Loans and leases and the allowance for credit losses (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Summary of current, past due and nonaccrual loans
Current	$ 60,228,712	$ 57,167,794
30-89 days past due	656,447	725,654
Purchased impaired	560,700	653,362
Nonaccrual	968,328	1,097,581
Loans and leases, net of unearned discount	62,851,272	60,096,005
Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	274,598	287,876
Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	162,487	163,738
Commercial, financial, leasing [Member]
Summary of current, past due and nonaccrual loans
Current	16,138,169	15,493,803
30-89 days past due	73,581	37,112
Purchased impaired	16,424	23,762
Nonaccrual	153,556	163,598
Loans and leases, net of unearned discount	16,395,587	15,734,436
Commercial, financial, leasing [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	1,455	7,601
Commercial, financial, leasing [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	12,402	8,560
Commercial Real Estate Excluding Residential Builder and Developer and Other Construction [Member]
Summary of current, past due and nonaccrual loans
Current	20,854,618	19,658,761
30-89 days past due	128,489	172,641
Purchased impaired	164,855	192,804
Nonaccrual	173,278	171,111
Loans and leases, net of unearned discount	21,380,406	20,259,448
Commercial Real Estate Excluding Residential Builder and Developer and Other Construction [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	10,128	9,983
Commercial Real Estate Excluding Residential Builder and Developer and Other Construction [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	49,038	54,148
Residential builder and developer [Member]
Summary of current, past due and nonaccrual loans
Current	761,655	845,680
30-89 days past due	47,065	49,353
Purchased impaired	264,163	297,005
Nonaccrual	240,248	281,576
Loans and leases, net of unearned discount	1,333,674	1,508,333
Residential builder and developer [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	2,213	13,603
Residential builder and developer [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	18,330	21,116
Other commercial construction [Member]
Summary of current, past due and nonaccrual loans
Current	2,051,194	2,393,304
30-89 days past due	16,174	41,049
Purchased impaired	63,446	78,105
Nonaccrual	26,303	106,325
Loans and leases, net of unearned discount	2,184,627	2,643,333
Other commercial construction [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	4,352	968
Other commercial construction [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	23,158	23,582
Residential real estate excluding Alt-A [Member]
Summary of current, past due and nonaccrual loans
Current	8,563,870	6,626,182
30-89 days past due	252,076	256,017
Purchased impaired	47,135	56,741
Nonaccrual	174,937	172,681
Loans and leases, net of unearned discount	9,330,815	7,400,075
Residential real estate excluding Alt-A [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	251,750	250,472
Residential real estate excluding Alt-A [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	41,047	37,982
Residential Alt-A [Member]
Summary of current, past due and nonaccrual loans
Current	355,574	383,834
30-89 days past due	24,221	34,077
Nonaccrual	100,915	105,179
Loans and leases, net of unearned discount	480,710	523,090
Home equity lines and loans [Member]
Summary of current, past due and nonaccrual loans
Current	6,384,785	6,570,675
30-89 days past due	41,795	43,516
Purchased impaired	4,381	4,635
Nonaccrual	54,509	47,150
Loans and leases, net of unearned discount	6,500,733	6,681,385
Home equity lines and loans [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	15,263	15,409
Automobile [Member]
Summary of current, past due and nonaccrual loans
Current	2,490,590	2,644,330
30-89 days past due	34,961	48,342
Nonaccrual	24,482	26,835
Loans and leases, net of unearned discount	2,550,294	2,720,108
Automobile [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	261	601
Other [Member]
Summary of current, past due and nonaccrual loans
Current	2,628,257	2,551,225
30-89 days past due	38,085	43,547
Purchased impaired	296	310
Nonaccrual	20,100	23,126
Loans and leases, net of unearned discount	2,694,426	2,625,797
Other [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	4,700	5,249
Other [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	$ 2,988	$ 2,340