No definition available.

Name:	us-gaap_CostOfRevenueAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the advertising revenues contract term.

+ References

No definition available.

+ Details

Name:	yy_AdvertisingRevenuesContractTerm
Namespace Prefix:	yy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period of estimated user relationship to recognize revenues.

+ References

No definition available.

+ Details

Name:	yy_EstimatedUserRelationshipPeriod
Namespace Prefix:	yy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period of initial course term.

+ References

No definition available.

+ Details

Name:	yy_InitialCourseTerm
Namespace Prefix:	yy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period over which amount billed to the third party advertising agencies and direct advertisers are due for payment.

+ References

No definition available.

+ Details

Name:	yy_PaymentsAccrualPeriod
Namespace Prefix:	yy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period of revenue-sharing contracts.

+ References

No definition available.

+ Details

Name:	yy_PeriodOfRevenueSharingContracts
Namespace Prefix:	yy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the tax rate of surcharges on business taxes and VAT.

+ References

No definition available.

+ Details

Name:	yy_SurchargesRateOnBusinessTaxAndValueAddedTax
Namespace Prefix:	yy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of tax rate on advertising service income subjected to cultural development fee.

+ References

No definition available.

+ Details

Name:	yy_TaxRateOnAdvertisingServiceIncome
Namespace Prefix:	yy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the rate at which value-added tax is levied on revenue of the entity.

+ References

No definition available.

+ Details

Name:	yy_ValueAddedTaxRate
Namespace Prefix:	yy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
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_ProductOrServiceAxis=yy_AdvertisingRevenuesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=yy_ThirdPartyDevelopedOnlineGamesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Principal accounting policies (Revenue Recognition and Cost of Revenues - Narrative) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue recognition [Line Items]
Initial course term	6 months
Cost of revenues
Tax rate on service income from provision of advertising services in the PRC (as a percent)	3.00%
Surcharges on business taxes and VAT (as a percent)	12.00%	12.00%	12.00%
Minimum [Member]
Cost of revenues
VAT (as a percent)	6.00%
Maximum [Member]
Cost of revenues
VAT (as a percent)	17.00%
Advertising revenues [Member] \| Minimum [Member]
Revenue recognition [Line Items]
Advertising revenues contract term	1 month
Advertising revenues [Member] \| Maximum [Member]
Revenue recognition [Line Items]
Advertising revenues contract term	3 months
Period over which payments are due	3 months
Third Party Developed Online Games [Member] \| Minimum [Member]
Revenue recognition [Line Items]
Period of revenue-sharing contracts	1 year
Estimated user relationship period	1 month
Third Party Developed Online Games [Member] \| Maximum [Member]
Revenue recognition [Line Items]
Period of revenue-sharing contracts	2 years
Estimated user relationship period	6 months