Equity Level 4 (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended				9 Months Ended
	Oct. 26, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Class of Warrant or Right [Line Items]
Treasury stock acquired		8.4	7.8	8.4		24.6
Payments for Repurchase of Common Stock		$ 350	$ 350	$ 350		$ 1,050	$ 800
Accelerated Share Repurchases, Final Price Paid Per Share		$ 41,540,000	$ 44,740,000	$ 41,720,000
Warrants outstanding		4.1				4.1		4.4
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 9.161				$ 9.161		$ 9.264
Stock Repurchase Program, Authorized Amount		$ 1,300				$ 1,300
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased		280.0				280.0
Warrant [Member]
Class of Warrant or Right [Line Items]
Warrants Exercised		0.1			1.1	0.3	2.7
Treasury Stock [Member]
Class of Warrant or Right [Line Items]
Treasury Stock, Value, Acquired, Cost Method						$ 1,050	$ 800
Common Stock [Member]
Class of Warrant or Right [Line Items]
Treasury stock acquired						24,652.0	18,625.0
Subsequent Event [Member]
Class of Warrant or Right [Line Items]
Treasury Stock, Value, Acquired, Cost Method	$ 85
Treasury stock acquired	2.0