STOCKHOLDERS' EQUITY (Details) - USD ($)				12 Months Ended
	Aug. 03, 2015	Apr. 07, 2015	Apr. 06, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Preferred Stock
Preferred stock, authorized (in shares)				100,000,000	100,000,000
Preferred stock, outstanding (in shares)				250,000	250,000
Preferred stock, par value (in dollars per share)				$ 25.00	$ 25.00
Preferred stock, redemption notice period				90 days
Treasury Stock
Cost of stock repurchase		$ 250,000,000		$ 430,000,000	$ 500,000,000	$ 334,000,000
Treasury stock purchased (in shares)	9,615,384	10,473,397		17,300,000	20,100,000
Treasury stock purchased, price per share (in dollars per share)	$ 26.00	$ 23.87
Treasury stock purchased				$ 430,000,000	$ 500,000,000	334,000,000
Preferred stock, period used in determination of repurchase price		5 days
Deferred compensation, share-based payments
Treasury Stock
Cost of stock repurchase					$ 22,000,000
Treasury stock purchased, price per share (in dollars per share)					$ 25.50
Shares repurchased (in shares)				0	876,087
4.350% fixed rate subordinated debt, due 2025 | Subordinated Debt
Treasury Stock
Aggregate principal amount of debt	$ 250,000,000
Interest rate	4.35%
2016 CCAR Plan
Treasury Stock
Cost of stock repurchase				$ 430,000,000
Treasury stock purchased (in shares)				17,332,684
Treasury stock purchased, price per share (in dollars per share)				$ 24.81
Series A Preferred Stock
Preferred Stock
Preferred stock, authorized (in shares)				250,000	250,000
Preferred stock, par value (in dollars per share)			$ 25.00	$ 25.00	$ 25.00
Preferred stock, issued			$ 250,000,000
Preferred stock, issued (in shares)			250,000	250,000	250,000
Preferred stock, dividend rate			5.50%
Preferred stock, liquidation preference (in dollars per share)			$ 1,000	$ 1,000	$ 1,000
Net proceeds from issuance of stock			$ 247,000,000
Preferred stock, redemption price per share (in dollars per share)			$ 1,000
Series A Preferred Stock | LIBOR
Preferred Stock
Preferred stock, dividend payment rate, basis spread on variable rate, beginning after April 6, 2020			3.96%
Treasury Stock, at Cost
Treasury Stock
Treasury stock purchased				$ 405,000,000	$ 500,000,000	$ 334,000,000
Additional Paid-in Capital
Treasury Stock
Treasury stock purchased				$ 25,000,000