Asset Quality (Details 5) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	$ 49,575	$ 50,107
Commercial, financial and agricultural [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	19,378	16,441
RE-Commercial [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	8,037	9,502
RE-Construction [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	1,312	2,106
Commercial Lease [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	6,055	6,471
Commercial Loan [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	34,782	34,520
AAA-AA [Member] | Commercial, financial and agricultural [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	121	99
AAA-AA [Member] | RE-Commercial [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	3	2
AAA-AA [Member] | RE-Construction [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	3	0
AAA-AA [Member] | Commercial Lease [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	650	658
AAA-AA [Member] | Commercial Loan [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	777	759
A [Member] | Commercial, financial and agricultural [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	885	704
A [Member] | RE-Commercial [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	61	85
A [Member] | RE-Construction [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	3	4
A [Member] | Commercial Lease [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	1,159	1,245
A [Member] | Commercial Loan [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	2,108	2,038
BBB-BB [Member] | Commercial, financial and agricultural [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	16,347	12,386
BBB-BB [Member] | RE-Commercial [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	6,061	6,125
BBB-BB [Member] | RE-Construction [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	784	829
BBB-BB [Member] | Commercial Lease [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	3,812	3,796
BBB-BB [Member] | Commercial Loan [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	27,004	23,136
B [Member] | Commercial, financial and agricultural [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	803	1,282
B [Member] | RE-Commercial [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	622	1,349
B [Member] | RE-Construction [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	185	383
B [Member] | Commercial Lease [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	252	395
B [Member] | Commercial Loan [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	1,862	3,409
CCC-C [Member] | Commercial, financial and agricultural [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	1,222	1,970
CCC-C [Member] | RE-Commercial [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	1,290	1,941
CCC-C [Member] | RE-Construction [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	337	890
CCC-C [Member] | Commercial Lease [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	182	377
CCC-C [Member] | Commercial Loan [Member]
Commercial Credit Exposure Credit Risk Profile by Creditworthiness Category
Total Loans	$ 3,031	$ 5,178