Parent Company Financial Statements - Statement of Condition (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Interest-bearing deposits with banks	$ 67,227	$ 70,935
Trading account assets	1,093	1,024
Investment securities available-for-sale	57,121	61,998
Other assets	31,018	38,328
Total assets	238,425	242,698
Liabilities:
Total liabilities	216,108	221,479
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Shareholders’ equity	22,317	21,219	$ 21,103	$ 21,328
Total liabilities and shareholders' equity	238,425	242,698
Parent Company
Assets:
Interest-bearing deposits with banks	532	3,635
Trading account assets	361	325
Investment securities available-for-sale	43	39
Consolidated banking subsidiary	23,080	22,147
Consolidated non-banking subsidiaries	6,762	2,687
Unconsolidated entities	63	297
Consolidated banking subsidiary	2,973	2,743
Consolidated non-banking subsidiaries and unconsolidated entities	143	126
Other assets	263	461
Total assets	34,220	32,460
Liabilities:
Accrued expenses and other liabilities	917	514
Long-term debt	10,986	10,727
Total liabilities	11,903	11,241
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Shareholders’ equity	22,317	21,219
Total liabilities and shareholders' equity	$ 34,220	$ 32,460