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 (Schedule of Aging of the Company's Loan Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	$ 80,698		$ 77,710		$ 92,008
90+ days and still accruing	43,585		37,987		66,697
Current	14,917,238		14,408,516		13,144,491
Loans, net of unearned income, excluding covered loans	14,953,059		14,409,398		13,133,160
Nonaccrual	73,619		70,420		82,872
90+ days and still accruing	27,151		20,148		30,866
Current	14,737,743		14,213,075		12,890,704
Covered loans, Nonaccrual	7,079		7,290		9,136
Covered loans, 90 plus days and still accruing	16,434		17,839		35,831
Covered loans, Current	179,495		195,441		253,787
Covered loans	209,694		226,709		312,478
Total loans	15,162,753		14,636,107		13,445,638
60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	26,769		39,281		33,108
60-89 days past due	26,211		37,977		26,426
Covered loans, 60-89 days past due	558		1,304		6,682
30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	94,463		72,613		109,334
30-59 days past due	88,335		67,778		102,292
Covered loans, 30-59 days past due	6,128		4,835		7,042
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	5,586		9,157		11,782
90+ days and still accruing	612		839		1,466
Current	4,177,491		3,897,717		3,396,051
Loans, net of unearned income, excluding covered loans	4,211,932		3,924,394		3,439,197
Commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	5,112		5,123		2,235
Commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	23,131		11,558		27,663
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	5,586		9,132		11,112
90+ days and still accruing	0		474		387
Current	2,457,174		2,213,105		1,965,425
Loans, net of unearned income, excluding covered loans	2,484,465		2,233,364		1,995,309
Commercial | Commercial and industrial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,756		3,161		2,235
Commercial | Commercial and industrial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	16,949		7,492		16,150
Commercial | Franchise
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	225,305		231,789		221,026
Loans, net of unearned income, excluding covered loans	225,762		233,316		221,101
Commercial | Franchise | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		308		0
Commercial | Franchise | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	457		1,219		75
Commercial | Mortgage warehouse lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	186,372		139,003		60,809
Loans, net of unearned income, excluding covered loans	186,372		139,003		60,809
Commercial | Mortgage warehouse lines of credit | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial | Mortgage warehouse lines of credit | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial | Community Advanatage - homeowners association
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	108,382		106,364		91,414
Loans, net of unearned income, excluding covered loans	108,382		106,364		91,414
Commercial | Community Advanatage - homeowners association | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial | Community Advanatage - homeowners association | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial | Aircraft
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	6,295		8,065		8,840
Loans, net of unearned income, excluding covered loans	6,975		8,065		8,840
Commercial | Aircraft | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	291		0		0
Commercial | Aircraft | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	389		0		0
Commercial | Asset-based lending
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		25		670
90+ days and still accruing	0		0		0
Current	805,866		802,608		729,425
Loans, net of unearned income, excluding covered loans	810,685		806,402		740,668
Commercial | Asset-based lending | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		1,375		0
Commercial | Asset-based lending | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,819		2,394		10,573
Commercial | Tax exempt
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	205,195		217,487		177,973
Loans, net of unearned income, excluding covered loans	205,195		217,487		177,973
Commercial | Tax exempt | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial | Tax exempt | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial | Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	171,432		159,744		121,986
Loans, net of unearned income, excluding covered loans	172,014		160,136		121,986
Commercial | Leases | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	65		77		0
Commercial | Leases | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	517		315		0
Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	2,735		11,034		10,261
Loans, net of unearned income, excluding covered loans	2,735		11,034		10,261
Commercial | Other | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial | Other | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial | PCI - commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	[1]	0	[1]	0	[1]
90+ days and still accruing	612	[1]	365	[1]	1,079	[1]
Current	8,735	[1]	8,518	[1]	8,892	[1]
Loans, net of unearned income, excluding covered loans	9,347	[1],[2]	9,223	[1],[2]	10,836	[1],[2]
Commercial | PCI - commercial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	[1]	202	[1]	0	[1]
Commercial | PCI - commercial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	[1]	138	[1]	865	[1]
Commercial real-estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	29,982		26,605		33,733
90+ days and still accruing	18,120		10,976		21,073
Current	4,628,193		4,428,053		4,152,806
Loans, net of unearned income, excluding covered loans	4,710,486		4,505,753		4,262,255
Commercial real-estate | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	6,072		12,232		15,782
Commercial real-estate | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	28,119		27,887		38,861
Commercial real-estate | Residential construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	46,796		38,370		35,690
Loans, net of unearned income, excluding covered loans	46,796		38,696		36,397
Commercial real-estate | Residential construction | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		250		680
Commercial real-estate | Residential construction | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		76		27
Commercial real-estate | Commercial construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		230		844
90+ days and still accruing	0		0		0
Current	209,039		185,513		150,786
Loans, net of unearned income, excluding covered loans	210,031		187,766		151,630
Commercial real-estate | Commercial construction | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		0
Commercial real-estate | Commercial construction | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	992		2,023		0
Commercial real-estate | Land
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	2,646		2,656		2,405
90+ days and still accruing	0		0		0
Current	84,454		86,779		99,445
Loans, net of unearned income, excluding covered loans	89,042		91,830		107,970
Commercial real-estate | Land | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		0		2,682
Commercial real-estate | Land | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,942		2,395		3,438
Commercial real-estate | Office
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	8,243		7,288		6,970
90+ days and still accruing	0		0		0
Current	731,568		694,149		633,655
Loans, net of unearned income, excluding covered loans	743,126		705,432		651,165
Commercial real-estate | Office | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	171		2,621		1,672
Commercial real-estate | Office | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,144		1,374		8,868
Commercial real-estate | Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	3,496		2,392		6,101
90+ days and still accruing	0		0		0
Current	599,050		617,820		615,139
Loans, net of unearned income, excluding covered loans	604,326		623,970		625,060
Commercial real-estate | Industrial | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	61		0		1,114
Commercial real-estate | Industrial | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,719		3,758		2,706
Commercial real-estate | Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	4,975		4,152		9,540
90+ days and still accruing	0		0		0
Current	734,990		723,919		664,584
Loans, net of unearned income, excluding covered loans	742,527		731,488		677,430
Commercial real-estate | Retail | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		116		217
Commercial real-estate | Retail | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,562		3,301		3,089
Commercial real-estate | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,750		249		1,327
90+ days and still accruing	0		0		0
Current	649,589		603,323		570,616
Loans, net of unearned income, excluding covered loans	655,403		605,742		575,763
Commercial real-estate | Multi-family | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	393		249		0
Commercial real-estate | Multi-family | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,671		1,921		3,820
Commercial real-estate | Mixed use and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	8,872		9,638		6,546
90+ days and still accruing	0		0		0
Current	1,532,036		1,443,853		1,337,320
Loans, net of unearned income, excluding covered loans	1,552,563		1,465,117		1,361,236
Commercial real-estate | Mixed use and other | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	808		2,603		6,626
Commercial real-estate | Mixed use and other | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	10,847		9,023		10,744
Commercial real-estate | PCI - commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	[1]	0	[1]	0	[1]
90+ days and still accruing	18,120	[1]	10,976	[1]	21,073	[1]
Current	40,671	[1]	34,327	[1]	45,571	[1]
Loans, net of unearned income, excluding covered loans	66,672	[1],[2]	55,712	[1],[2]	75,604	[1],[2]
Commercial real-estate | PCI - commercial real estate | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,639	[1]	6,393	[1]	2,791	[1]
Commercial real-estate | PCI - commercial real estate | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	3,242	[1]	4,016	[1]	6,169	[1]
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	7,665		6,174		7,311
90+ days and still accruing	0		0		0
Current	698,100		705,623		693,815
Loans, net of unearned income, excluding covered loans	709,283		716,293		707,748
Home equity | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	693		983		1,650
Home equity | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,825		3,513		4,972
Residential real-estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income, excluding covered loans	495,925		483,542		426,769
Residential real-estate | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	14,248		15,502		14,385
90+ days and still accruing	0		0		0
Current	469,826		459,224		403,474
Loans, net of unearned income, excluding covered loans	493,562		481,308		423,694
Residential real-estate | Residential real estate | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	753		267		946
Residential real-estate | Residential real estate | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	8,735		6,315		4,889
Residential real-estate | PCI - residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	[1]	0	[1]	0	[1]
90+ days and still accruing	266	[1]	549	[1]	1,414	[1]
Current	2,013	[1]	1,685	[1]	1,413	[1]
Loans, net of unearned income, excluding covered loans	2,363	[1],[2]	2,234	[1],[2]	3,075	[1],[2]
Residential real-estate | PCI - residential real estate | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	[1]	0	[1]	0	[1]
Residential real-estate | PCI - residential real estate | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	84	[1]	0	[1]	248	[1]
Premium finance receivables
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of unearned income, excluding covered loans	2,319,623		2,350,833		2,208,361
Premium finance receivables | Commercial insurance loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	15,902		12,705		14,517
90+ days and still accruing	8,062		7,665		6,808
Current	2,271,791		2,307,140		2,160,659
Loans, net of unearned income, excluding covered loans	2,319,623		2,350,833		2,208,361
Premium finance receivables | Commercial insurance loans | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	4,476		5,995		5,600
Premium finance receivables | Commercial insurance loans | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	19,392		17,328		20,777
Premium finance receivables | Life insurance loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0		0		0
90+ days and still accruing	0		0		0
Current	1,972,197		1,870,669		1,511,820
Loans, net of unearned income, excluding covered loans	1,986,606		1,884,092		1,516,132
Premium finance receivables | Life insurance loans | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	8,994		13,084		0
Premium finance receivables | Life insurance loans | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	5,415		339		4,312
Premium finance receivables | PCI - life insurance loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	0	[1]	0	[1]	0	[1]
90+ days and still accruing	0	[1]	0	[1]	0	[1]
Current	389,048	[1]	393,479	[1]	413,202	[1]
Loans, net of unearned income, excluding covered loans	389,048	[1],[2]	393,479	[1],[2]	413,202	[1],[2]
Premium finance receivables | PCI - life insurance loans | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	[1]	0	[1]	0	[1]
Premium finance receivables | PCI - life insurance loans | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	[1]	0	[1]	0	[1]
Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	236		277		1,144
90+ days and still accruing	91		119		105
Current	129,084		149,485		157,464
Loans, net of unearned income, excluding covered loans	130,156		151,012		159,496
Consumer and other | 60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	111		293		213
Consumer and other | 30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 634		$ 838		$ 570

[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.