Income Taxes - Reconciliation of the Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]
Income tax expense at the federal statutory rate of 35%	$ 53	$ 84	$ 113
Foreign rate differential	(35)	(53)	(49)
State income taxes, net of effect of federal tax benefit	4	4	13
Unrecognized tax benefits and related interest	11	12	14
Change in cost-sharing treatment of stock-based compensation	(6)	(13)
Non-deductible transaction costs		1	1
Research tax credit	(10)	(3)	(2)
Stock-based compensation	2	2	2
Change in valuation allowance	9	5	5
Other, net	3	2	(1)
Provision for income taxes	$ 31	$ 41	$ 96