INCOME TAXES - Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Other comprehensive income	$ 271	$ 409
Allowance for credit losses	310	471
State net operating loss carryforwards	88	75
Accrued expenses not currently deductible	40	129
Investment and other tax credit carryforwards	65	52
Deferred income	0	22
Fair value adjustments	27	40
Other	0	6
Total deferred tax assets	801	1,204
Valuation allowance	(105)	(107)
Deferred tax assets, net of valuation allowance	696	1,097
Deferred tax liabilities:
Leasing transactions	525	881
Amortization of intangibles	352	522
Depreciation	182	234
Pension and other employee compensation plans	110	103
Partnerships	37	22
Deferred Income	27	0
MSRs	34	49
Total deferred tax liabilities	1,267	1,811
Net deferred tax liability	$ 571	$ 714