Represents amount of assessable profits that are subject to taxation.

No definition available.

Name:	cmcm_AssessableProfits
Namespace Prefix:	cmcm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	cmcm_IncomeTaxesLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
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- Definition

Represents the tax exemption period for income tax rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	cmcm_
Data Type:	xbrli:durationItemType
Balance Type:	na
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- Definition

Represents the statutory corporate income tax rate in the foreign jurisdiction.

+ References

No definition available.

+ Details

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Namespace Prefix:	cmcm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the preferential tax rate applicable to the entity under the preferential tax treatment.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
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- Definition

Represents the percentage by which the tax rate is reduced for the three year period following the initial exemption period.

+ References

No definition available.

+ Details

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Namespace Prefix:	cmcm_
Data Type:	num:percentItemType
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- Definition

Represents the period during which the entity is entitled for a specified percentage reduction in income tax following the initial exemption period from the first profitable year.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
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- Definition

Represents amount of tax withheld.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the withholding income tax rate for dividend paid to foreign tax resident investors.

+ References

No definition available.

+ Details

Name:	cmcm_WithholdingIncomeTaxRateForDividendPaidToForeignTaxResidentInvestors
Namespace Prefix:	cmcm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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=6907707&loc=d3e32687-109319

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 6.I)

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-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319

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- Definition

Amount of current and deferred federal income tax expense (benefit) attributable to income (loss) from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32672-109319

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

-URI http://asc.fasb.org/extlink&oid=6515339

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h)(1))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Subparagraph 1

-Article 4

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Balance Type:	debit
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- Definition

The amount of income taxes from which a reporting entity is exempt or for which it will receive a reduction in income taxes as a result of the income tax holiday granted by the taxing jurisdiction.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SAB TOPIC 11.C)

-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330215-122817

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 11

-Section C

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- Definition

Per share amount effect of the income tax benefit resulting from the income tax holidays granted by taxing jurisdictions.

+ References

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INCOME TAXES (Details) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 CNY	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014 Cayman Island CNY	Dec. 31, 2014 British Virgin Island CNY	Dec. 31, 2014 UNITED STATES KS Mobile CNY	Dec. 31, 2013 UNITED STATES KS Mobile CNY	Dec. 31, 2014 HONG KONG Cheetah Technology	Dec. 31, 2014 HONG KONG HK Zoom	Dec. 31, 2014 HONG KONG Youloft HK	Dec. 31, 2014 CHINA	Dec. 31, 2014 CHINA New Software Development Enterprise USD ($)	Dec. 31, 2014 CHINA New Software Development Enterprise CNY	Dec. 31, 2013 CHINA New Software Development Enterprise CNY	Dec. 31, 2012 CHINA New Software Development Enterprise CNY	Dec. 31, 2014 CHINA Beijing Security New Software Development Enterprise	Dec. 31, 2013 CHINA Beijing Security New Software Development Enterprise	Dec. 31, 2012 CHINA Beijing Security New Software Development Enterprise	Dec. 31, 2014 CHINA Conew Network and Beike Internet New Software Development Enterprise Tax Year 2015 To 2017	Dec. 31, 2014 CHINA Zhuhai Juntian New Software Development Enterprise	Dec. 31, 2013 CHINA Zhuhai Juntian New Software Development Enterprise	Dec. 31, 2012 CHINA Zhuhai Juntian New Software Development Enterprise	Dec. 31, 2015 CHINA Zhuhai Juntian HNTE	Dec. 31, 2014 CHINA Zhuhai Juntian HNTE
Income taxes
Tax withheld	0cmcm_TaxWithheld			0	0
Foreign statutory tax rate						35.00%	35.00%	16.50%	16.50%	16.50%
Provision for federal income tax						0	0
Assessable profits						0	0
Statutory rate	25.00%	25.00%	25.00%								25.00%								12.50%
Exemption period for income tax												2 years	2 years
Period for reduction in tax percentage												3 years	3 years
Reduction in tax rate for three years following the exemption period (as a percent)												50.00%	50.00%
Preferential tax rate (as a percent)																12.50%	12.50%	12.50%		12.50%	12.50%	12.50%	15.00%	15.00%
Income Tax Holiday, Aggregate Dollar Amount												$ 6,529	40,509	4,430	4,201
Income tax holiday, income tax benefits per share												$ 0.0051	0.0314	0.0041	0.0042
Withholding income tax rate for dividend paid to foreign tax resident investors (as a percent)											10.00%