Income Taxes - Net Deferred Tax Balances (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Allowance for credit losses	$ 392	$ 283
Accrued expense, net	274	272
Unrealized losses on pension and postretirement benefits	401	389
Unrealized net losses on securities available for sale	101	97
Fair value adjustments for valuation of FDIC covered assets	125	159
Other	82	63
Total deferred tax assets	1,375	1,263
Deferred tax liabilities:
Leasing	779	759
Intangible assets	98	99
Pension liabilities	427	389
Other	0	5
Total deferred tax liabilities	1,304	1,252
Net deferred tax asset	$ 71	$ 11