Loans and leases (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Summary of current, past due and nonaccrual loans
Current	$ 57,167,794	$ 49,757,337
30-89 days past due	725,654	654,559
Purchased impaired	653,362	97,019
Nonaccrual	1,097,581	1,139,740
Loans and leases, net of unearned discount	60,096,005	51,990,382
Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	163,738	91,022
Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	287,876	250,705
Commercial, financial, leasing, etc. [Member]
Summary of current, past due and nonaccrual loans
Current	15,493,803	13,091,963
30-89 days past due	37,112	97,692
Purchased impaired	23,762	2,250
Nonaccrual	163,598	173,365
Loans and leases, net of unearned discount	15,734,436	13,390,610
Commercial, financial, leasing, etc. [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	8,560	8,693
Commercial, financial, leasing, etc. [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	7,601	16,647
Commercial Real Estate Excluding Residential Builder and Developer and Other Construction [Member]
Summary of current, past due and nonaccrual loans
Current	19,658,761	16,594,914
30-89 days past due	172,641	92,866
Purchased impaired	192,804	8,275
Nonaccrual	171,111	184,361
Loans and leases, net of unearned discount	20,259,448	16,931,790
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	54,148	25,010
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	9,983	26,364
Residential builder and developer [Member]
Summary of current, past due and nonaccrual loans
Current	845,680	898,581
30-89 days past due	49,353	34,361
Purchased impaired	297,005	72,710
Nonaccrual	281,576	316,811
Loans and leases, net of unearned discount	1,508,333	1,351,490
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	21,116	28,204
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	13,603	823
Other commercial construction [Member]
Summary of current, past due and nonaccrual loans
Current	2,393,304	2,725,786
30-89 days past due	41,049	37,665
Purchased impaired	78,105	2,098
Nonaccrual	106,325	116,265
Loans and leases, net of unearned discount	2,643,333	2,899,881
Other commercial construction [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	23,582	7,718
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	968	10,349
Residential real estate excluding Alt-A [Member]
Summary of current, past due and nonaccrual loans
Current	6,626,182	4,699,711
30-89 days past due	256,017	229,641
Purchased impaired	56,741	9,320
Nonaccrual	172,681	162,001
Loans and leases, net of unearned discount	7,400,075	5,303,677
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	37,982	10,728
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	250,472	192,276
Residential Alt-A [Member]
Summary of current, past due and nonaccrual loans
Current	383,834	475,236
30-89 days past due	34,077	42,674
Purchased impaired	0	0
Nonaccrual	105,179	106,469
Loans and leases, net of unearned discount	523,090	624,379
Residential Alt-A [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	0	0
Residential Alt-A [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	0	0
Home equity lines and loans [Member]
Summary of current, past due and nonaccrual loans
Current	6,570,675	6,472,563
30-89 days past due	43,516	38,367
Purchased impaired	4,635	2,366
Nonaccrual	47,150	33,363
Loans and leases, net of unearned discount	6,681,385	6,556,351
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	15,409	9,692
Home equity lines and loans [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	0	0
Automobile [Member]
Summary of current, past due and nonaccrual loans
Current	2,644,330	2,608,230
30-89 days past due	48,342	44,604
Purchased impaired	0	0
Nonaccrual	26,835	31,866
Loans and leases, net of unearned discount	2,720,108	2,684,726
Automobile [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	601	26
Automobile [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	0	0
Other [Member]
Summary of current, past due and nonaccrual loans
Current	2,551,225	2,190,353
30-89 days past due	43,547	36,689
Purchased impaired	310	0
Nonaccrual	23,126	15,239
Loans and leases, net of unearned discount	2,625,797	2,247,478
Other [Member] | Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	2,340	951
Other [Member] | Non-Acquired Financing Receivable [Member]
Summary of current, past due and nonaccrual loans
90 days or more past due and accruing	$ 5,249	$ 4,246