VARIABLE INTEREST ENTITIES - Schedule of Affordable Housing Tax Credit Investments (Details) - LIHTC Investments - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Variable Interest Entity
Tax credits included in income tax expense	$ 25	$ 21
Amortization expense included in income tax expense	27	23
Other tax benefits included in income tax expense	$ 6	$ 7