Fair Value Disclosures (Carrying Amounts and Fair Values of Financial Assets and Liabilities Not Recorded at Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
HTM securities, amortized cost	$ 13,751	$ 13,594
FDIC loss share receivable	299	479
Deposits	131,079	133,075
Long-term debt	19,362	19,114
Carrying Amount [Member]
HTM securities, amortized cost	13,751	13,594
Loans and leases,net of ALLL (excluding covered)	111,270	109,419
Covered loans, net of ALLL	2,623	3,166
FDIC loss share receivable	299	479
Deposits	131,079	133,075
Long-term debt	19,362	19,114
Estimate of Fair Value, Fair Value Disclosure [Member]
HTM securities, amortized cost	13,445	13,848
Loans and leases,net of ALLL (excluding covered)	111,207	109,621
Covered loans, net of ALLL	3,003	3,661
FDIC loss share receivable	(19)	149
Deposits	131,297	133,377
Long-term debt	20,314	20,676
Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
HTM securities, amortized cost	13,407	13,810
Loans and leases,net of ALLL (excluding covered)	0	0
Covered loans, net of ALLL	0	0
FDIC loss share receivable	0	0
Deposits	131,297	133,377
Long-term debt	20,314	20,676
Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
HTM securities, amortized cost	38	38
Loans and leases,net of ALLL (excluding covered)	111,207	109,621
Covered loans, net of ALLL	3,003	3,661
FDIC loss share receivable	(19)	149
Deposits	0	0
Long-term debt	$ 0	$ 0