Percentage of statutory corporate income tax rate applicable to pretax income (loss).

No definition available.

Name:	bidu_CorporateIncomeTaxRate
Namespace Prefix:	bidu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Income Tax Holiday Expiration Year

+ References

No definition available.

+ Details

Name:	bidu_IncomeTaxHolidayExpirationYear
Namespace Prefix:	bidu_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Income tax preferential period for entities entitled to the preferential tax treatment according to PRC government authorities.

+ References

No definition available.

+ Details

Name:	bidu_IncomeTaxPreferentialPeriod
Namespace Prefix:	bidu_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the preferential tax rate applicable to entities entitled to the preferential tax treatment according to PRC government authorities.

+ References

No definition available.

+ Details

Name:	bidu_IncomeTaxPreferentialTaxRate
Namespace Prefix:	bidu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Income Taxes [Line Items]

+ References

No definition available.

+ Details

Name:	bidu_IncomeTaxesLineItems
Namespace Prefix:	bidu_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Net Operating Loss Carryforward Period

+ References

No definition available.

+ Details

Name:	bidu_NetOperatingLossCarryforwardPeriod
Namespace Prefix:	bidu_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Net Operating Loss Carryforwards Begins To Expire

+ References

No definition available.

+ Details

Name:	bidu_NetOperatingLossCarryforwardsBeginsToExpire
Namespace Prefix:	bidu_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

The special withholding tax rate to which dividends paid by a foreign-invested enterprise onshore in China to any of its Hong Kong non-resident enterprise investors offshore are subject. These Hong Kong investors must meet the requirements stipulated by China's tax regulations.

+ References

No definition available.

+ Details

Name:	bidu_SpecialWithholdingTaxRateForDividend
Namespace Prefix:	bidu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Statutory Withholding Tax Rate For Capital Gains

+ References

No definition available.

+ Details

Name:	bidu_StatutoryWithholdingTaxRateForCapitalGains
Namespace Prefix:	bidu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The statutory withholding tax rate to which dividends paid by a foreign-invested enterprise onshore China to any of its foreign non-resident enterprise investors offshore are subject.

+ References

No definition available.

+ Details

Name:	bidu_StatutoryWithholdingTaxRateForDividend
Namespace Prefix:	bidu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum number of years after each fiscal year during which tax authorities could conduct examinations of an entity's tax filings.

+ References

No definition available.

+ Details

Name:	bidu_TimePeriodThatTaxAuthoritiesCouldConductExaminationsOfEntitysTaxFilings
Namespace Prefix:	bidu_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of deferred tax liability attributable to taxable temporary differences from undistributed earnings of subsidiaries and other recognized entities not within the country of domicile of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=96869850&loc=d3e28680-109314

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319

+ Details

Name:	us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I)
-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Tax year that remains open to examination under enacted tax laws, in CCYY format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

+ Details

Name:	us-gaap_OpenTaxYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

+ Details

Name:	us-gaap_OperatingLossCarryforwards
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of undistributed earnings of foreign subsidiaries intended to be permanently reinvested outside the country of domicile.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 740
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6487024&loc=d3e29054-158556

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 740
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6479915&loc=d3e66715-112838

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 995
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6503627&loc=d3e59836-110443

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96869850&loc=d3e28200-109314

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(c)
-URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

+ Details

Name:	us-gaap_UndistributedEarningsOfForeignSubsidiaries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	bidu_PreferentialTaxRateAxis=bidu_HighAndNewTechnologyEnterpriseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bidu_PreferentialTaxRateAxis=bidu_KeySoftwareEnterpriseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityNameAxis=us-gaap_StateAdministrationOfTaxationChinaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxPeriodAxis=us-gaap_EarliestTaxYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxPeriodAxis=us-gaap_LatestTaxYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityNameAxis=us-gaap_NationalTaxAgencyJapanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=bidu_BaiduHongKongMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=bidu_BaiduJapanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=bidu_BaiduOnlineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=bidu_BaiduChinaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=bidu_BaiduInternationalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=bidu_CertainPrcSubsidiariesAndViesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bidu_ExpirationDatesAxis=bidu_ExpirationPeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bidu_ExpirationDatesAxis=bidu_ExpirationPeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bidu_ExpirationDatesAxis=bidu_ExpirationPeriodThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Income Taxes - Additional Information (Detail) ¥ in Millions, $ in Millions	12 Months Ended				36 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2017 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2013 CNY (¥)
Income Taxes [Line Items]
Unified statutory income tax rate under current EIT law	25.00%
PRC statutory withholding tax rate to which dividends paid by a FIE to any of its foreign non-resident enterprise investors	10.00%
PRC special withholding tax rate to which dividends paid by a FIE to its foreign non-resident enterprise investors in Hong Kong	5.00%
Statutory withholding tax rate for capital gains	10.00%
Net losses deriving from entities in the PRC, Hong Kong and Japan	$ 1,200				$ 1,200	¥ 7,800
Accrued withholding tax	91	¥ 633			91	586	¥ 581
Undistributed earnings no withholding tax has accrued	$ 17,400				$ 17,400	¥ 113,100
High And New Technology Enterprise
Income Taxes [Line Items]
A preferential enterprise income tax rate	15.00%
Preferential enterprise income tax rate, effective period	3 years
Key Software Enterprise
Income Taxes [Line Items]
A preferential enterprise income tax rate	10.00%
PRC
Income Taxes [Line Items]
Net operating loss carryforward period	5 years
Net operating loss carryforwards begins to expire	2018
PRC \| Maximum
Income Taxes [Line Items]
Time period that tax authorities could conduct examinations of entity's tax filings	5 years
PRC \| Earliest Tax Year
Income Taxes [Line Items]
Tax years remain open to examination by respective taxing jurisdictions	2013
PRC \| Latest Tax Year
Income Taxes [Line Items]
Tax years remain open to examination by respective taxing jurisdictions	2017
Japan
Income Taxes [Line Items]
Net operating loss carryforward period	9 years
Net operating loss carryforwards begins to expire	2018
Baidu HK
Income Taxes [Line Items]
Income tax rate	16.50%
Baidu Japan
Income Taxes [Line Items]
Income tax rate	31.70%	33.50%	35.60%	38.00%
Baidu Online \| Key Software Enterprise
Income Taxes [Line Items]
A preferential enterprise income tax rate		10.00%	10.00%
Baidu China \| Key Software Enterprise
Income Taxes [Line Items]
A preferential enterprise income tax rate		10.00%	10.00%
Baidu International \| Key Software Enterprise
Income Taxes [Line Items]
A preferential enterprise income tax rate		10.00%
Certain PRC Subsidiaries and VIEs \| High And New Technology Enterprise
Income Taxes [Line Items]
A preferential enterprise income tax rate					15.00%
Certain PRC Subsidiaries and VIEs \| High And New Technology Enterprise \| Expiration Period One
Income Taxes [Line Items]
Tax holiday, expiration year	2018
Certain PRC Subsidiaries and VIEs \| High And New Technology Enterprise \| Expiration Period Two
Income Taxes [Line Items]
Tax holiday, expiration year	2019
Certain PRC Subsidiaries and VIEs \| High And New Technology Enterprise \| Expiration Period Three
Income Taxes [Line Items]
Tax holiday, expiration year	2020