Income Taxes - Schedule of Temporary Tax Differences That Gave Rise to Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
ALLL	$ 359	$ 564
Postretirement plans	311	451
Net unrealized loss on AFS securities	112	155
Equity-based compensation	66	124
Reserves and expense accruals	114	238
Partnerships	70	116
Other	160	317
Total deferred tax assets	1,192	1,965
Deferred tax liabilities:
Prepaid pension plan expense	436	558
MSRs	234	358
Lease financing	366	587
Loan fees and expenses	114	103
Identifiable intangible assets	163	224
Other	31	45
Total deferred tax liabilities	1,344	1,875
Net deferred tax asset (liability)	$ (152)
Net deferred tax asset (liability)		$ 90