Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Loans And Leases Receivable [Line Items]
Current	$ 61,166,841	$ 63,854,815
30-89 Days past due	725,616	730,901
Purchased impaired	357,337	447,114
Nonaccrual	915,871	1,013,176
Total	63,659,042	66,570,957
Commercial, Financial, Leasing, etc. [Member]
Loans And Leases Receivable [Line Items]
Current	17,678,290	17,511,052
30-89 Days past due	91,757	62,479
Purchased impaired	16,257	17,437
Nonaccrual	111,116	151,908
Total	17,911,149	17,776,953
Commercial [Member]
Loans And Leases Receivable [Line Items]
Current	21,447,385	21,759,997
30-89 Days past due	179,972	118,249
Purchased impaired	101,049	132,962
Nonaccrual	198,397	193,859
Total	21,990,515	22,273,173
Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
Current	921,728	757,311
30-89 Days past due	10,622	35,419
Purchased impaired	138,651	187,764
Nonaccrual	113,096	181,865
Total	1,196,502	1,189,526
Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
Current	3,029,504	2,379,953
30-89 Days past due	16,903	35,274
Purchased impaired	68,539	68,971
Nonaccrual	36,326	36,812
Total	3,158,250	2,531,091
Residential [Member]
Loans And Leases Receivable [Line Items]
Current	7,884,094	9,811,956
30-89 Days past due	301,564	337,969
Purchased impaired	30,201	36,769
Nonaccrual	252,987	249,314
Total	8,830,995	10,794,316
Residential Alt-A [Member]
Loans And Leases Receivable [Line Items]
Current	297,840	331,021
30-89 Days past due	18,263	19,692
Purchased impaired
Nonaccrual	80,905	95,808
Total	397,008	446,521
Home Equity Lines and Loans [Member]
Loans And Leases Receivable [Line Items]
Current	6,027,315	6,199,591
30-89 Days past due	32,428	40,759
Purchased impaired	2,640	3,211
Nonaccrual	77,537	58,071
Total	6,169,392	6,321,950
Automobile [Member]
Loans And Leases Receivable [Line Items]
Current	1,144,216	2,442,502
30-89 Days past due	39,221	40,461
Purchased impaired
Nonaccrual	22,087	25,107
Total	1,205,705	2,508,321
Other [Member]
Loans And Leases Receivable [Line Items]
Current	2,736,469	2,661,432
30-89 Days past due	34,886	40,599
Purchased impaired
Nonaccrual	23,420	20,432
Total	2,799,526	2,729,106
Non-Acquired [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	339,792	358,397
Non-Acquired [Member] | Commercial, Financial, Leasing, etc. [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	2,582	23,490
Non-Acquired [Member] | Commercial [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	12,859	13,111
Non-Acquired [Member] | Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	52	3,258
Non-Acquired [Member] | Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	1,888	509
Non-Acquired [Member] | Residential [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	317,660	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	4,751	4,845
Acquired [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	153,585	166,554
Acquired [Member] | Commercial, Financial, Leasing, etc. [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	11,147	10,587
Acquired [Member] | Commercial [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	50,853	54,995
Acquired [Member] | Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	12,353	23,909
Acquired [Member] | Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	5,090	9,572
Acquired [Member] | Residential [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	44,489	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	29,472	20,318
Acquired [Member] | Automobile [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing	181	251
Acquired [Member] | Other [Member]
Loans And Leases Receivable [Line Items]
90 Days or more past due and accruing		$ 1,798