SUBSEQUENT EVENTS - Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Apr. 22, 2015	Apr. 06, 2015	Apr. 07, 2015	Dec. 31, 2014
Subsequent Event [Line Items]
Preferred Stock, Par Value (in Dollars per Share)	$ 25					$ 25
Shares repurchased (in shares)	804,507
Cost of stock repurchase	$ 21
Shares repurchased, price per share (in dollars per share)	$ 25.38
Dividends paid (in dollars per share)	$ 0.10	$ 0.04
Dividends paid to common stockholders	16
Subsequent Event
Subsequent Event [Line Items]
Preferred Stock, Value, Subscriptions				250
Preferred Stock, Shares Issued				250,000
Preferred stock, dividend rate, percentage				5.50%
Preferred Stock, Par Value (in Dollars per Share)				$ 25.00
Preferred stock redemption price (in Dollars per Share)				$ 1,000
Dividends paid (in dollars per share)			$ 0.10
Dividends paid to common stockholders			55
Subsequent Event | RBSG
Subsequent Event [Line Items]
Shares repurchased (in shares)					10,473,397
Cost of stock repurchase					$ 250
Shares repurchased, price per share (in dollars per share)					$ 23.87
Ownership Percentage by RBS Group					40.80%
Subsequent Event | Noncumulative Preferred Stock | LIBOR
Subsequent Event [Line Items]
Preferred stock, dividend payment rate, basis spread on variable rate, beginning after April 6, 2020				3.96%