Loans and Leases (Age Analysis of Past Due Financing Receivables) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivables That Are Accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	$ 42,950	$ 45,228
60-89 Days Past Due	19,569	13,488
Greater than 90 Days	8,451	10,077
Total Past Due	70,970	68,793
Current	12,486,189	10,222,659
Total Financing Receivables, Accruing	12,557,159	10,291,452
Financing Receivables That Are Accruing [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	6,334	7,843
60-89 Days Past Due	1,833	2,473
Greater than 90 Days	663	778
Total Past Due	8,830	11,094
Current	2,149,305	1,845,548
Total Financing Receivables, Accruing	2,158,135	1,856,642
Financing Receivables That Are Accruing [Member] | Real Estate - Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	954	342
60-89 Days Past Due	1,543	416
Greater than 90 Days	167	56
Total Past Due	2,664	814
Current	879,087	790,680
Total Financing Receivables, Accruing	881,751	791,494
Financing Receivables That Are Accruing [Member] | Real Estate Secured - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	11,202	21,330
60-89 Days Past Due	4,228	7,247
Greater than 90 Days	5,833	6,303
Total Past Due	21,263	34,880
Current	3,995,758	3,135,760
Total Financing Receivables, Accruing	4,017,021	3,170,640
Financing Receivables That Are Accruing [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	16,910	4,011
60-89 Days Past Due	9,314	1,043
Greater than 90 Days	696	884
Total Past Due	26,920	5,938
Current	3,868,138	3,069,452
Total Financing Receivables, Accruing	3,895,058	3,075,390
Financing Receivables That Are Accruing [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	5,732	7,688
60-89 Days Past Due	1,781	1,442
Greater than 90 Days	700	1,609
Total Past Due	8,213	10,739
Current	821,336	711,590
Total Financing Receivables, Accruing	829,549	722,329
Financing Receivables That Are Accruing [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,818	4,014
60-89 Days Past Due	870	867
Greater than 90 Days	392	447
Total Past Due	3,080	5,328
Current	772,565	669,629
Total Financing Receivables, Accruing	775,645	674,957
Financing Receivables That Are Accruing [Member] | Legacy Loans And Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	36,893	44,439
60-89 Days Past Due	17,558	12,325
Greater than 90 Days	7,478	9,732
Total Past Due	61,929	66,495
Current	10,226,189	9,617,812
Total Financing Receivables, Accruing	10,288,118	9,684,307
Financing Receivables That Are Accruing [Member] | Purchased Loans And Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	6,057	789
60-89 Days Past Due	2,011	1,163
Greater than 90 Days	973	345
Total Past Due	9,041	2,298
Current	2,260,000	604,847
Total Financing Receivables, Accruing	2,269,041	607,145
Financing Receivables That Are Nonaccruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	2,455	6,091
60-89 Days Past Due	7,146	10,773
Greater than 90 Days	79,163	93,647
Total Past Due	88,764	110,511
Current	29,684	45,967
Total Financing Receivables, Nonaccruing	118,448	156,478
Financing Receivables That Are Nonaccruing [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	86	454
60-89 Days Past Due	76	1,032
Greater than 90 Days	8,031	6,319
Total Past Due	8,193	7,805
Current	2,380	6,580
Total Financing Receivables, Nonaccruing	10,573	14,385
Financing Receivables That Are Nonaccruing [Member] | Real Estate - Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	159	122
60-89 Days Past Due	0	7,443
Greater than 90 Days	20,801	27,292
Total Past Due	20,960	34,857
Current	1,574	2,870
Total Financing Receivables, Nonaccruing	22,534	37,727
Financing Receivables That Are Nonaccruing [Member] | Real Estate Secured - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	756	2,569
60-89 Days Past Due	529	517
Greater than 90 Days	21,044	27,603
Total Past Due	22,329	30,689
Current	8,411	11,233
Total Financing Receivables, Nonaccruing	30,740	41,922
Financing Receivables That Are Nonaccruing [Member] | Real Estate Secured - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,454	2,946
60-89 Days Past Due	5,963	1,722
Greater than 90 Days	28,408	32,020
Total Past Due	35,825	36,688
Current	16,564	24,809
Total Financing Receivables, Nonaccruing	52,389	61,497
Financing Receivables That Are Nonaccruing [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
Greater than 90 Days	211	0
Total Past Due	211	0
Current	0	0
Total Financing Receivables, Nonaccruing	211	0
Financing Receivables That Are Nonaccruing [Member] | Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	0	0
60-89 Days Past Due	578	59
Greater than 90 Days	668	413
Total Past Due	1,246	472
Current	755	475
Total Financing Receivables, Nonaccruing	2,001	947
Financing Receivables That Are Nonaccruing [Member] | Legacy Loans And Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	2,117	6,091
60-89 Days Past Due	7,146	10,332
Greater than 90 Days	74,414	86,635
Total Past Due	83,677	103,059
Current	27,807	45,930
Total Financing Receivables, Nonaccruing	111,484	148,989
Financing Receivables That Are Nonaccruing [Member] | Purchased Loans And Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	338	0
60-89 Days Past Due	0	441
Greater than 90 Days	4,749	7,012
Total Past Due	5,087	7,452
Current	1,877	37
Total Financing Receivables, Nonaccruing	$ 6,964	$ 7,489