Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Loans And Leases Receivable [Line Items]
Current	$ 63,487,050	$ 63,854,815
30-89 Days past due	629,060	730,901
Purchased impaired	394,697	447,114
Nonaccrual	964,906	1,013,176
Total	65,971,866	66,570,957
Commercial, Financial, Leasing, etc. [Member]
Loans And Leases Receivable [Line Items]
Current	17,803,206	17,511,052
30-89 Days past due	41,516	62,479
Purchased impaired	16,734	17,437
Nonaccrual	144,753	151,908
Total	18,021,812	17,776,953
Commercial [Member]
Loans And Leases Receivable [Line Items]
Current	21,646,755	21,759,997
30-89 Days past due	132,454	118,249
Purchased impaired	110,026	132,962
Nonaccrual	197,987	193,859
Total	22,145,535	22,273,173
Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
Current	796,756	757,311
30-89 Days past due	15,226	35,419
Purchased impaired	151,369	187,764
Nonaccrual	132,621	181,865
Total	1,110,606	1,189,526
Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
Current	2,709,159	2,379,953
30-89 Days past due	17,789	35,274
Purchased impaired	78,373	68,971
Nonaccrual	38,514	36,812
Total	2,860,253	2,531,091
Residential [Member]
Loans And Leases Receivable [Line Items]
Current	9,039,263	9,811,956
30-89 Days past due	298,767	337,969
Purchased impaired	35,534	36,769
Nonaccrual	254,033	249,314
Total	9,987,200	10,794,316
Residential Alt-A [Member]
Loans And Leases Receivable [Line Items]
Current	305,693	331,021
30-89 Days past due	21,464	19,692
Purchased impaired
Nonaccrual	85,392	95,808
Total	412,549	446,521
Home Equity Lines and Loans [Member]
Loans And Leases Receivable [Line Items]
Current	6,039,668	6,199,591
30-89 Days past due	33,205	40,759
Purchased impaired	2,661	3,211
Nonaccrual	70,488	58,071
Total	6,172,637	6,321,950
Automobile [Member]
Loans And Leases Receivable [Line Items]
Current	2,467,882	2,442,502
30-89 Days past due	32,752	40,461
Purchased impaired
Nonaccrual	20,533	25,107
Total	2,521,335	2,508,321
Other [Member]
Loans And Leases Receivable [Line Items]
Current	2,678,668	2,661,432
30-89 Days past due	35,887	40,599
Purchased impaired
Nonaccrual	20,585	20,432
Total	2,739,939	2,729,106
Non-Acquired [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	340,467	358,397
Non-Acquired [Member] | Commercial, Financial, Leasing, etc. [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	5,701	23,490
Non-Acquired [Member] | Commercial [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	14,397	13,111
Non-Acquired [Member] | Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	3,291	3,258
Non-Acquired [Member] | Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	79	509
Non-Acquired [Member] | Residential [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	312,703	313,184
Non-Acquired [Member] | Residential Alt-A [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing
Non-Acquired [Member] | Home Equity Lines and Loans [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing
Non-Acquired [Member] | Automobile [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing
Non-Acquired [Member] | Other [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	4,296	4,845
Acquired [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	155,686	166,554
Acquired [Member] | Commercial, Financial, Leasing, etc. [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	9,902	10,587
Acquired [Member] | Commercial [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	43,916	54,995
Acquired [Member] | Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	11,343	23,909
Acquired [Member] | Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	16,339	9,572
Acquired [Member] | Residential [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	46,900	45,124
Acquired [Member] | Residential Alt-A [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing
Acquired [Member] | Home Equity Lines and Loans [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	26,615	20,318
Acquired [Member] | Automobile [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	168	251
Acquired [Member] | Other [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	$ 503	$ 1,798