Allowance For Loan Losses, Allowance For Losses On Lending-Related Commitments And Impaired Loans (Summary Of Activity In The Allowance For Credit Losses By Loan Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	$ 12,627	$ 13,402	$ 12,627	$ 13,402
Allowance for credit losses at period end	124,914	132,051	124,914	132,051
Individually evaluated for impairment	31,902	41,360	31,902	41,360
Collectively evaluated for impairment	93,009	90,691	93,009	90,691
Loans acquired with deteriorated credit quality	3	0	3	0
Loans at period end Individually evaluated for impairment	233,014	203,570	233,014	203,570
Collectively evaluated for impairment	10,664,331	9,370,803	10,664,331	9,370,803
Loans acquired with deteriorated credit quality	592,555	698,338	592,555	698,338
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	111,920	117,362	110,381	113,903
Other adjustments	(534)	0	(1,044)	0
Reclassification to/from allowance for unfunded lending-related commitments	626	(66)	953	1,733
Charge-offs	(23,937)	(27,657)	(57,627)	(86,277)
Recoveries	6,020	747	7,884	7,985
Provision for credit losses	18,192	28,263	51,740	81,305
Allowance for loan losses at period end	112,287	118,649	112,287	118,649
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	45	0	45
Allowance for credit losses at period end	27,741	33,825	27,741	33,825
Individually evaluated for impairment	3,168	7,143	3,168	7,143
Collectively evaluated for impairment	24,573	26,682	24,573	26,682
Loans acquired with deteriorated credit quality	0	0	0	0
Loans at period end Individually evaluated for impairment	38,838	32,561	38,838	32,561
Collectively evaluated for impairment	2,726,255	2,296,969	2,726,255	2,296,969
Loans acquired with deteriorated credit quality	5,960	7,568	5,960	7,568
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	26,983	32,847	31,237	31,777
Other adjustments	(138)	0	(142)	0
Reclassification to/from allowance for unfunded lending-related commitments	0	75	45	1,606
Charge-offs	(3,315)	(8,851)	(12,623)	(25,574)
Recoveries	349	150	852	717
Provision for credit losses	3,862	9,559	8,372	25,254
Allowance for loan losses at period end	27,741	33,780	27,741	33,780
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	12,627	13,357	12,627	13,357
Allowance for credit losses at period end	67,712	77,729	67,712	77,729
Individually evaluated for impairment	21,998	30,000	21,998	30,000
Collectively evaluated for impairment	45,714	47,729	45,714	47,729
Loans acquired with deteriorated credit quality	0	0	0	0
Loans at period end Individually evaluated for impairment	160,711	143,975	160,711	143,975
Collectively evaluated for impairment	3,490,161	3,266,989	3,490,161	3,266,989
Loans acquired with deteriorated credit quality	48,840	54,357	48,840	54,357
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	53,801	61,703	56,405	62,618
Other adjustments	(304)	0	(787)	0
Reclassification to/from allowance for unfunded lending-related commitments	626	(141)	908	127
Charge-offs	(17,000)	(14,734)	(34,455)	(48,767)
Recoveries	5,352	299	5,657	1,100
Provision for credit losses	12,610	17,245	27,357	49,294
Allowance for loan losses at period end	55,085	64,372	55,085	64,372
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0	0	0
Allowance for credit losses at period end	13,600	7,117	13,600	7,117
Individually evaluated for impairment	3,011	2,272	3,011	2,272
Collectively evaluated for impairment	10,589	4,845	10,589	4,845
Loans acquired with deteriorated credit quality	0	0	0	0
Loans at period end Individually evaluated for impairment	13,118	16,367	13,118	16,367
Collectively evaluated for impairment	794,474	862,813	794,474	862,813
Loans acquired with deteriorated credit quality	0	0	0	0
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	13,878	7,077	7,712	6,213
Other adjustments	(2)	0	(4)	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0	0	0
Charge-offs	(1,543)	(1,071)	(5,865)	(3,144)
Recoveries	52	32	385	59
Provision for credit losses	1,215	1,079	11,372	3,989
Allowance for loan losses at period end	13,600	7,117	13,600	7,117
Residential Real-Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0	0	0
Allowance for credit losses at period end	7,553	5,213	7,553	5,213
Individually evaluated for impairment	3,244	1,509	3,244	1,509
Collectively evaluated for impairment	4,306	3,704	4,306	3,704
Loans acquired with deteriorated credit quality	3	0	3	0
Loans at period end Individually evaluated for impairment	18,696	9,829	18,696	9,829
Collectively evaluated for impairment	357,326	316,378	357,326	316,378
Loans acquired with deteriorated credit quality	656	0	656	0
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	6,724	5,878	5,028	5,107
Other adjustments	(90)	0	(111)	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0	0	0
Charge-offs	(1,027)	(926)	(1,590)	(2,483)
Recoveries	8	3	13	8
Provision for credit losses	1,938	258	4,213	2,581
Allowance for loan losses at period end	7,553	5,213	7,553	5,213
Premium Finance Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0	0	0
Allowance for credit losses at period end	6,887	6,874	6,887	6,874
Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	6,887	6,874	6,887	6,874
Loans acquired with deteriorated credit quality	0	0	0	0
Loans at period end Individually evaluated for impairment	0	0	0	0
Collectively evaluated for impairment	3,111,533	2,453,239	3,111,533	2,453,239
Loans acquired with deteriorated credit quality	537,032	635,776	537,032	635,776
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	8,522	7,436	7,214	6,319
Other adjustments	0	0	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0	0	0
Charge-offs	(886)	(1,769)	(2,483)	(5,413)
Recoveries	206	159	675	5,814
Provision for credit losses	(955)	1,048	1,481	154
Allowance for loan losses at period end	6,887	6,874	6,887	6,874
Indirect Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0	0	0
Allowance for credit losses at period end	269	612	269	612
Individually evaluated for impairment	1	7	1	7
Collectively evaluated for impairment	268	605	268	605
Loans acquired with deteriorated credit quality	0	0	0	0
Loans at period end Individually evaluated for impairment	69	81	69	81
Collectively evaluated for impairment	77,309	62,371	77,309	62,371
Loans acquired with deteriorated credit quality	0	0	0	0
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	640	613	645	526
Other adjustments	0	0	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0	0	0
Charge-offs	(73)	(24)	(157)	(188)
Recoveries	25	75	76	183
Provision for credit losses	(323)	(52)	(295)	91
Allowance for loan losses at period end	269	612	269	612
Consumer And Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0	0	0
Allowance for credit losses at period end	1,152	681	1,152	681
Individually evaluated for impairment	480	429	480	429
Collectively evaluated for impairment	672	252	672	252
Loans acquired with deteriorated credit quality	0	0	0	0
Loans at period end Individually evaluated for impairment	1,582	757	1,582	757
Collectively evaluated for impairment	107,273	112,044	107,273	112,044
Loans acquired with deteriorated credit quality	67	637	67	637
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	1,372	1,808	2,140	1,343
Other adjustments	0	0	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0	0	0
Charge-offs	(93)	(282)	(454)	(708)
Recoveries	28	29	226	104
Provision for credit losses	(155)	(874)	(760)	(58)
Allowance for loan losses at period end	$ 1,152	$ 681	$ 1,152	$ 681