Parent Company Financial Statements (Parent Company Condensed Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets
Cash and due from banks	$ 1,639	$ 1,565
Interest-bearing deposits with banks	529	452
AFS securities, fair value	20,907	22,104
HTM securities	20,240	18,101
Other assets	13,090	14,512
Total assets	186,814	183,010
Liabilities and Shareholders' Equity
Short-term borrowings	3,717	4,138	2,864
Long-term debt	23,312	21,493
Accounts payable and other liabilities	6,319	7,095
Total liabilities	162,388	160,201
Total shareholders' equity	24,426	22,809	21,223	17,480
Total liabilities and shareholders' equity	186,814	183,010
Parent Company [Member]
Assets
Cash and due from banks	79	0
Interest-bearing deposits with banks	7,612	5,727
AFS securities, fair value	125	26
HTM securities	23	35
Investment in banking subsidiaries	22,711	22,314
Investment in other subsidiaries	1,452	1,281
Advances to / receivables from banking subsidiaries	63	106
Advances to / receivables from other subsidiaries	2,430	2,308
Other assets	168	194
Total assets	34,663	31,991
Liabilities and Shareholders' Equity
Short-term borrowings	0	24
Short-term borrowings due to subsidiaries	40	50
Long-term debt	10,081	9,032
Accounts payable and other liabilities	116	76
Total liabilities	10,237	9,182
Total shareholders' equity	24,426	22,809
Total liabilities and shareholders' equity	$ 34,663	$ 31,991