Acquisitions, Goodwill, and Acquired Intangible Assets - Additional Informaiton (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Business Acquisition [Line Items]
Cash paid, net of cash acquired	$ 298
Indemnification holdback	43
Business Combination, Consideration Transferred	341
Goodwill	3,491		3,319
2015 Acquisitions
Business Acquisition [Line Items]
Goodwill	211
Intangible assets	154	[1]
Property and equipment	1
Deferred tax assets	27
Other assets acquired	20
Deferred tax liabilities	(53)
Other liabilities assumed	(19)
Business acquisition, allocation	341
Acquired intangible assets weighted-average amortization period	5 years
Contract-based | 2015 Acquisitions
Business Acquisition [Line Items]
Intangible assets	1	[1]
Technology-based | 2015 Acquisitions
Business Acquisition [Line Items]
Intangible assets	149	[1]
Customer-related | 2015 Acquisitions
Business Acquisition [Line Items]
Intangible assets	$ 4	[1]
Minimum | 2015 Acquisitions
Business Acquisition [Line Items]
Acquired intangible assets estimated useful lives	1 year
Maximum | 2015 Acquisitions
Business Acquisition [Line Items]
Acquired intangible assets estimated useful lives	6 years

[1] Acquired intangible assets have estimated useful lives of between one and six years, with a weighted-average amortization period of five years.