Income Taxes - Net Deferred Tax Balances (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Allowance for credit losses	$ 443	$ 395
Accrued expense, net	384	274
Unrealized losses on pension and postretirement benefits	384	401
Unrealized net losses on securities available for sale	135	102
Fair value adjustments for valuation of FDIC covered assets	105	125
Other	52	142
Total deferred tax assets	1,503	1,439
Deferred tax liabilities:
Leasing	736	838
Intangible assets	79	98
Pension liabilities	479	427
Other	147	7
Total deferred tax liabilities	1,441	1,370
Net deferred tax asset	$ 62	$ 69