Name:	cmcm_DeferredGovernmentSubsidiaries
Namespace Prefix:	cmcm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The carrying amount of subsidiaries received or receivable from government as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP

No definition available.

Name:	cmcm_DeferredGovernmentSubsidiariesNonCurrent
Namespace Prefix:	cmcm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Definition

No definition available.

Name:	cmcm_DeferredRevenueCurrentAbstract
Namespace Prefix:	cmcm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The carrying amount of consideration received or receivable from customers as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer.

No definition available.

Name:	cmcm_DeferredRevenueFromCustomersCurrent
Namespace Prefix:	cmcm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The noncurrent portion of deferred revenue from customers amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

No definition available.

Name:	cmcm_DeferredRevenueFromCustomersNoncurrent
Namespace Prefix:	cmcm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Definition

No definition available.

Name:	cmcm_DeferredRevenueNoncurrentAbstract
Namespace Prefix:	cmcm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6935-107765

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 13.A.4(a).Q1)
-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 13
-Section A

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

The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.