BUSINESS SEGMENTS - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of segments | segment			2
Revenues	$ 1,200	$ 1,473	$ 2,383	$ 2,639
Consumer Banking
Segment Reporting Information [Line Items]
Revenues	774	782	1,526	1,538
Consumer Banking | Maximum
Segment Reporting Information [Line Items]
Revenues			25
Commercial Banking
Segment Reporting Information [Line Items]
Revenues	$ 394	$ 371	770	$ 734
Commercial Banking | Minimum
Segment Reporting Information [Line Items]
Revenues			25
Commercial Banking | Maximum
Segment Reporting Information [Line Items]
Revenues			$ 2,500