Class A Ordinary Shares CNY	Dec. 31, 2011 Class B Ordinary Shares USD ($)	Dec. 31, 2011 Class B Ordinary Shares CNY	Dec. 31, 2010 Class B Ordinary Shares CNY
Current assets:
Cash and cash equivalents	$ 655,791	4,127,482	7,781,976
Restricted cash	76,803	483,387	38,278
Short-term investments	1,597,035	10,051,578	376,492
Accounts receivable, net of allowance of RMB2,223 for 2010 and RMB5,806 (US$922) for 2011	95,260	599,558	296,900
Due from related parties	23,790	149,728	98,660
Deferred tax assets, net	19,290	121,411	86,487
Other assets, current	50,050	315,012	103,654
Total current assets	2,518,019	15,848,156	8,782,447
Non-current assets:
Fixed assets, net	436,016	2,744,241	1,622,412
Intangible assets, net	147,525	928,511	115,798
Goodwill	384,427	2,419,542	63,686
Long-term investments, net	116,678	734,360	287,968
Due from related parties	15,888	100,000	0
Deferred tax assets, net	8,282	52,125	30,843
Other assets, non-current	81,604	513,606	145,285
Total non-current assets	1,190,420	7,492,385	2,265,992
Total assets	3,708,439	23,340,541	11,048,439
Current liabilities:
Short-term loans	20,000	125,878	0
Accounts payable and accrued liabilities	404,430	2,545,445	1,317,771
Customer advances and deposits	250,078	1,573,967	1,029,344
Deferred revenue	9,963	62,705	109,032
Deferred income	5,526	34,779	0
Due to related parties	0	0	95,700
Long-term loans, current portion	7,309	46,000	0
Capital lease obligation	2,824	17,773	0
Total current liabilities	700,130	4,406,547	2,551,847
Non-current liabilities:
Deferred income	3,168	19,942	5,000
Long-term loans	361,926	2,277,925	86,000
Due to related parties	23,654	148,873	0
Deferred tax liabilities	20,914	131,629	0
Capital lease obligation	4,784	30,112	0
Total non-current liabilities	414,446	2,608,481	91,000
Total liabilities	1,114,576	7,015,028	2,642,847
Commitments and contingencies
Redeemable noncontrolling interests	148,712	935,978	0
Equity
Additional paid-in capital	281,505	1,771,770	1,557,258
Retained earnings	2,161,511	13,604,334	6,965,697
Accumulated other comprehensive loss	(13,410)	(84,403)	(117,378)
Total Baidu, Inc. shareholders' equity	2,429,608	15,291,716	8,405,592
Ordinary shares, value				2	12	12	0	3	3
Noncontrolling interests	15,543	97,819	0
Total equity	2,445,151	15,389,535	8,405,592
Total liabilities and equity	$ 3,708,439	23,340,541	11,048,439

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Common stock, par value per share	$ 0.00005	$ 0.00005
Common stock, shares authorized	870,400,000	870,400,000
Class A Ordinary Shares
Common stock, par value per share	$ 0.00005	$ 0.00005
Common stock, shares authorized	825,000,000	825,000,000
Common stock, shares issued	27,111,117	27,045,340
Common stock, shares outstanding	27,111,117	27,045,340
Class B Ordinary Shares
Common stock, par value per share	$ 0.00005	$ 0.00005
Common stock, shares authorized	35,400,000	35,400,000
Common stock, shares issued	7,803,000	7,804,332
Common stock, shares outstanding	7,803,000	7,804,332

Total number of shares of common stock held by shareholders. May be all or portion of the number of common shares authorized. These shares represent the ownership interest of the common shareholders. Shares outstanding equals shares issued minus shares held in treasury and other adjustments, if any.

+ References+ Details

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY	Dec. 31, 2009 CNY	Dec. 31, 2011 Common Class A and Class B USD ($)	Dec. 31, 2011 Common Class A and Class B CNY	Dec. 31, 2010 Common Class A and Class B CNY	Dec. 31, 2009 Common Class A and Class B CNY
Revenues:
Online marketing services	$ 2,302,192	14,489,767	7,912,869	4,445,310
Other services	1,751	11,019	2,205	2,466
Total revenues	2,303,943	14,500,786	7,915,074	4,447,776
Operating costs and expenses:
Cost of revenues	(619,153)	(3,896,883)	(2,149,288)	(1,616,236)
Selling, general and administrative	(268,961)	(1,692,810)	(1,088,980)	(803,988)
Research and development	(212,020)	(1,334,434)	(718,038)	(422,615)
Total operating costs and expenses	(1,100,134)	(6,924,127)	(3,956,306)	(2,842,839)
Operating profit	1,203,809	7,576,659	3,958,768	1,604,937
Other income:
Interest income, net	53,329	335,650	67,121	32,661
Foreign exchange (loss) gain, net	(311)	(1,959)	6	(42)
Loss from equity method investments	(28,505)	(179,408)	(8,965)	(229)
Other income, net	12,431	78,237	44,233	45,794
Total other income	36,944	232,520	102,395	78,184
Income before income taxes	1,240,753	7,809,179	4,061,163	1,683,121
Income taxes	(188,891)	(1,188,861)	(535,995)	(198,017)
Net income	1,051,862	6,620,318	3,525,168	1,485,104
Net loss attributable to noncontrolling interests	(2,911)	(18,319)	0	0
Net income attributable to Baidu, Inc.	1,054,773	6,638,637	3,525,168	1,485,104
Earnings per share for Class A and Class B ordinary shares:
Net income attributable to Baidu, Inc. -Basic					$ 30.23	190.27	101.28	42.96
Net income attributable to Baidu, Inc. -Diluted					$ 30.17	189.88	100.96	42.70
Earnings per ADS (1 Class A ordinary share equals 10 ADSs):
Net income attributable to Baidu, Inc. -Basic					$ 30.23	190.27	101.28	42.96
Net income attributable to Baidu, Inc. -Diluted					$ 30.17	189.88	100.96	42.70
Weighted average number of Class A and Class B ordinary shares outstanding
Basic					34,890,050	34,890,050	34,805,362	34,570,790
Diluted					34,962,831	34,962,831	34,917,835	34,776,366
Other comprehensive income (loss), net of tax
Foreign currency translation adjustment	5,233	32,930	(3,611)	(3,961)
Unrealized gains on available-for-sale securities	7	45	0	0
Other comprehensive income (loss), net of tax	5,240	32,975	(3,611)	(3,961)
Comprehensive income	1,057,102	6,653,293	3,521,557	1,481,143
Comprehensive loss attributable to noncontrolling interests	(3,069)	(19,314)	0	0
Comprehensive income attributable to Baidu, Inc.	$ 1,060,171	6,672,607	3,521,557	1,481,143

CONSOLIDATED STATEMENTS OF CASH FLOWS In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY	Dec. 31, 2009 CNY
Cash flows from operating activities:
Net income	$ 1,051,862	6,620,318	3,525,168	1,485,104
Adjustments to reconcile net income to net cash generated from operating activities:
Depreciation of fixed assets and others	130,164	819,239	431,099	306,281
Fixed assets written off	5	31	7,679	2,606
Amortization of intangible assets	10,434	65,673	10,252	10,729
Deferred income tax, net	(10,280)	(64,701)	(74,374)	(10,839)
Share-based compensation	24,155	152,028	93,736	86,318
Provision (reversal) for doubtful accounts	556	3,500	(6,940)	493
Gain on investments, net	(31,810)	(200,209)	(41,193)	(8,181)
Impairment on long-term investments	7,608	47,886	0	0
Loss from equity method investments	28,505	179,408	8,965	229
Other noncash income	(5,848)	(36,813)	0	0
Changes in operating assets and liabilities net of effects of acquisition:
Restricted cash	(24,821)	(156,219)	(18,765)	(14,951)
Accounts receivable	(44,879)	(282,467)	(128,307)	(69,331)
Other assets	(33,639)	(211,719)	(28,560)	5,752
Due from related parties	(24,002)	(151,068)	(98,660)	10,697
Customer advances and deposits	82,574	519,716	421,516	185,302
Accounts payable and accrued liabilities	129,911	817,649	431,168	236,012
Deferred revenue	(7,360)	(46,327)	66,997	38,595
Deferred income	7,900	49,721	5,000	(332)
Due to related parties	8,448	53,173	95,700	0
Net cash generated from operating activities	1,299,483	8,178,819	4,700,481	2,264,484
Cash flows from investing activities:
Acquisition of fixed assets	(279,972)	(1,762,114)	(895,309)	(399,312)
Disposal of fixed assets	391	2,461	0	0
Acquisition of businesses	(309,167)	(1,945,870)	0	(12,000)
Acquisition of intangible assets	(68,891)	(433,591)	(2,452)	0
Capitalization of software costs	(6,782)	(42,687)	(10,179)	(11,392)
Purchases of long-term investments	(77,679)	(488,905)	(282,932)	(2,250)
Disposal of long-term investments	1,914	12,047	0	0
Purchases of short-term investments	(1,743,398)	(10,972,774)	(2,620,265)	(779,676)
Sales and maturities of short-term investments	235,937	1,484,968	2,661,794	707,929
Acquisition of long-term prepaid computer parts	(16,534)	(104,064)	(68,179)	(39,368)
Net cash used in investing activities	(2,264,181)	(14,250,529)	(1,217,522)	(536,069)
Cash flows from financing activities:
Capital injection of noncontrolling interests holders	6,986	43,970	0	0
Proceeds from short-term debt	20,000	125,878	0	0
Proceeds from long-term debt	354,753	2,232,778	86,000	0
Proceeds from exercise of share options	3,683	23,184	38,751	40,442
Structured share repurchase, net	0	0	0	79,070
Repurchase of ordinary shares	0	0	0	(24,419)
Net cash generated from financing activities	385,422	2,425,810	124,751	95,093
Effect of exchange rate changes on cash and cash equivalents	(1,364)	(8,594)	(6,110)	(741)
Net increase (decrease) in cash and cash equivalents	(580,640)	(3,654,494)	3,601,600	1,822,767
Cash and cash equivalents at beginning of the year	1,236,431	7,781,976	4,180,376	2,357,609
Cash and cash equivalents at end of the year	655,791	4,127,482	7,781,976	4,180,376
Supplemental disclosures:
Interest paid	2,784	17,521	709	0
Income taxes paid	185,134	1,165,218	436,632	150,170
Non-cash investing activities:
Capital lease obligation	7,608	47,885	0	0
Acquisition of fixed assets included in accounts payable and accrued liabilities	39,053	245,794	248,540	139,038
Acquisition of other non-current assets included in accounts payable and accrued liabilities	4,916	30,938	29,130	5,176
Non-cash acquisitions of investments	$ 30,869	194,286	3,982	0

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY In Thousands, except Share data	Total USD ($)	Total CNY	Ordinary Shares USD ($)	Ordinary Shares CNY	Additional Paid-in Capital USD ($)	Additional Paid-in Capital CNY	Retained Earnings USD ($)	Retained Earnings CNY	Accumulated Other Comprehensive Loss USD ($)	Accumulated Other Comprehensive Loss CNY	Noncontrolling interests USD ($)	Noncontrolling interests CNY
Balance at Dec. 31, 2008		3,088,663		15		1,218,356		1,979,844		(109,552)		0
Balance (in shares) at Dec. 31, 2008				34,515,833
Net income		1,485,104						1,485,104
Other comprehensive income		(3,961)								(3,961)
Exercise of share-based awards (in shares)				270,199
Exercise of share-based awards		41,121				41,121
Share-based compensation		87,523				87,523
Structured share repurchase		79,070				79,070
Repurchase of ordinary shares (in shares)				(32,740)
Repurchase of ordinary shares		(24,419)						(24,419)
Balance at Dec. 31, 2009		4,753,101		15		1,426,070		3,440,529		(113,513)		0
Balance (in shares) at Dec. 31, 2009				34,753,292
Net income		3,525,168						3,525,168
Other comprehensive income		(3,611)				254				(3,865)
Exercise of share-based awards (in shares)				96,380
Exercise of share-based awards		36,819				36,819
Share-based compensation		94,115				94,115
Balance at Dec. 31, 2010		8,405,592		15		1,557,258		6,965,697		(117,378)		0
Balance (in shares) at Dec. 31, 2010				34,849,672
Net income		6,630,602						6,638,637				(8,035)
Other comprehensive income	5,240	32,975								32,975
Exercise of share-based awards (in shares)			64,445	64,445
Exercise of share-based awards		25,553				25,553
Share-based compensation		148,575				148,575
Business combination		104,832										104,832
Equity issuance of subsidiaries		41,406				40,384						1,022
Balance at Dec. 31, 2011	$ 2,445,151	15,389,535	$ 2	15	$ 281,505	1,771,770	$ 2,161,511	13,604,334	$ (13,410)	(84,403)	$ 15,543	97,819
Balance (in shares) at Dec. 31, 2011			34,914,117

ORGANIZATION, CONSOLIDATION AND PRESENTATION OF FINANCIAL STATEMENTS

12 Months Ended

Dec. 31, 2011

ORGANIZATION, CONSOLIDATION AND PRESENTATION OF FINANCIAL STATEMENTS

1.	ORGANIZATION, CONSOLIDATION AND PRESENTATION OF FINANCIAL STATEMENTS

Baidu, Inc. (“Baidu” or the “Company”) was incorporated under the laws of the Cayman Islands on January 18, 2000. The Company is the sole shareholder of Baidu Holdings Ltd. (“Baidu Holdings”) incorporated in the British Virgin Islands.

As of December 31, 2011, Baidu Holdings owns the following wholly-owned subsidiaries:

•

Baidu Online Network Technology (Beijing) Co., Ltd. (“Baidu Online”) incorporated under the laws of the People’s Republic of China (“PRC”) on January 18, 2000,

•

Baidu Japan Inc. (“Baidu Japan”) incorporated under the laws of Japan on December 13, 2006,

•

Baidu (Hong Kong) Limited (“Baidu HK”) incorporated under the laws of Hong Kong on November 27, 2007, and

•

Baidu International Technology (Shenzhen) Co., Ltd. (“Baidu International”) incorporated under the laws of the PRC on November 23, 2010.

As of December 31, 2011, Baidu Holdings owns the following majority-owned subsidiaries:

•

B.D. Mobile Telecommunication Limited(“B.D. Mobile”) incorporated under the laws of Cayman Islands on January 25, 2011, and

•

Qunar Cayman Islands Limited (“Qunar”) incorporated under the laws of the Cayman Islands and acquired by Baidu Holdings on July 20, 2011.

Baidu HK owns the following wholly-owned subsidiaries in the PRC:

•

Baidu (China) Co., Ltd. (“Baidu China”) incorporated under the laws of the PRC on June 6, 2005, and

•

Baidu.com Times Technology (Beijing) Co., Ltd. (“Baidu Times”) incorporated under the laws of the PRC on April 19, 2006.

Baidu Japan has established the following wholly-owned subsidiaries in Japan and the United States of America (“USA”):

•

Hyakudo Inc. (“Hyakudo”) incorporated under the laws of Japan on April 14, 2008,

•

Baido, Inc. (“Baido”) incorporated under the laws of Japan on April 14, 2008, and

•

Baidu USA LLC incorporated under the laws of the USA on November 12, 2010.

As of December 31, 2011, the Company also effectively controls the following variable interest entities (“VIE”) through Baidu Online:

•

Beijing Baidu Netcom Science Technology Co., Ltd. (“Baidu Netcom”) incorporated under the laws of the PRC on June 5, 2001,

•

Beijing Perusal Technology Co., Ltd. (“Beijing Perusal”) incorporated under the laws of the PRC on June 6, 2006,

•

Beijing BaiduPay Science and Technology Co., Ltd. (“BaiduPay”) incorporated under the laws of the PRC on February 27, 2008, and

•

Baidu HR Consulting (Shanghai) Co., Ltd. (“Baidu HR”) incorporated under the laws of the PRC on December 28, 2010.

Furthermore, Baidu Netcom acquired Beijing Founder Network Technology Co., Ltd. on November 25, 2011.

The Company, its wholly-owned and majority-owned subsidiaries and VIEs are hereinafter collectively referred to as the “Group.” The Group offers Internet search solutions and online marketing solutions, operates an e-commerce online payment platform which enables customers to make payments online, develops and markets scalable web application software and provides related services, as well as provides human resource related services including employment agency services. The Group’s principal geographic market is in the PRC and Japan. The Company does not conduct any substantive operations of its own but conducts its primary business operations through its wholly-owned and majority-owned subsidiaries and VIEs in the PRC.

PRC laws and regulations prohibit or restrict foreign ownership of Internet content, advertising and employment agency businesses. To comply with these foreign ownership restrictions, the Group operates its websites and primarily provides online advertising services in the PRC through VIEs, the PRC legal entities that were established by the individuals authorized by the Group. The paid-in capital of the VIEs was funded by the Group through loans extended to the authorized individuals. The Group has entered into certain exclusive agreements with the VIEs through Baidu Online and certain other subsidiaries (collectively the “Primary Beneficiaries”), which obligate the Primary Beneficiaries to absorb a majority of the risk of loss from the VIEs’ activities and entitles the Primary Beneficiaries to receive a majority of their residual returns. In addition, the Group has entered into certain agreements with the authorized individuals through the Primary Beneficiaries, including loan agreements for the paid-in capital of the VIEs, option agreements to acquire the equity interests in the VIEs when permitted by the PRC laws, and share pledge agreements for the equity interests in the VIEs held by the authorized individuals.

Despite the lack of technical majority ownership, there exists a parent-subsidiary relationship between the Company and VIEs through certain agreements with the authorized individuals through the Primary Beneficiaries, including loan agreements for the paid-in capital of the VIEs, option agreements to acquire the equity interests in the VIEs when permitted by the PRC laws, and share pledge agreements for the equity interests in the VIEs held by the authorized individuals. The shareholders of VIEs, who are the authorized individuals except for two noncontrolling shareholders of Baidu HR (shareholders of VIEs mentioned hereinafter only refer to those authorized individuals), effectively assigned all of their voting rights underlying their equity interest in VIEs to the Primary Beneficiaries. In addition, through the other aforementioned agreements, the Company, through the Primary Beneficiaries, demonstrates its ability and intention to continue to exercise the ability to absorb substantially all of the profits and all of the expected losses of VIEs. The VIEs are subject to operating risks, which determine the variability of the Company’s interest in those entities. Based on these contractual arrangements, the Company consolidates the VIEs as required by Accounting Standards Codification (“ASC”) subtopic 810-10 (“ASC 810-10”), Consolidation: Overall, because the Company holds all the variable interests of VIEs through the Primary Beneficiaries.

The principal terms of the agreements entered into between Primary Beneficiaries, VIEs and their respective shareholders are further described below:

Loan Agreements

Pursuant to loan agreements amongst the shareholders of Baidu Netcom and Baidu Online, Baidu Online provided interest-free loans with an aggregate amount of RMB100 million to the shareholders of Baidu Netcom solely for the latter to fund the capitalization of Baidu Netcom. The loans can be repaid only with the proceeds from sale of the shareholders’ equity interest in Baidu Netcom to Baidu Online or its designated person. The term of the loan agreements will expire on April 26, 2014 and can be extended with the written consent of both parties before its expiration.

Each of the loan agreements amongst Baidu Online and the respective shareholders of Beijing Perusal, BaiduPay and Baidu HR contains the same terms as those described above, except that the amount of the loans extended to the respective shareholders is RMB1.0 million, RMB 9.0 million, and RMB50.0 million, respectively. The term of the loan agreements will expire on May 18, 2016, April 26, 2020, and December 27, 2020, respectively, and can be extended with the written consent of both parties before its expiration.

Exclusive Equity Purchase Option Agreement

Pursuant to the exclusive equity purchase option agreement amongst the shareholders of Baidu Netcom, Baidu Netcom and Baidu Online, the shareholders of Baidu Netcom irrevocably granted Baidu Online or its designated person(s) an exclusive option to purchase, to the extent permitted under PRC law, all or part of the equity interests in Baidu Netcom for the cost of the initial contributions to the registered capital or the minimum amount of consideration permitted by applicable PRC law. The shareholders should remit to Baidu Online any amount that is paid by Baidu Online or its designated person in connection with the purchased equity interest. Baidu Online or its designated person has sole discretion to decide when to exercise the option, whether in part or in full. Any and all dividends and other capital distributions from Baidu Netcom to its shareholders should be paid to Baidu Online in full amount. Baidu Online would provide unlimited financial support to Baidu Netcom, if in the normal operation of business, Baidu Netcom would become in need of any form of reasonable financial support. If Baidu Netcom were to incur any loss and as a result cannot repay any loans from Baidu Online, Baidu Online should unconditionally forgive any such loans to Baidu Netcom given that Baidu Netcom provides sufficient proof for its loss and incapacity to repay. The agreement will terminate when the shareholders of Baidu Netcom have transferred all their equity interests in Baidu Netcom to Baidu Online or its designated person.

Each of the exclusive equity purchase option agreements amongst Baidu Online and Beijing Perusal, BaiduPay and Baidu HR and their respective shareholders contains the same terms as those described above. Each of the agreements will terminate upon the shareholders of Beijing Perusal, BaiduPay or Baidu HR have transferred all their equity interests in Beijing Perusal, BaiduPay or Baidu HR, as the case may be, to Baidu Online or its designated person.

Proxy Agreement/Power of Attorney Agreement

Pursuant to the proxy agreement between Baidu Online and the shareholders of Baidu Netcom, the shareholders of Baidu Netcom agreed to entrust all the rights to exercise their voting power to the person(s) designated by Baidu Online. The shareholders of Baidu Netcom have each executed an irrevocable power of attorney to appoint the person(s) designated by Baidu Online as their attorney-in-fact to vote on their behalf on all matters requiring shareholder approval. The proxy agreement would be in effect for an unlimited term unless terminated in writing by Baidu Online earlier. The power of attorney would be in effect for as long as the shareholders of Baidu Netcom hold any equity interests in Baidu Netcom.

Each of the proxy agreements amongst Baidu Online and the shareholders of Beijing Perusal, BaiduPay, and Baidu HR contain the same terms as those described above. Each of the proxy agreements will be in effect for an unlimited term unless terminated in writing by Baidu Online. Each of the powers of attorney will be in effect for as long as the shareholder of Beijing Perusal, BaiduPay or Baidu HR holds any equity interests in Beijing Perusal, BaiduPay or Baidu HR, as the case may be.

Operating Agreement

Pursuant to the operating agreement amongst Baidu Online, Baidu Netcom and the shareholders of Baidu Netcom, Baidu Online provides guidance and instructions on Baidu Netcom’s daily operations and financial affairs. Baidu Online has the right to appoint senior executives of Baidu Netcom. The shareholders of Baidu Netcom must appoint the candidates recommended by Baidu Online as their representatives on Baidu Netcom’s board of directors. In addition, Baidu Online agrees to guarantee Baidu Netcom’s performance under any agreements or arrangements relating to Baidu Netcom’s business arrangements with any third party. Baidu Netcom, in return, agrees to pledge its accounts receivable and all of its assets to Baidu Online. Moreover, Baidu Netcom agrees that without the prior consent of Baidu Online, Baidu Netcom will not engage in any transactions that could materially affect the assets, liabilities, rights or operations of Baidu Netcom, including, without limitation, incurrence or assumption of any indebtedness, sale or purchase of any assets or rights, incurrence of any encumbrance on any of its assets or intellectual property rights in favor of a third party or transfer of any agreements relating to its business operation to any third party. The agreement will be in effect for an unlimited term, until the term of business of one party expires and is denied extension by the relevant approval authorities.

Each of the operating agreements amongst Baidu Online and Beijing Perusal, BaiduPay, and Baidu HR and their respective shareholders contains the same terms as those described above. Each of the agreements will be in effect for an unlimited term, until the term of business of one party expires and is denied extension by the relevant approval authorities.

Exclusive Technology Consulting and Services Agreement

Pursuant to the exclusive technology consulting and services agreement between Baidu Online and Baidu Netcom, Baidu Online has the exclusive right to provide to Baidu Netcom technology consulting and services related to, among other things, the maintenance of servers, software development, design of advertisements, and e-commerce technical services. Baidu Online also seconds employees to Baidu Netcom for whom Baidu Netcom bears the costs and expenses. Baidu Online owns the intellectual property rights resulting from the performance of this agreement. Baidu Netcom pays a monthly service fee to Baidu Online based upon a pre-agreed formula as defined in the agreement. Baidu Online has the right to adjust the service fees at its sole discretion without the consent of Baidu Netcom. The agreement will be in effect for an unlimited term, until the term of business of one party expires and is denied extension by the relevant approval authorities.

Each of the exclusive technology consulting and services agreements between Baidu Online and Beijing Perusal, BaiduPay, and Baidu HR contains the same terms as those described above, except for the formula calculating the service fees. Baidu Netcom and Beijing Perusal should pay Baidu Online a monthly service fee equal to the product of the standard monthly fee for page view per thousand times multiplied by the actual times of page view for the month divided by 1,000, respectively; Baidu HR should pay its entire net income as technology consulting and service fee to Baidu Online; and the agreement between Baidu Online and BaiduPay does not provide a formula to calculate the quarterly fee, as BaiduPay has yet to achieve profitability. Each of the agreements will be in effect for an unlimited term, until the term of business of one party expires and is denied extension by the relevant approval authorities.

License Agreements

Baidu Online and Baidu Netcom entered into a software license agreement, a trademark license agreement, a domain name license agreement and a web layout copyright license agreement (collectively, the “License Agreements”). Pursuant to the License Agreements between Baidu Online and Baidu Netcom, Baidu Online has granted to Baidu Netcom the right to use (including but not limited to) a software license, a webpage copyright license, a trademark license, and a domain name license. Baidu Netcom may only use the licenses in their own business operations. Baidu Online has the right to adjust the service fees at its sole discretion. The original term of the software license agreement expired in March 2010 and was renewed on March 11, 2010. The renewed term will expire on March 10, 2015. The software license agreement may be extended by both parties in writing upon the expiration of this agreement. The original term of the trademark license agreement, domain name license agreement and web layout copyright license agreement expired on March 1, 2009 and was renewed then. The renewed term will expire on February 28, 2014.

Baidu Online entered into a trademark license agreement, domain name license agreement and web layout copyright license agreement with both Beijing Perusal and BaiduPay. Each of the license agreements between Baidu Online and Beijing Perusal, and Baidu Online and BaiduPay contains the same terms as those described above. The term of each agreement is 5 years from the execution date of the agreement on June 23, 2006 and February 28, 2008, respectively, and would be extended for one year automatically at its expiration unless Baidu Online provides written notice not to extend the agreements prior to their expiration.

Baidu Online and Baidu HR have not entered into any license agreements as of December 31, 2011. The license agreements with Beijing Perusal were extended automatically for one year and will expire on June 22, 2012.

Equity Pledge Agreement

Pursuant to the equity pledge agreement between the shareholders of Baidu Netcom and Baidu Online, the shareholders of Baidu Netcom pledged all of their equity interests in Baidu Netcom to Baidu Online to guarantee their obligations under the loan agreement and Baidu Netcom’s performance of its obligations under the exclusive technology consulting and service agreement. If Baidu Netcom or its shareholders breach their respective contractual obligations, Baidu Online, as the pledgee, will be entitled to certain rights, including the right to sell the pledged equity interests. The shareholders of Baidu Netcom agreed not to dispose of the pledged equity interests or take any actions that would prejudice Baidu Online’s interest. The equity pledge agreement will expire two years after expiration of the term or the fulfillment by Baidu Netcom and its shareholders of their respective obligations under the exclusive technology consulting and service agreement and the loan agreement.

Each of the equity pledge agreements amongst Baidu Online, Beijing Perusal, BaiduPay, and Baidu HR and the respective shareholders contains the same terms, including term period, as those described above. Each equity pledge is perfected by registration with relevant local administration for industry and commerce which is required for a property right under the PRC Property Rights Law.

Through the design of the aforementioned agreements, the shareholders of the VIEs effectively assigned their full voting rights to Baidu Online, which gives Baidu Online the power to direct the activities that most significantly impact the VIEs’ economic performance. Baidu Online obtains the ability to approve decisions made by the VIEs and the ability to acquire the equity interests in the VIEs when permitted by PRC law. Baidu Online is obligated to absorb a majority of the expected losses from the VIEs’ activities through providing unlimited financial support to the VIEs and is entitled to receive a majority of residual returns from the VIEs through the exclusive technology consulting and service fees. As a result of these contractual agreements, Baidu Online is determined to be the primary beneficiary of the VIEs. Despite the lack of technical majority ownership, there exists a parent-subsidiary relationship between the Company and VIEs through these contractual agreements, and the Company consolidates the VIEs through Baidu Online.

There are similar agreements entered into by Primary Beneficiaries other than Baidu Online with their VIEs and the respective shareholders, which results in a parent-subsidiary relationship between the Company and VIEs through these contractual agreements. The assets, liabilities and results of operations of these VIEs are insignificant.

The management believes that, (i) the ownership structure of the Company and its VIEs is in compliance with existing PRC laws and regulations; (ii) the contractual arrangements with the VIEs and their shareholders are valid and binding, and will not result in any violation of PRC laws or regulations currently in effect; and (iii) the Group’s business operations are in compliance with existing PRC laws and regulations in all material respects.

However, uncertainties in the PRC legal system could cause the Company’s current ownership structure to be found in violation of existing and/or future PRC laws or regulations and could limit the Company’s ability, through the Primary Beneficiaries, to enforce its rights under these contractual arrangements. Furthermore, shareholders of the VIEs may have interests that are different than those of the Company, which could potentially increase the risk that they would seek to act contrary to the terms of the above aforementioned agreements.

In addition, if the current structure or any of the contractual arrangements were found to be in violation of any existing or future PRC law, the Company may be subject to penalties, which may include but not be limited to, the cancellation or revocation of the Company’s business and operating licenses, being required to restructure the Company’s operations or discontinue the Company’s operating activities. The imposition of any of these or other penalties may result in a material and adverse effect on the Company’s ability to conduct its operations. In such case, the Company may not be able to operate or control the VIEs, which may result in deconsolidation of the VIEs.

The following tables set forth the assets, liabilities and results of operations of the VIEs and their subsidiaries included in the Company’s consolidated balance sheets and statements of comprehensive income:


	As of December 31,
	2010		2011
	RMB		RMB		US$
	(In thousands)
Total assets		1,194,045		1,808,784		287,387
current		564,729		1,008,640		160,257
non-current		629,316		800,144		127,130

Total liabilities		852,945		1,456,328		231,387
current		766,945		1,342,268		213,265
non-current		86,000		114,060		18,122


	For the years ended December 31,
	2009		2010		2011
	RMB		RMB		RMB		US$
	(In thousands)
Total revenues		934,814		1,832,629		4,205,327		668,159
Net income		27,263		46,234		119,294		18,954

As of December 31, 2011, there was no pledge or collateralization of their assets. The amount of the net assets of VIEs, which are restricted under PRC laws and regulations (Note 15), was RMB352.46 million (US$56.00 million) as of December 31, 2011.

Basis of Accounting

The consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”).

Principles of Consolidation

The consolidated financial statements include the financial statements of the Company, its subsidiaries and VIEs. All inter-company transactions and balances between the Company, its subsidiaries and VIEs are eliminated upon consolidation. The Company has included the results of operations of acquired businesses from the respective dates of acquisition.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the period. Management evaluates estimates, including those related to the accounts receivable allowances, fair values of options to purchase the Company’s or its subsidiaries’ ordinary shares, fair values of certain equity investments, the purchase price allocation and fair value of noncontrolling interests with respect to the business combinations, and deferred tax valuation allowance, among others. Management bases the estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results could differ from these estimates.

Comparative Information

The items of intangible assets and accounts payable and accrued liabilities in prior years’ consolidated financial statements have been reclassified to conform to the current year’s presentation to facilitate comparison as a result of increases of significance of those items.

Currency Translation for Financial Statements Presentation

Translations of amounts from RMB into US$ for the convenience of the reader have been calculated at the exchange rate of RMB6.2939 per US$1.00 on December 30, 2011, the last business day in fiscal year 2011, as published on the website of the United States Federal Reserve Board. No representation is made that the RMB amounts could have been, or could be, converted into U.S. dollars at such rate.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (Class A Ordinary Shares)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Class A Ordinary Shares
Number of American depositary shares ("ADSs") representing one Class A ordinary share	10	10	10

ORGANIZATION, CONSOLIDATION AND PRESENTATION OF FINANCIAL STATEMENTS - Additional Information (Detail) In Millions, unless otherwise specified			12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2011 Baidu Netcom CNY	Dec. 31, 2011 Beijing Perusal CNY	Dec. 31, 2011 Beijing Perusal License Agreements Excluding Software License Agreement	Dec. 31, 2011 BaiduPay CNY	Dec. 31, 2011 BaiduPay License Agreements Excluding Software License Agreement	Dec. 31, 2011 Baidu HR CNY
Variable Interest Entity [Line Items]
Interest-free loans provided by a subsidiary of the entity to the shareholders of its variable interest entities			100	1		9		50
Agreements, automatic extension period					1 year		1 year
Term of License Agreements excluding software license agreement					5 years		5 years
Equity pledge agreement expiration period			2 years	2 years		2 years		2 years
Net assets of VIEs (in which the Company has no legal ownership)	$ 56.00	352.46
Exchange rate used for conversion of financial statements from RMB to US dollar	6.2939	6.2939

Estimated Useful lives Of Fixed Assets (Detail)	12 Months Ended
Estimated Useful lives Of Fixed Assets (Detail)	Dec. 31, 2011 Year
Office building
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	45
Office building related facility, machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	15
Computer equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	3
Property, plant and equipment, useful life, maximum (in years)	5
Internal use software development costs
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	3
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	3
Property, plant and equipment, useful life, maximum (in years)	5
Vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, minimum (in years)	5
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	Over the shorter of lease terms or estimated useful lives of the assets

Weighted Average Useful lives From Date of Purchase of Intangible Assets (Detail)	12 Months Ended
	Dec. 31, 2011 Year
Land use right
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset weighted average useful life (in years)	50
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset weighted average useful life (in years)	9.3
Software
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset weighted average useful life (in years)	4.8
Trademarks
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset weighted average useful life (in years)	10
User List
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset weighted average useful life (in years)	3.0
Others
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset weighted average useful life (in years)	4.2

BUSINESS COMBINATION - Additional Information (Detail)	1 Months Ended		12 Months Ended				1 Months Ended
BUSINESS COMBINATION - Additional Information (Detail)	Jul. 20, 2011 Qunar USD ($)	Jul. 20, 2011 Qunar CNY	Dec. 31, 2011 Qunar USD ($)	Dec. 31, 2011 Qunar CNY	Jul. 20, 2011 Qunar Redeemable Noncontrolling Interest	Jul. 20, 2011 Qunar Noncontrolling Interest	Jul. 20, 2011 Qunar Trademarks USD ($) Year	Jul. 20, 2011 Qunar Trademarks CNY Year	Jul. 20, 2011 Qunar Customer relationships USD ($) Year	Jul. 20, 2011 Qunar Customer relationships CNY Year	Jul. 20, 2011 Qunar Software USD ($) Year	Jul. 20, 2011 Qunar Software CNY Year	Jul. 20, 2011 Qunar User List USD ($) Year	Jul. 20, 2011 Qunar User List CNY Year	Dec. 31, 2011 Other Acquirees USD ($)	Dec. 31, 2011 Other Acquirees CNY
Business Acquisition [Line Items]
Business combination, percentage of equity interests acquired	62.01%	62.01%
Business combination, purchase consideration	$ 300,280,000	1,939,569,000
Business combination, cash paid upon acquisition	260,100,000
Business combination, amount deposited in an escrow account	40,180,000
Business combination, escrow period	18 months	18 months
Business combination, fair value assigned to acquired finite-lived intangible assets by major class							50,460,000	317,600,000	35,220,000	221,700,000	2,260,000	14,200,000	25,110,000	158,070,000
Business combination, estimated useful life assigned to acquired finite-lived intangible assets by major class							10	10	10	10	5	5	3	3
Business combination, acquisition related costs			1,210,000	7,580,000
Business combination, amount of revenue of the acquiree included in the Company's consolidated statements of comprehensive income from the acquisition date			23,370,000	147,080,000
Business combination, amount of net income of the acquiree included in the Company's consolidated statements of comprehensive income from the acquisition date			420,000	2,640,000
Percentage of equity interest held by the noncontrolling shareholders of the acquiree or the majority-owned subsidiary					34.25%	3.74%
Business combination, redemption price per share for redeemable noncontrolling interests of the acquiree	$ 1.4553
Business combination, goodwill	356,635,000	2,294,266,000													27,740,000	174,610,000
Business combination, intangible assets	113,057,000	711,570,000													5,090,000	32,040,000
Business combination, liabilities assumed															$ 5,990,000	37,720,000

Summary of Estimated Fair Values of Assets Acquired, Liabilities Assumed and Noncontrolling Interest - Qunar (Detail) (Qunar) In Thousands, unless otherwise specified	Jul. 20, 2011 USD ($)	Jul. 20, 2011 CNY
Business Acquisition [Line Items]
Purchase consideration	$ 300,280	1,939,569
Cash and cash equivalents	13,312	83,784
Short-term investments	6,182	38,907
Accounts receivables	3,542	22,292
Other current assets	3,923	24,694
Property, plant and equipment, net	2,283	14,367
Intangible assets, net	113,057	711,570
Accounts payable and accrued liabilities	(10,888)	(68,529)
Deferred tax liabilities, noncurrent	(21,744)	(136,856)
Noncontrolling interests	(16,353)	(102,922)
Redeemable noncontrolling interests	(149,669)	(942,004)
Goodwill	$ 356,635	2,294,266

Short-Term Investments (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 Fixed-rate Investments USD ($)	Dec. 31, 2011 Fixed-rate Investments CNY	Dec. 31, 2010 Fixed-rate Investments CNY	Dec. 31, 2011 Adjustable-rate Investments USD ($)	Dec. 31, 2011 Adjustable-rate Investments CNY
Gain (Loss) on Investments [Line Items]
Held-to-maturity securities, amortized cost		9,848,848	376,492		100,048
Held-to-maturity securities, gross unrecognized holding gains		10,504	5		0
Held-to-maturity securities, gross unrecognized holding losses		(25,077)	(1,263)		(21)
Held-to-maturity securities, fair value	1,562,509	9,834,275	375,234	15,893	100,027
Available-for-sale securities, amortized cost					102,637
Available-for-sale securities, gross unrealized gains					45
Available-for-sale securities, fair value				$ 16,314	102,682

INVESTMENTS - Long-term investments (Cost method investments) - Additional Information (Detail) In Millions, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY	Dec. 31, 2011 Cost Method Investee ANJUKE Inc USD ($)	Dec. 31, 2011 Cost Method Investee ANJUKE Inc CNY
Schedule of Investments [Line Items]
Carrying amount of cost method investments	$ 61.91	389.63	204.35
Cash consideration for a cost method investment				$ 23.00	144.76

Accounts Receivable (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 96,182	605,364	299,123
Allowance for doubtful accounts	(922)	(5,806)	(2,223)
Accounts receivable, net	$ 95,260	599,558	296,900

Other Assets Current (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Deposits	$ 2,834	17,837	22,832
Advances to suppliers	3,885	24,452	14,913
Prepaid expenses	5,059	31,838	33,275
Interest receivable	2,831	17,818	5,994
Receivables from employees	1,180	7,425	25,014
Receivables from service providers	812	5,114	682
Receivables from financial institutions	31,855	200,494	0
Other	1,594	10,034	944
Other assets, current	$ 50,050	315,012	103,654

Fixed Assets (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY	Dec. 31, 2011 Computer equipment USD ($)	Dec. 31, 2011 Computer equipment CNY	Dec. 31, 2010 Computer equipment CNY	Dec. 31, 2011 Office building USD ($)	Dec. 31, 2011 Office building CNY	Dec. 31, 2010 Office building CNY	Dec. 31, 2011 Office building related facility, machinery and equipment USD ($)	Dec. 31, 2011 Office building related facility, machinery and equipment CNY	Dec. 31, 2010 Office building related facility, machinery and equipment CNY	Dec. 31, 2011 Internal use software development costs USD ($)	Dec. 31, 2011 Internal use software development costs CNY	Dec. 31, 2010 Internal use software development costs CNY	Dec. 31, 2011 Vehicles USD ($)	Dec. 31, 2011 Vehicles CNY	Dec. 31, 2010 Vehicles CNY	Dec. 31, 2011 Office equipment USD ($)	Dec. 31, 2011 Office equipment CNY	Dec. 31, 2010 Office equipment CNY	Dec. 31, 2011 Leasehold improvements USD ($)	Dec. 31, 2011 Leasehold improvements CNY	Dec. 31, 2010 Leasehold improvements CNY
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross				$ 548,175	3,450,160	1,956,642	$ 62,579	393,865	391,895	$ 21,800	137,209	137,542	$ 13,992	88,065	37,022	$ 1,103	6,943	6,829	$ 28,203	177,509	82,431	$ 28,430	178,932	74,793
Property, plant and equipment, gross excluding construction in progress	704,282	4,432,683	2,687,154
Accumulated depreciation	(268,740)	(1,691,424)	(1,079,539)
Construction in progress	474	2,982	14,797
Fixed assets, net	$ 436,016	2,744,241	1,622,412

Finite-Lived Intangible Assets (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY	Dec. 31, 2011 Land use right USD ($)	Dec. 31, 2011 Land use right CNY	Dec. 31, 2010 Land use right CNY	Dec. 31, 2011 Customer relationships USD ($)	Dec. 31, 2011 Customer relationships CNY	Dec. 31, 2010 Customer relationships CNY	Dec. 31, 2011 Software USD ($)	Dec. 31, 2011 Software CNY	Dec. 31, 2010 Software CNY	Dec. 31, 2011 Trademarks USD ($)	Dec. 31, 2011 Trademarks CNY	Dec. 31, 2010 Trademarks CNY	Dec. 31, 2011 Others USD ($)	Dec. 31, 2011 Others CNY	Dec. 31, 2010 Others CNY	Dec. 31, 2011 User List USD ($)	Dec. 31, 2011 User List CNY
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying value		1,037,608	159,190		223,309	97,611		254,169	31,408		44,350	12,131		320,527	1,727		37,183	16,313		158,070
Finite-lived intangible assets, accumulated amortization		(115,967)	(53,802)		(11,252)	(6,995)		(40,168)	(26,870)		(7,465)	(3,572)		(14,567)	(248)		(19,097)	(16,117)		(23,418)
Finite-lived intangible assets, impairment loss		(5,540)			0			(1,031)			(3,424)			0			(1,085)			0
Finite-lived intangible assets, net carrying value	$ 145,554	916,101	105,388	$ 33,692	212,057	90,616	$ 33,838	212,970	4,538	$ 5,316	33,461	8,559	$ 48,612	305,960	1,479	$ 2,702	17,001	196	$ 21,394	134,652

Estimated Amortization Expense Relating To Existing Intangible Assets with Finite Lives (Detail) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY
Estimated amortization expense
2012	$ 20,170	126,945
2013	19,780	124,493
2014	15,468	97,352
2015	10,240	64,452
2016	$ 9,924	62,463

Indefinite-Lived Intangible Assets (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY	Dec. 31, 2011 Domain names USD ($)	Dec. 31, 2011 Domain names CNY	Dec. 31, 2010 Domain names CNY	Dec. 31, 2011 Trademarks USD ($)	Dec. 31, 2011 Trademarks CNY	Dec. 31, 2010 Trademarks CNY	Dec. 31, 2011 License USD ($)	Dec. 31, 2011 License CNY	Dec. 31, 2010 License CNY
Indefinite-lived intangible assets				$ 1,487	9,360	9,360	$ 564	3,550	1,050	$ 318	2,000	0
Indefinite-lived intangible assets, gross	2,369	14,910	10,410
Impairment loss	(397)	(2,500)	0
Indefinite-lived intangible assets	$ 1,972	12,410	10,410

Accounts Payable and Accrued Liabilities (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY
Accounts Payable and Accrued Liabilities [Line Items]
Accrued payroll and welfare	$ 41,512	261,273	150,160
Accrued operating expenses	86,937	547,176	297,248
Tax payable	71,886	452,441	295,432
Distributors' and customers' deposits	9,785	61,589	14,953
Purchase of fixed assets	43,968	276,731	277,669
Traffic acquisition costs	33,204	208,980	133,864
Bandwidth costs	12,244	77,061	34,488
Professional expenses	6,324	39,803	25,937
Deposits on online payment platform	5,889	37,067	38,278
Payable for business acquisitions	69,828	439,488	1,000
Others	22,853	143,836	48,742
Accounts payable and accrued liabilities	$ 404,430	2,545,445	1,317,771

LOANS PAYABLE - Short-Term Loan - Additional Information (Detail) (Baidu Holdings, Secured Debt) In Millions, unless otherwise specified	1 Months Ended
	Jan. 11, 2011 USD ($)	Jan. 11, 2011 CNY	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY
Debt Instrument [Line Items]
Specific amount up to which borrowings can be made under the commitment of a bank loan	$ 30.00	188.82
The percentage points added to LIBOR to compute the floating interest rate per annum	1.50%	1.50%
Period within which a specific amount can be borrowed under the commitment of a bank loan (in months or years)	12 months	12 months
Amount borrowed under the commitment of a bank loan			$ 20.00	125.88

LOANS PAYABLE - Long-Term Loans Payable - Additional Information (Detail) (Unsecured Debt) In Millions, unless otherwise specified	1 Months Ended				1 Months Ended
	Oct. 27, 2010 Baidu Netcom USD ($)	Oct. 27, 2010 Baidu Netcom CNY	Dec. 31, 2011 Baidu Netcom USD ($)	Dec. 31, 2011 Baidu Netcom CNY	Jul. 19, 2011 Baidu, Inc. USD ($)	Jul. 19, 2011 Baidu, Inc. CNY
Debt Instrument [Line Items]
Unsecured loan, maturity period (in years)					2 years	2 years
Unsecured loan borrowed from Goldman Sachs Lending Partners LLC					$ 350.00	2,202.87
Annual interest rate	5.60%	5.60%			1.30%	1.30%
Specific amount up to which borrowings can be made under the commitment of a bank loan	22.24	140.00
Amount borrowed under the commitment of a bank loan			22.24	140.00
Period within which a specific amount can be borrowed under the commitment of a bank loan (in months or years)	3 years	3 years
Amount of long-term loan due within one year				46.0

Long-Term Loans Payable (Detail) In Thousands, unless otherwise specified			12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2011 Loans Payable, Due July 30, 2012 USD ($)	Dec. 31, 2011 Loans Payable, Due July 30, 2012 CNY	Dec. 31, 2011 Loans Payable, Due October 30, 2012 USD ($)	Dec. 31, 2011 Loans Payable, Due October 30, 2012 CNY	Dec. 31, 2011 Loans Payable, Due January 30, 2013 USD ($)	Dec. 31, 2011 Loans Payable, Due January 30, 2013 CNY	Dec. 31, 2011 Loans Payable, Due April 30, 2013 USD ($)	Dec. 31, 2011 Loans Payable, Due April 30, 2013 CNY	Dec. 31, 2011 Loans Payable, Due July 30, 2013 USD ($)	Dec. 31, 2011 Loans Payable, Due July 30, 2013 CNY	Dec. 31, 2011 Loans Payable, Due October 30, 2013 USD ($)	Dec. 31, 2011 Loans Payable, Due October 30, 2013 CNY
Long Term Debt Maturities Repayments Of Principal [Line Items]
Debt, maturity date			Jul. 30, 2012	Jul. 30, 2012	Oct. 30, 2012	Oct. 30, 2012	Jan. 30, 2013	Jan. 30, 2013	Apr. 30, 2013	Apr. 30, 2013	Jul. 30, 2013	Jul. 30, 2013	Oct. 30, 2013	Oct. 30, 2013
Long-term loans from bank ,principal amounts due at maturity dates	$ 22,244	140,000	$ 3,654	23,000	$ 3,654	23,000	$ 3,654	23,000	$ 3,654	23,000	$ 3,654	23,000	$ 3,974	25,000

INCOME TAXES - Additional Information (Detail)	12 Months Ended			12 Months Ended				48 Months Ended		24 Months Ended	36 Months Ended	12 Months Ended							3 Months Ended		12 Months Ended	24 Months Ended	12 Months Ended	36 Months Ended		12 Months Ended				24 Months Ended	36 Months Ended	3 Months Ended		24 Months Ended	12 Months Ended
INCOME TAXES - Additional Information (Detail)	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY	Dec. 31, 2011 Domestic Country	Dec. 31, 2011 Domestic Country Maximum	Dec. 31, 2011 Foreign Country	Dec. 31, 2011 Foreign Country Maximum	Dec. 31, 2011 Qualified HNTE After 2008	Dec. 31, 2011 Qualified HNTE Granted With Tax Holiday Before 2008 and Verified as Qualified HNTE After 2008	Dec. 31, 2007 Qualified Software Enterprise	Dec. 31, 2010 Qualified Software Enterprise	Dec. 31, 2007 Some Qualified Software Enterprise Before 2008	Dec. 31, 2011 Transitional EIT Rate	Dec. 31, 2010 Transitional EIT Rate	Dec. 31, 2009 Transitional EIT Rate	Dec. 31, 2008 Transitional EIT Rate	Dec. 31, 2012 Transitional EIT Rate Forecast	Dec. 31, 2012 Baidu, Inc. Forecast	Jun. 30, 2011 Baidu Online USD ($)	Jun. 30, 2011 Baidu Online CNY	Dec. 31, 2011 Baidu Online	Dec. 31, 2009 Baidu Online	Dec. 31, 2010 Baidu Online Key Software Enterprise	Dec. 31, 2011 Baidu Times	Dec. 31, 2008 Baidu Times	Dec. 31, 2011 Baidu China	Dec. 31, 2010 Baidu China	Dec. 31, 2009 Baidu China	Dec. 31, 2008 Baidu China	Dec. 31, 2007 Baidu China	Dec. 31, 2010 Baidu China	Jun. 30, 2011 Baidu Netcom USD ($)	Jun. 30, 2011 Baidu Netcom CNY	Dec. 31, 2011 Baidu Netcom	Dec. 31, 2012 Baidu Netcom Forecast	Dec. 31, 2011 Baidu HK	Dec. 31, 2011 Baidu Japan CNY	Dec. 31, 2011 Baidu Japan JPY (¥)
Income Taxes [Line Items]
Unified statutory income tax rate under current EIT law	25.00%	25.00%															25.00%	25.00%
A preferential enterprise income tax rate								15.00%	15.00%			15.00%									15.00%	15.00%	10.00%									15.00%	15.00%	15.00%	15.00%
Number of years of tax rate reduction subsequent to years of tax exemption											3 years													3 years							3 years
Number of years of tax exemption										2 years															3 years					2 years
Applicable statutory enterprise income tax rates from tax reduction on transitional tax rates																										24.00%	11.00%	10.00%	9.00%
Reduction rate on applicable enterprise income tax rates											50.00%													50.00%							50.00%
Transitional enterprise income tax rates													24.00%	22.00%	20.00%	18.00%										24.00%
Income tax deduction in connection with over-accrued (or over-paid) provisional tax																			$ 12,950,000	81,500,000												$ 3,480,000	21,930,000
Statutory withholding tax rate to which dividends paid by a FIE to any of its foreign non-resident enterprise investors are subject under current EIT law	10.00%	10.00%
Special withholding tax rate to which dividends paid by a FIE to any of its foreign non-resident enterprise investors are subject under current EIT law																																				5.00%
Minimum paid-in capital required for a specified Japan national income tax rate																																						100,000,000
A specified Japan national income tax rate																																					30.00%	30.00%
Valuation allowances on the related net deferred tax assets	40,503,000	254,919,000	179,959,000																																		226,450,000
Net Operating Loss Carryforwards	$ 116,640,000	734,100,000
Beginning expiration year of net operating loss				2017		2015
Time period that tax authorities could conduct examinations of entity's tax filings					5 years		7 years
Tax years remain open to examination by respective taxing jurisdictions				tax years 2007-2011		tax years 2007-2011

Tax Effects of Temporary Differences that Give Rise to Deferred Tax Balances (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Provision for doubtful receivables	$ 411	2,586	1,964
Fixed assets depreciation	5,763	36,274	41,089
Net operating loss carry-forward	39,529	248,790	173,644
Accrued expenses, payroll and others	22,372	140,805	80,592
Deferred tax assets	68,075	428,455	297,289
Valuation allowance	(40,503)	(254,919)	(179,959)
Deferred tax assets, net	27,572	173,536	117,330
Intangible assets arising from business combinations	20,914	131,629	0
Deferred tax liabilities	$ 20,914	131,629	0

Future Minimum Payments Under Non-Cancelable Operating Leases with Initial Terms of One-Year or More (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY
Operating Leased Assets [Line Items]
2012	$ 79,260	498,853
2013	60,327	379,692
2014	38,603	242,967
2015	29,122	183,288
2016	23,122	145,527
Thereafter	7,568	47,635
Operating Leases, Future Minimum Payments Due, Total	$ 238,002	1,497,962

Summary of Redeemable Noncontrolling Interest (Parenthetical) (Detail) (B.D. Mobile)	Dec. 31, 2011
B.D. Mobile
Redeemable Noncontrolling Interest [Line Items]
Percentage of equity interest of redeemable noncontrolling shareholders	6.98%

SHAREHOLDERS' EQUITY - Additional Information (Detail) In Billions, except Share data, unless otherwise specified	12 Months Ended								12 Months Ended		12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009	Aug. 31, 2005	Dec. 31, 2011 PRC USD ($)	Dec. 31, 2011 PRC CNY	Dec. 31, 2010 PRC CNY	Dec. 31, 2011 Preferred Shares USD ($)	Dec. 31, 2011 Class A Ordinary Shares USD ($)	Dec. 31, 2010 Class A Ordinary Shares USD ($)	Dec. 31, 2011 Class B Ordinary Shares USD ($)	Dec. 31, 2010 Class B Ordinary Shares USD ($)
Stockholders Equity Note [Line Items]
Issuance of Class B Ordinary shares upon conversion of all convertible preferred shares upon completion of IPO				16,648,877
Common stock, shares authorized	870,400,000	870,400,000						10,000,000	825,000,000	825,000,000	35,400,000	35,400,000
Par value per share (US$)	$ 0.00005	$ 0.00005						$ 0.00005	$ 0.00005	$ 0.00005	$ 0.00005	$ 0.00005
Number of votes per share									1		10
Transfer of Class B ordinary shares to Class A Ordinary shares	1,332	650,000	419,654
Common stock, shares outstanding									27,111,117	27,045,340	7,803,000	7,804,332
Minimum required percentage of each of the entity's PRC subsidiaries' after-tax profits to allocate to a general reserve fund	10.00%
Maximum requirement of each of the entity's PRC Subsidiaries' after-tax profits to be allocated to a general reserve fund as a percentage of each Subsidiaries' registered capital	50.00%
Minimum required percentage of each of the entity's PRC VIEs' after-tax profits to allocate to a statutory surplus fund	10.00%
Maximum requirement of each of the entity's PRC VIEs' after-tax profits to be allocated to a statutory surplus fund as a percentage of each VIEs' registered capital	50.00%
Minimum required percentage of each of the entity's PRC VIEs' after-tax profits to allocate to a statutory public welfare fund	5.00%
Maximum required percentage of each of the entity's PRC VIEs' after-tax profits to allocate to a statutory public welfare fund	10.00%
Amount of net assets of entity's PRC subsidiaries and VIEs restricted from being transferred to entity					$ 0.19	1.22	1.15

Shareholders' Equity (Detail) In Thousands, unless otherwise specified	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CNY	Dec. 31, 2010 CNY
Retained Earnings Adjustments [Line Items]
PRC statutory reserve funds	$ 39,702	249,880	238,107
Unreserved retained earnings	2,121,809	13,354,454	6,727,590
Retained earnings	$ 2,161,511	13,604,334	6,965,697

EARNINGS PER SHARE ("EPS") - Additional Information (Detail)	12 Months Ended	16 Months Ended	20 Months Ended
	Dec. 31, 2010	May 12, 2010	Dec. 31, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Previous Ratio of ADS-to-Class A Ordinary Share		one ADS for one share
Current Ratio of ADS-to-Class A Ordinary Share			ten ADSs for one share
The split whose effect is the same with the entity's change of the ADS to Class A ordinary share ratio	ten-for-one ADS split

SHARE-BASED AWARDS PLAN - Additional Information (Detail) In Millions, except Share data, unless otherwise specified	12 Months Ended					12 Months Ended		12 Months Ended													12 Months Ended				6 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 Baidu, Inc. Share Option Except ISO to More Than Ten Percent Voting Power Employee Under 2008 Plan Year	Dec. 31, 2011 Baidu, Inc. ISO to More Than Ten Percent Voting Power Employee Under 2008 Plan Year	Dec. 31, 2011 Baidu, Inc. ISO to More Than Ten Percent Voting Power Employee Under 2008 Plan Minimum	Dec. 31, 2011 Baidu, Inc. 2000 Plan	Dec. 31, 2011 Baidu, Inc. Share Option Under 2000 Plan	Dec. 31, 2011 Baidu, Inc. 2008 Plan	Dec. 31, 2011 Baidu, Inc. Restricted Stock USD ($) Year	Dec. 31, 2011 Baidu, Inc. Restricted Stock CNY	Dec. 31, 2010 Baidu, Inc. Restricted Stock CNY	Dec. 31, 2009 Baidu, Inc. Restricted Stock CNY	Dec. 31, 2011 Baidu, Inc. Restricted Stock Maximum	Dec. 31, 2011 Baidu, Inc. Restricted Stock Minimum	Dec. 31, 2011 Baidu, Inc. Stock Options USD ($) Year	Dec. 31, 2011 Baidu, Inc. Stock Options CNY	Dec. 31, 2010 Baidu, Inc. Stock Options USD ($)	Dec. 31, 2010 Baidu, Inc. Stock Options CNY	Dec. 31, 2009 Baidu, Inc. Stock Options USD ($)	Dec. 31, 2009 Baidu, Inc. Stock Options CNY	Dec. 31, 2011 Qunar 2007 Plan	Dec. 31, 2011 Qunar 2007 Plan Maximum Year	Dec. 31, 2011 Qunar 2007 Plan Minimum	Dec. 31, 2011 Qunar Stock Options USD ($) Year	Dec. 31, 2011 Qunar Stock Options CNY Year	Dec. 31, 2011 Qunar Stock Option USD ($)	Dec. 31, 2011 Qunar Stock Option CNY	Dec. 31, 2011 Qunar Stock Incentive Plan 2007 After Amended
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved ordinary shares for issuance under share-based awards plan					5,040,000		3,428,777													9,600,140							26,060,000
Percentage of share-based awards granted generally vest after the first year of service						25.00%
Remaining vesting period						36 months
Maximum contractual term of share-based awards granted		10	5																		10
Minimum percentage of voting power of the entity's share capital	10.00%
Percentage of the fair market value of the entity's ordinary shares				110.00%																		100.00%
Shares vesting term (in years)												4 years	2 years								4 years	2 years
Total intrinsic value of options exercised														$ 43.83	275.86		263.97		340.13
Unrecognized share-based compensation cost								52.18	328.42					8.43	53.09								6.02	37.91
A weighted-average vesting period over which the deferred cost is expected to be recognized (in years)								2.89	2.89					2.53	2.53								2.72	2.72
The weighted-average grant-date fair value of options granted during respective years														$ 432.68		$ 279.69		$ 94.10
Total fair value of shares vested during respective years, restricted shares								31.58	198.77	237.71	201.83
Total fair value of shares vested during respective years, options																									$ 0.79	5.02

Option Activity - Baidu, Inc. (Detail) (Baidu, Inc., USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Year
Baidu, Inc.
Options outstandng - Number of shares
Outstanding, December 31, 2010	99,175
Granted	12,748
Exercised	(37,330)
Forfeited/Cancelled	(2,594)
Expired	0
Outstanding, December 31, 2011	71,999
Vested and expected to vest at December 31, 2011	67,258
Exercisable at December 31, 2011	37,991
Options outstanding - weighted-average exercise price
Outstanding, December 31, 2010	$ 237.99
Granted	$ 1,218.68
Exercised	$ 105.57
Forfeited/Cancelled	$ 511.19
Expired	$ 0
Outstanding, December 31, 2011	$ 470.45
Vested and expected to vest at December 31, 2011	$ 460.47
Exercisable at December 31, 2011	$ 254.67
Options outstanding - weighted-average remaining contractual life (in years)
Outstanding, December 31, 2010	2.57
Outstanding, December 31, 2011	2.62
Vested and expected to vest at December 31, 2011	2.59
Exercisable at December 31, 2011	2.06
Options outstanding - aggregate intrinsic value (in thousands)
Outstanding, December 31, 2010	$ 72,164
Outstanding, December 31, 2011	51,539
Vested and expected to vest at December 31, 2011	48,782
Exercisable at December 31, 2011	$ 34,573

Assumptions Used to Estimate Fair Values of Share Options Granted - Baidu, Inc. (Detail) (Baidu, Inc.)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009 Year
Share based Compensation Arrangement Assumptions Used to Estimate Fair Values of Share Options Granted [Line Items]
Risk-free interest rate			1.18%
Dividend yield	0.00%	0.00%	0.00%
Expected volatility range			85.43%
Weighted average expected volatility	58.27%	68.12%	85.43%
Expected life (in years)			2.65
Minimum
Share based Compensation Arrangement Assumptions Used to Estimate Fair Values of Share Options Granted [Line Items]
Risk-free interest rate	0.31%	0.61%
Expected volatility range	48.20%	64.76%
Expected life (in years)	2.66	2.65
Maximum
Share based Compensation Arrangement Assumptions Used to Estimate Fair Values of Share Options Granted [Line Items]
Risk-free interest rate	1.03%	1.13%
Expected volatility range	61.58%	69.70%
Expected life (in years)	3.00	2.66

Restricted Shares Activity (Detail) (Baidu, Inc., USD $)	12 Months Ended
	Dec. 31, 2011
Baidu, Inc.
Number of Shares - Unvested
Unvested, December 31, 2010	49,617
Granted	40,558
Vested	(27,115)
Forfeited	(6,838)
Unvested, December 31, 2011	56,222
Weighted Average Grant Date Fair Value
Unvested, December 31, 2010	$ 643.22
Granted	$ 1,372.90
Vested	$ 535.64
Forfeited	$ 972.08
Unvested, December 31, 2011	$ 1,181.49

SEGMENT REPORTING - Additional Information (Detail)	Dec. 31, 2011
Segment Reporting Information [Line Items]
Number of operating segment	1