Capital Stock (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Oct. 06, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	May. 27, 2014	Apr. 01, 2014	Sep. 18, 2013
Class of Stock [Line Items]
Payments of Ordinary Dividends, Common Stock				$ 49	$ 43
Common Stock, Dividends, Per Share, Declared		$ 0.06	$ 0.06	$ 0.18	$ 0.16
Payments for Repurchase of Common Stock				$ 82	$ 97
Preferred Stock
Class of Stock [Line Items]
Convertible Preferred Stock, Aggregate Shares Issued upon Conversion							27,573,735
Convertible Preferred Stock, Shares Issued upon Conversion							2.7574
Common Stock
Class of Stock [Line Items]
Payments of Ordinary Dividends, Common Stock				$ 49
Stock Repurchase Program, Authorized Amount						$ 450		$ 100
Share Repurchase Program Expiration Date				Dec. 31, 2016
Treasury Stock, Shares, Acquired		1,001,309		2,601,438
Treasury Stock Acquired, Average Cost Per Share		$ 29.96		$ 30.75
Payments for Repurchase of Common Stock		$ 30		$ 80
Dividend Declared [Member] | Common Stock
Class of Stock [Line Items]
Dividends Payable, Date Declared	Oct. 06, 2015
Common Stock, Dividends, Per Share, Declared	$ 0.07
Dividends, Common Stock, Cash	$ 19
Dividends Payable, Date to be Paid	Dec. 01, 2015
Dividends Payable, Date of Record	Nov. 02, 2015
Payments for Share Repurchases Related to Employee Stock Based Compensation [Member] | Common Stock
Class of Stock [Line Items]
Treasury Stock, Shares, Acquired				75,520
Treasury Stock Acquired, Average Cost Per Share				$ 27.99
Payments for Repurchase of Common Stock				$ 2