Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary Of Recorded Investment Based On Performance Of Loans By Class) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012		Sep. 30, 2012
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	$ 12,581,039		$ 11,828,943		$ 11,489,900
Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	12,457,778		11,710,860		11,372,009
Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	123,261		118,083		117,891
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	3,109,121		2,914,798		2,771,053
Commercial | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	3,091,284		2,893,061		2,753,342
Commercial | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	17,837		21,737		17,711
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,722,551		1,628,203		1,556,375
Commercial | Commercial and industrial | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,707,078		1,608,794		1,541,212
Commercial | Commercial and industrial | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	15,473		19,409		15,163
Commercial | Franchise
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	213,328		196,395		179,706
Commercial | Franchise | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	213,328		194,603		177,914
Commercial | Franchise | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans			1,792		1,792
Commercial | Mortgage warehouse line of credit
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	71,383		215,076		225,295
Commercial | Mortgage warehouse line of credit | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	71,383		215,076		225,295
Commercial | Mortgage warehouse line of credit | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0		0		0
Commercial | Community Advantage - homeowners association
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	90,504		81,496		73,881
Commercial | Community Advantage - homeowners association | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	90,504		81,496		73,881
Commercial | Community Advantage - homeowners association | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0		0		0
Commercial | Aircraft
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	12,601		17,364		21,444
Commercial | Aircraft | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	12,601		17,364		21,016
Commercial | Aircraft | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0		0		428
Commercial | Asset-based lending
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	739,568		572,438		533,061
Commercial | Asset-based lending | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	737,204		571,902		532,733
Commercial | Asset-based lending | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	2,364		536		328
Commercial | Tax exempt
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	148,103		91,824		90,404
Commercial | Tax exempt | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	148,103		91,824		90,404
Commercial | Tax exempt | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0		0		0
Commercial | Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	101,654		90,443		83,351
Commercial | Leases | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	101,654		90,443		83,351
Commercial | Leases | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0		0		0
Commercial | Other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	90		16,549		1,576
Commercial | Other | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	90		16,549		1,576
Commercial | Other | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0		0		0
Commercial | Purchased non-covered commercial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	9,339	[1],[2]	5,010	[1],[2]	5,960	[1],[2]
Commercial | Purchased non-covered commercial | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	9,339	[2]	5,010	[2]	5,960	[2]
Commercial | Purchased non-covered commercial | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	[2]	0	[2]	0	[2]
Commercial real-estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,146,110		3,864,118		3,699,712
Commercial real-estate | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,089,998		3,814,145		3,641,251
Commercial real-estate | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	56,112		49,973		58,461
Commercial real-estate | Residential construction
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	40,330		40,401		44,255
Commercial real-estate | Residential construction | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	35,161		37,291		42,114
Commercial real-estate | Residential construction | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	5,169		3,110		2,141
Commercial real-estate | Commercial construction
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	146,088		170,955		169,543
Commercial real-estate | Commercial construction | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	138,234		168,796		166,228
Commercial real-estate | Commercial construction | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	7,854		2,159		3,315
Commercial real-estate | Land
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	109,251		134,197		133,486
Commercial real-estate | Land | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	105,035		122,898		122,857
Commercial real-estate | Land | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,216		11,299		10,629
Commercial real-estate | Office
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	634,520		569,711		584,321
Commercial real-estate | Office | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	630,202		565,515		578,136
Commercial real-estate | Office | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	4,318		4,196		6,185
Commercial real-estate | Industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	625,012		577,937		574,325
Commercial real-estate | Industrial | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	616,828		575,848		572,440
Commercial real-estate | Industrial | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	8,184		2,089		1,885
Commercial real-estate | Retail
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	612,215		568,896		560,669
Commercial real-estate | Retail | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	600,956		561,104		550,536
Commercial real-estate | Retail | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	11,259		7,792		10,133
Commercial real-estate | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	550,625		396,691		363,423
Commercial real-estate | Multi-family | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	548,022		394,105		360,109
Commercial real-estate | Multi-family | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	2,603		2,586		3,314
Commercial real-estate | Mixed use and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,369,670		1,349,254		1,220,850
Commercial real-estate | Mixed use and other | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,357,161		1,332,512		1,199,991
Commercial real-estate | Mixed use and other | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	12,509		16,742		20,859
Commercial real-estate | Purchased non-covered commercial real-estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	58,399	[1],[2]	56,076	[1],[2]	48,840	[1],[2]
Commercial real-estate | Purchased non-covered commercial real-estate | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	58,399	[2]	56,076	[2]	48,840	[2]
Commercial real-estate | Purchased non-covered commercial real-estate | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	[2]	0	[2]	0	[2]
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	736,620		788,474		807,592
Home equity | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	725,694		774,951		796,088
Home equity | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	10,926		13,523		11,504
Residential real-estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	397,707		367,213		376,678
Residential real-estate | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	396,208		366,357		376,022
Residential real-estate | Residential real estate | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	382,082		354,629		360,629
Residential real-estate | Residential real estate | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	14,126		11,728		15,393
Residential real-estate | Purchased non-covered residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,499	[1],[2]	856	[1],[2]	656	[1],[2]
Residential real-estate | Purchased non-covered residential real estate | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,499	[2]	856	[2]	656	[2]
Residential real-estate | Purchased non-covered residential real estate | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	[2]	0	[2]	0	[2]
Premium finance receivables | Commercial insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	2,150,481		1,987,856		1,982,945
Premium finance receivables | Commercial insurance loans | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	2,128,598		1,968,546		1,969,924
Premium finance receivables | Commercial insurance loans | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	21,883		19,310		13,021
Premium finance receivables | Life insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,409,856		1,210,707		1,128,588
Premium finance receivables | Life insurance loans | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,409,250		1,210,682		1,128,559
Premium finance receivables | Life insurance loans | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	606		25		29
Premium finance receivables | Purchased life insurance loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	459,883	[1],[2]	514,459	[1],[2]	537,032	[1],[2]
Premium finance receivables | Purchased life insurance loans | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	459,883	[2]	514,459	[2]	537,032	[2]
Premium finance receivables | Purchased life insurance loans | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	0	[2]	0	[2]	0	[2]
Indirect consumer
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	57,236		77,333		77,378
Indirect consumer | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	57,056		77,089		77,091
Indirect consumer | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	180		244		287
Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	114,025		103,985		108,922
Consumer and other | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	113,846		101,153		108,855
Consumer and other | Consumer and other | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	112,255		99,610		107,370
Consumer and other | Consumer and other | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	1,591		1,543		1,485
Consumer and other | Purchased non-covered consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	179	[1],[2]	2,832	[1],[2]	67	[1],[2]
Consumer and other | Purchased non-covered consumer and other | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	179	[2]	2,832	[2]	67	[2]
Consumer and other | Purchased non-covered consumer and other | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income, excluding covered loans	$ 0	[2]	$ 0	[2]	$ 0	[2]

[1] Purchased 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] Purchased 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.