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	Sep. 30, 2014	Dec. 31, 2013
HTM securities	$ 20,717	$ 18,101
Deposits	130,895	127,475
Long-term debt	22,355	21,493
Carrying Amount [Member]
HTM securities	20,717	18,101
Loans and leases,net of ALLL (excluding covered)	115,839	112,264
Covered loans, net of ALLL	1,346	1,921
FDIC loss share receivable	609	843
Deposits	130,895	127,475
FDIC loss share payable	698	669
Long-term debt	22,355	21,493
Estimate of Fair Value, Fair Value Disclosure [Member]
HTM securities	20,502	17,530
Loans and leases,net of ALLL (excluding covered)	115,563	112,261
Covered loans, net of ALLL	1,561	2,200
FDIC loss share receivable	228	464
Deposits	131,107	127,810
FDIC loss share payable	689	652
Long-term debt	23,133	22,313
Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
HTM securities	20,502	17,491
Loans and leases,net of ALLL (excluding covered)	0	0
Covered loans, net of ALLL	0	0
FDIC loss share receivable	0	0
Deposits	131,107	127,810
FDIC loss share payable	0	0
Long-term debt	23,133	22,313
Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
HTM securities	0	39
Loans and leases,net of ALLL (excluding covered)	115,563	112,261
Covered loans, net of ALLL	1,561	2,200
FDIC loss share receivable	228	464
Deposits	0	0
FDIC loss share payable	689	652
Long-term debt	$ 0	$ 0