Summary of Fair Value of Assets Acquired and Liabilities Assumed in Conjunction with Acquisition (Parenthetical) (Detail) - Acquisitions During Period $ in Millions	6 Months Ended
	Jun. 30, 2015 USD ($)
Business Acquisition [Line Items]
Weighted average life of acquired intangible assets	5 years 8 months 12 days
Business acquisition, cash acquired	$ 41
Equity method investment, non-cash consideration	$ 99
Minimum
Business Acquisition [Line Items]
Estimated useful lives of acquired intangible assets	4 years
Maximum
Business Acquisition [Line Items]
Estimated useful lives of acquired intangible assets	10 years