Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Performance by Loan Class) (Detail) - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		$ 15,513,650	$ 14,409,398	$ 13,749,996
Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		15,437,096	14,330,721	13,661,346
Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		76,554	78,677	88,650
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		4,330,344	3,924,394	3,640,430
Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		4,324,950	3,914,763	3,633,919
Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		5,394	9,631	6,511
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		4,850,590	4,505,753	4,353,472
Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		4,826,706	4,479,148	4,316,842
Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		23,884	26,605	36,630
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		712,350	716,293	713,642
Home equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		706,655	710,119	707,838
Home equity | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		5,695	6,174	5,804
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		503,015	483,542	451,905
Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		119,468	151,012	160,373
Consumer and other | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		119,078	150,617	159,184
Consumer and other | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		390	395	1,189
Commercial and industrial | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,534,459	2,233,364	2,012,480
Commercial and industrial | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,530,035	2,223,758	2,006,264
Commercial and industrial | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		4,424	9,606	6,216
Franchise | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		228,599	233,316	223,456
Franchise | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		227,694	233,316	223,456
Franchise | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		905	0	0
Mortgage warehouse lines of credit | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		213,797	139,003	148,211
Mortgage warehouse lines of credit | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		213,797	139,003	148,211
Mortgage warehouse lines of credit | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		0	0	0
Community Advanatage - homeowners association | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		114,883	106,364	94,009
Community Advanatage - homeowners association | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		114,883	106,364	94,009
Community Advanatage - homeowners association | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		0	0	0
Aircraft | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		6,831	8,065	7,847
Aircraft | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		6,831	8,065	7,847
Aircraft | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		0	0	0
Asset-based lending | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		832,455	806,402	778,344
Asset-based lending | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		832,455	806,377	778,049
Asset-based lending | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		0	25	295
Tax exempt | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		199,185	217,487	208,913
Tax exempt | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		199,185	217,487	208,913
Tax exempt | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		0	0	0
Leases | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		187,630	160,136	144,435
Leases | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		187,565	160,136	144,435
Leases | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		65	0	0
Other | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,772	11,034	9,792
Other | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,772	11,034	9,792
Other | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		0	0	0
PCI - commercial | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[1],[2]	9,733	9,223	12,943
PCI - commercial | Commercial | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[2]	9,733	9,223	12,943
PCI - commercial | Commercial | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[2]	0	0	0
Residential construction | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		57,602	38,696	29,959
Residential construction | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		57,602	38,696	29,959
Residential construction | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		0	0	0
Commercial construction | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		249,543	187,766	155,059
Commercial construction | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		249,524	187,536	154,220
Commercial construction | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		19	230	839
Land | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		87,837	91,830	105,927
Land | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		85,802	89,174	103,560
Land | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,035	2,656	2,367
Office | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		754,817	705,432	667,917
Office | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		747,756	698,144	656,967
Office | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		7,061	7,288	10,950
Industrial | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		627,407	623,970	617,640
Industrial | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		624,839	621,578	612,543
Industrial | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,568	2,392	5,097
Retail | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		749,991	731,488	697,095
Retail | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		747,639	727,336	690,186
Retail | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,352	4,152	6,909
Multi-family | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		668,448	605,742	636,169
Multi-family | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		666,718	605,493	635,480
Multi-family | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		1,730	249	689
Mixed use and other | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		1,592,122	1,465,117	1,378,439
Mixed use and other | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		1,584,003	1,455,479	1,368,660
Mixed use and other | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		8,119	9,638	9,779
PCI - commercial real estate | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[1],[2]	62,823	55,712	65,267
PCI - commercial real estate | Commercial real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[2]	62,823	55,712	65,267
PCI - commercial real estate | Commercial real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[2]	0	0	0
Residential real estate | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		500,673	481,308	449,123
Residential real estate | Residential real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		484,042	465,806	433,829
Residential real estate | Residential real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		16,631	15,502	15,294
PCI - residential real estate | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[1],[2]	2,342	2,234	2,782
PCI - residential real estate | Residential real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[2]	2,342	2,234	2,782
PCI - residential real estate | Residential real estate | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[2]	0	0	0
Commercial insurance loans | Premium finance receivables
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,460,408	2,350,833	2,378,529
Commercial insurance loans | Premium finance receivables | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,436,199	2,330,463	2,355,956
Commercial insurance loans | Premium finance receivables | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		24,209	20,370	22,573
Life insurance loans | Premium finance receivables
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,153,155	1,884,092	1,641,885
Life insurance loans | Premium finance receivables | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		2,152,804	1,884,092	1,641,236
Life insurance loans | Premium finance receivables | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans		351	0	649
PCI - life insurance loans | Premium finance receivables
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[1],[2]	384,320	393,479	409,760
PCI - life insurance loans | Premium finance receivables | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[2]	384,320	393,479	409,760
PCI - life insurance loans | Premium finance receivables | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	[2]	$ 0	$ 0	$ 0

[1] PCI loans represent loans acquired with evidence of credit quality deterioration since origination, in accordance with ASC 310-30. Loan agings are based upon contractually required payments.

[2] PCI loans represent loans acquired with evidence of credit quality deterioration since origination, in accordance with ASC 310-30. See Note 6 - Loans for further discussion of these purchased loans.