SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Carrying Amounts and Classifications of Consolidated Assets (Details) $ in Millions	Jun. 30, 2015 USD ($) item	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2013 USD ($)
Variable Interest Entity
Cash	$ 23,413	$ 32,108	$ 35,268	$ 29,885
Trading account assets	279,197	296,786
Investments	332,121	333,443
Total loans, net	618,043	628,641
Other assets	135,929	122,122
Total assets	1,829,370	1,842,181
Consolidated VIEs
Variable Interest Entity
Cash	100	300
Trading account assets	1,100	700
Investments	6,600	8,000
Total loans, net	82,400	93,200
Other assets	6,100	600
Total assets	96,300	102,800
Short-term borrowings	15,300	22,700
Long-term debt	32,100	40,100
Other liabilities	5,300	900
Total Liabilities	52,700	63,700
Non-recourse liabilities	$ 50,300	61,200
With recourse liabilities, number of items | item	2
Consolidated VIEs | Letter of credit
Variable Interest Entity
Total Liabilities	$ 2,300	2,300
Consolidated VIEs | Credit guarantee
Variable Interest Entity
With recourse liabilities	83	198
Significant unconsolidated VIE assets
Variable Interest Entity
Trading account assets	5,900	7,600
Investments	2,600	2,600
Total loans, net	26,800	25,000
Other assets	2,000	2,000
Total assets	$ 37,300	$ 37,200