Computation of Basic and Diluted Earnings Per Class A and Class B Ordinary Share (Detail) ¥ / shares in Units, $ / shares in Units, ¥ in Millions, $ in Millions	12 Months Ended
Dec. 31, 2019 CNY (¥) ¥ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 CNY (¥) ¥ / shares shares	Dec. 31, 2017 CNY (¥) ¥ / shares shares
Numerator
Allocation of net income attributable to Baidu, Inc.	¥ 1,980	$ 285	¥ 27,443	¥ 18,318
Numerator
Numerator for diluted EPS calculation	1,952	281	27,443	18,318
Class A Ordinary Shares
Numerator
Allocation of net income attributable to Baidu, Inc.	¥ 1,571	$ 226	¥ 21,780	¥ 14,488
Denominator
Denominator used for basic EPS	27,633,243	27,633,243	27,697,335	27,464,760
Earnings per share - basic \| (per share)	¥ 56.84	$ 8.16	¥ 786.36	¥ 527.51
Numerator
Allocation of net income attributable to Baidu, Inc. for diluted computation	¥ 1,549	$ 223	¥ 21,824	¥ 14,513
Reallocation of net income attributable to Baidu, Inc. as a result of conversion of Class B to Class A shares	403	58	5,619	3,805
Numerator for diluted EPS calculation	¥ 1,952	$ 281	¥ 27,443	¥ 18,318
Denominator
Weighted average ordinary shares outstanding	27,633,243	27,633,243	27,697,335	27,464,760
Conversion of Class B to Class A ordinary shares	7,201,254	7,201,254	7,201,254	7,260,363
Share-based awards	50,357	50,357	272,454	227,268
Denominator used for diluted EPS	34,884,854	34,884,854	35,171,043	34,952,391
Earnings per share - diluted \| (per share)	¥ 55.96	$ 8.04	¥ 780.27	¥ 524.08
Class A Ordinary Shares \| American Depositary Shares
Denominator
Denominator used for basic EPS	276,332,430	276,332,430	276,973,350	274,647,600
Earnings per share - basic \| (per share)	¥ 5.68	$ 0.82	¥ 78.64	¥ 52.75
Denominator
Weighted average ordinary shares outstanding	276,332,430	276,332,430	276,973,350	274,647,600
Denominator used for diluted EPS	348,848,540	348,848,540	351,710,430	349,523,907
Earnings per share - diluted \| (per share)	¥ 5.60	$ 0.80	¥ 78.03	¥ 52.41
Class B Ordinary Shares
Numerator
Allocation of net income attributable to Baidu, Inc.	¥ 409	$ 59	¥ 5,663	¥ 3,830
Denominator
Denominator used for basic EPS	7,201,254	7,201,254	7,201,254	7,260,363
Earnings per share - basic \| (per share)	¥ 56.84	$ 8.16	¥ 786.36	¥ 527.51
Numerator
Allocation of net income attributable to Baidu, Inc. for diluted computation	¥ 403	$ 58	¥ 5,619	¥ 3,805
Numerator for diluted EPS calculation	¥ 403	$ 58	¥ 5,619	¥ 3,805
Denominator
Weighted average ordinary shares outstanding	7,201,254	7,201,254	7,201,254	7,260,363
Denominator used for diluted EPS	7,201,254	7,201,254	7,201,254	7,260,363
Earnings per share - diluted \| (per share)	¥ 55.96	$ 8.04	¥ 780.27	¥ 524.08

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Amount of increase (decrease) to net income used for calculating diluted earnings per share (EPS), resulting from the assumed exercise of dilutive convertible securities excluding adjustments related to ESOP convertible preferred stock, stock options, and restrictive stock units.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

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The earnings that is allocated to common stock and participating securities to the extent that each security may share in earnings as if all of the earnings for the period had been distributed.

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