Capital Stock (Details) - USD ($)		3 Months Ended		42 Months Ended
	Apr. 10, 2017	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Feb. 02, 2017
Class of Stock [Line Items]
Cash dividends paid		$ 25,000,000	$ 19,000,000
Cash dividends declared (dollars per share)		$ 0.10	$ 0.07
Payments for repurchase of stock		$ 25,000,000	$ 50,000,000
Common Stock
Class of Stock [Line Items]
Cash dividends paid		$ 25,000,000
Stock repurchase program, authorized amount					$ 2,100,000,000.0
Shares repurchased (in shares)		696,494		31,910,604
Average price of shares repurchased (dollars per share)		$ 35.89		$ 29.41
Payments for repurchase of stock		$ 25,000,000		$ 938,000,000
Subsequent Event | Common Stock
Class of Stock [Line Items]
Cash dividends declared (dollars per share)	$ 0.1
Cash dividends declared	$ 25,000,000
Payments for Share Repurchases Related to Employee Stock Based Compensation | Common Stock
Class of Stock [Line Items]
Shares repurchased (in shares)		0