Equity Level 4 Capital Purchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding		4.4	7.2
Payments for Repurchase of Warrants		$ 0		$ 33
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 9.264	$ 9.388	$ 9.504
Warrant [Member]
Class of Stock [Line Items]
Warrants Exercised	18.1	2.8	25.2
Stock Repurchased During Period, Shares				1.6
Additional Paid-in Capital [Member]
Class of Stock [Line Items]
Payments for Repurchase of Warrants		$ 0	$ 0	$ 33