Income Taxes - Components of Current and Non-Current Deferred Income Tax Assets/(Liabilities) (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 179	$ 181
Interest expense limitation	654	734
Employee benefits	91	72
Tax credit carryforwards	130	142
Stock-based payments	32	41
Accrued expenses	57	39
Other assets	29	55
Total deferred tax assets, gross	1,172	1,264
Valuation allowances	(112)	(144)
Deferred tax assets, net of valuation allowances	1,060	1,120
Intangible assets	(1,591)	(1,640)
Fixed asset depreciation	(42)	(49)
Computer software	(301)	(280)
Deferred revenues/costs		(10)
Financial instruments	(14)	(6)
Unrealized gain on investments	(73)	(73)
Other liabilities	(87)	(58)
Total deferred income tax liabilities	(2,108)	(2,116)
Net deferred tax liability	$ (1,048)	$ (996)