GOODWILL AND INTANGIBLE ASSETS - Components of Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	$ 13,823	$ 14,107
Accumulated amortization of Intangible assets (excluding MSRs)	10,330	10,386
Net carrying amount of Intangible assets (excluding MSRs)	3,493	3,721
Gross carrying amount, Mortgage servicing rights (MSRs)	1,524	1,781
Mortgage servicing rights (MSRs)	1,524	1,781
Gross carrying amount of Intangible assets	15,347	15,888
Accumulated amortization of Intangible assets	10,330	10,386
Net carrying amount of Intangible assets, balance at end of period	5,017	5,502
Indefinite-lived intangible assets
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	228	234
Accumulated amortization of Intangible assets (excluding MSRs)	0	0
Net carrying amount of Intangible assets (excluding MSRs)	228	234
Purchased credit card relationships
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	7,585	7,606
Accumulated amortization of Intangible assets (excluding MSRs)	6,542	6,520
Net carrying amount of Intangible assets (excluding MSRs)	1,043	1,086
Core deposit intangibles
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	984	1,050
Accumulated amortization of Intangible assets (excluding MSRs)	917	969
Net carrying amount of Intangible assets (excluding MSRs)	67	81
Other customer relationships
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	496	471
Accumulated amortization of Intangible assets (excluding MSRs)	268	252
Net carrying amount of Intangible assets (excluding MSRs)	228	219
Present value of future profits
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	37	37
Accumulated amortization of Intangible assets (excluding MSRs)	32	31
Net carrying amount of Intangible assets (excluding MSRs)	5	6
Other
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	4,493	4,709
Accumulated amortization of Intangible assets (excluding MSRs)	2,571	2,614
Net carrying amount of Intangible assets (excluding MSRs)	$ 1,922	$ 2,095