SECURITIES - Income Recognized from Investment Securities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Interest Income, Securities, Operating, by Taxable Status [Abstract]
Taxable	$ 155	$ 154	$ 314	$ 303
Non-taxable	0	0	0	0
Total interest income from investment securities	155	154	314	303
Gain (Loss) on Sale of Investments [Abstract]
Gains on sale of debt securities	10	0	22	25
Losses on sale of debt securities	(1)	0	(5)	0
Debt securities gains, net	9	0	17	25
Equity securities gains	$ 1	$ 0	$ 3	$ 0