GOODWILL AND INTANGIBLE ASSETS - Changes in Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Finite and Indefinite-lived Intangible Assets
Net carrying amount at December 31, 2016, Intangible assets (excluding MSRs)	$ 5,114
Acquisitions/ divestitures	15
Amortization	(147)
FX translation and other	31
Net carrying amount at March 31, 2017, Intangible assets (excluding MSRs)	5,013	$ 5,114
Mortgage servicing rights (MSRs)	567	1,564
Total intangible assets	5,580	6,678
Indefinite-lived intangible assets
Finite and Indefinite-lived Intangible Assets
Net carrying amount at December 31, 2016, Intangible assets (excluding MSRs)	210
Acquisitions/ divestitures	0
Amortization	0
FX translation and other	17
Net carrying amount at March 31, 2017, Intangible assets (excluding MSRs)	227	210
Purchased credit card relationships
Finite and Indefinite-lived Intangible Assets
Net carrying amount at December 31, 2016, Intangible assets (excluding MSRs)	1,666
Acquisitions/ divestitures	20
Amortization	(33)
FX translation and other	1
Net carrying amount at March 31, 2017, Intangible assets (excluding MSRs)	1,654	1,666
Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Net carrying amount at December 31, 2016, Intangible assets (excluding MSRs)	2,972
Acquisitions/ divestitures	9
Amortization	(98)
FX translation and other	2
Net carrying amount at March 31, 2017, Intangible assets (excluding MSRs)	2,885	2,972
Core deposit intangibles
Finite and Indefinite-lived Intangible Assets
Net carrying amount at December 31, 2016, Intangible assets (excluding MSRs)	30
Acquisitions/ divestitures	0
Amortization	(6)
FX translation and other	2
Net carrying amount at March 31, 2017, Intangible assets (excluding MSRs)	26	30
Other customer relationships
Finite and Indefinite-lived Intangible Assets
Net carrying amount at December 31, 2016, Intangible assets (excluding MSRs)	202
Acquisitions/ divestitures	0
Amortization	(6)
FX translation and other	9
Net carrying amount at March 31, 2017, Intangible assets (excluding MSRs)	205	202
Present value of future profits
Finite and Indefinite-lived Intangible Assets
Net carrying amount at December 31, 2016, Intangible assets (excluding MSRs)	4
Acquisitions/ divestitures	0
Amortization	0
FX translation and other	1
Net carrying amount at March 31, 2017, Intangible assets (excluding MSRs)	5	4
Other
Finite and Indefinite-lived Intangible Assets
Net carrying amount at December 31, 2016, Intangible assets (excluding MSRs)	30
Acquisitions/ divestitures	(14)
Amortization	(4)
FX translation and other	(1)
Net carrying amount at March 31, 2017, Intangible assets (excluding MSRs)	$ 11	$ 30
American Airlines, Sears, The Home Depot, Costco and AT&T | Customer Concentration Risk | Intangible Assets, Excluding Mortgage Servicing Rights | Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Concentration risk, percentage	96.00%	97.00%