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
	Mar. 31, 2013	Mar. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	$ 15,287	$ 13,078
Allowance for credit losses at period end	125,635	124,101
Individually evaluated for impairment	29,273	33,467
Collectively evaluated for impairment	96,155	90,634
Loans acquired with deteriorated credit quality	207	0
Loans at period end Individually evaluated for impairment	203,554	251,963
Collectively evaluated for impairment	11,133,896	9,845,919
Loans acquired with deteriorated credit quality	562,862	619,502
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	107,351	110,381
Other adjustments	(229)	(238)
Reclassification to/from allowance for unfunded lending-related commitments	(213)	152
Charge-offs	(13,161)	(15,467)
Recoveries	1,233	1,041
Provision for credit losses	15,367	15,154
Allowance for loan losses at period end	110,348	111,023
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	28,952	33,219
Individually evaluated for impairment	3,682	3,705
Collectively evaluated for impairment	25,270	29,514
Loans acquired with deteriorated credit quality	0	0
Loans at period end Individually evaluated for impairment	27,447	29,158
Collectively evaluated for impairment	2,840,405	2,509,353
Loans acquired with deteriorated credit quality	4,843	5,945
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	28,794	31,237
Other adjustments	(3)	(3)
Reclassification to/from allowance for unfunded lending-related commitments	0	45
Charge-offs	(4,540)	(3,262)
Recoveries	295	257
Provision for credit losses	4,406	4,945
Allowance for loan losses at period end	28,952	33,219
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	15,287	13,078
Allowance for credit losses at period end	71,695	67,030
Individually evaluated for impairment	23,089	25,336
Collectively evaluated for impairment	48,409	41,694
Loans acquired with deteriorated credit quality	197	0
Loans at period end Individually evaluated for impairment	145,203	197,221
Collectively evaluated for impairment	3,790,445	3,336,217
Loans acquired with deteriorated credit quality	54,817	52,322
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	52,135	56,405
Other adjustments	(217)	(222)
Reclassification to/from allowance for unfunded lending-related commitments	(213)	107
Charge-offs	(3,299)	(8,229)
Recoveries	368	131
Provision for credit losses	7,634	5,760
Allowance for loan losses at period end	56,408	53,952
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	12,122	7,920
Individually evaluated for impairment	1,748	3,056
Collectively evaluated for impairment	10,374	4,864
Loans acquired with deteriorated credit quality	0	0
Loans at period end Individually evaluated for impairment	16,057	14,495
Collectively evaluated for impairment	743,161	825,869
Loans acquired with deteriorated credit quality	0	0
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	12,734	7,712
Other adjustments	0	1
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(2,397)	(2,590)
Recoveries	162	162
Provision for credit losses	1,623	2,635
Allowance for loan losses at period end	12,122	7,920
Residential Real-Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	5,140	5,551
Individually evaluated for impairment	598	1,362
Collectively evaluated for impairment	4,532	4,189
Loans acquired with deteriorated credit quality	10	0
Loans at period end Individually evaluated for impairment	12,984	10,791
Collectively evaluated for impairment	346,835	349,879
Loans acquired with deteriorated credit quality	833	657
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	5,560	5,028
Other adjustments	(9)	(14)
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(1,728)	(175)
Recoveries	5	2
Provision for credit losses	1,312	710
Allowance for loan losses at period end	5,140	5,551
Premium Finance Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	6,071	8,108
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	6,071	8,108
Loans acquired with deteriorated credit quality	0	0
Loans at period end Individually evaluated for impairment	0	0
Collectively evaluated for impairment	3,250,941	2,645,989
Loans acquired with deteriorated credit quality	499,731	560,404
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	6,096	7,214
Other adjustments	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(1,068)	(850)
Recoveries	294	298
Provision for credit losses	749	1,446
Allowance for loan losses at period end	6,071	8,108
Indirect Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	277	643
Individually evaluated for impairment	3	7
Collectively evaluated for impairment	274	636
Loans acquired with deteriorated credit quality	0	0
Loans at period end Individually evaluated for impairment	58	77
Collectively evaluated for impairment	69,187	67,368
Loans acquired with deteriorated credit quality	0	0
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	267	645
Other adjustments	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(32)	(51)
Recoveries	15	30
Provision for credit losses	27	19
Allowance for loan losses at period end	277	643
Consumer And Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	1,378	1,630
Individually evaluated for impairment	153	1
Collectively evaluated for impairment	1,225	1,629
Loans acquired with deteriorated credit quality	0	0
Loans at period end Individually evaluated for impairment	1,805	221
Collectively evaluated for impairment	92,922	111,244
Loans acquired with deteriorated credit quality	2,638	174
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses at beginning of period	1,765	2,140
Other adjustments	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(97)	(310)
Recoveries	94	161
Provision for credit losses	(384)	(361)
Allowance for loan losses at period end	$ 1,378	$ 1,630