MORTGAGE BANKING - Changes Related to MSRs (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Valuation allowance for servicing assets:
Balance at end of period	$ 15	$ 28
Residential Mortgages
Servicing Asset at Amortized Cost, Balance [Roll Forward]
January 1	174	185	208	215
Amount capitalized	13	39
Amortization	(32)	(41)
Carrying amount before valuation allowance	189	213
Valuation allowance for servicing assets:
January 1	23	70
Valuation recovery	(8)	(42)
Balance at end of period	15	28
Net carrying value of MSRs	$ 174	$ 185	$ 208	$ 215