INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
U.S. Federal income tax rate	35.00%	35.00%	35.00%
State operating loss carryforwards	$ 1,400,000,000
Deferred tax asset valuation allowance	105,000,000	$ 107,000,000
Decrease in deferred tax asset valuation allowance	2,000,000
Unrecognized tax benefits that would impact effective tax rate	5,000,000
Interest on unrecognized tax benefits accrued (released) during period	(8,000,000)	8,000,000	$ 1,000,000
Accrued interest on unrecognized tax benefits	1,000,000	22,000,000	14,000,000
Penalties accrued income tax examination	0	0	0
Penalties expense income tax examination	0	$ 0	$ 0
Revaluation of deferred tax liability - net tax benefit from 2017 Tax Legislation	331,000,000
Revaluation of deferred tax asset - net tax expense from 2017 Tax Legislation	145,000,000
Reclassification between AOCI and retained earnings for tax effects of 2017 Tax Legislation	145,000,000
Tax Years Ended Prior to 1988
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Base year loan loss reserves attributable to prior years	$ 557,000,000