FAIR VALUE MEASUREMENT - Items Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Level 2
Items Measured at Fair Value on a Nonrecurring Basis
Loans held-for-sale	$ 713	$ 1,084
Other real estate owned	15	21
Loans	789	2,881
Total assets	1,517	3,986
Level 3
Items Measured at Fair Value on a Nonrecurring Basis
Loans held-for-sale	5,257	3,068
Other real estate owned	90	81
Loans	445	486
Total assets	5,792	3,635
Fair value
Items Measured at Fair Value on a Nonrecurring Basis
Loans held-for-sale	5,970	4,152
Other real estate owned	105	102
Loans	1,234	3,367
Total assets	$ 7,309	$ 7,621