VARIABLE INTEREST ENTITIES - Schedule of Affordable Housing Tax Credit Investments (Details) - LIHTC Investments - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Variable Interest Entity
Tax credits included in income tax expense	$ 26	$ 22	$ 51	$ 43
Amortization expense included in income tax expense	28	22	55	45
Other tax benefits included in income tax expense	$ 6	$ 8	$ 12	$ 15