Allowance For Credit Losses (Summary Of Allocation Of The Allowance For Loan Losses And The Related Loans By Loan Portfolio Segment Disaggregated Based On The Impairment Methodology) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Financing Receivable, Allowance for Credit Losses [Line Items]
Less: Allowance for loan losses	$ 133,802	$ 124,704	$ 101,990
Total	9,799,641	9,365,795
Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	23,243	15,226
Collectively evaluated for impairment	97,031	103,100
Loans acquired with discounts related to credit quality	13,528	6,378
Less: Allowance for loan losses	133,802	124,704
Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	184,075	154,287
Collectively evaluated for impairment	9,343,722	8,854,853
Loans acquired with discounts related to credit quality	271,844	356,655
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Less: Allowance for loan losses	73,649	61,967	49,267
Total	1,962,129	1,946,217
Commercial And Industrial [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	11,105	6,397
Collectively evaluated for impairment	51,588	50,032
Loans acquired with discounts related to credit quality	10,956	5,538
Less: Allowance for loan losses	73,649	61,967
Commercial And Industrial [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	54,858	32,297
Collectively evaluated for impairment	1,823,529	1,792,769
Loans acquired with discounts related to credit quality	83,742	121,151
Total Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Less: Allowance for loan losses	34,637	30,409	25,516
Total	4,152,717	4,018,283
Total Commercial Real Estate [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	8,516	6,141
Collectively evaluated for impairment	23,611	23,776
Loans acquired with discounts related to credit quality	2,510	492
Less: Allowance for loan losses	34,637	30,409
Total Commercial Real Estate [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	107,970	103,322
Collectively evaluated for impairment	3,877,122	3,703,162
Loans acquired with discounts related to credit quality	167,625	211,799
Residential Mortgage Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Less: Allowance for loan losses	9,120	9,476	5,397
Total	2,301,136	1,942,456
Residential Mortgage Loans [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	3,577	2,683
Collectively evaluated for impairment	5,481	6,445
Loans acquired with discounts related to credit quality	62	348
Less: Allowance for loan losses	9,120	9,476
Residential Mortgage Loans [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	21,005	18,585
Collectively evaluated for impairment	2,264,585	1,906,845
Loans acquired with discounts related to credit quality	15,546	17,026
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Less: Allowance for loan losses	8,677	14,499	15,480
Total	1,383,659	1,458,839
Consumer [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	45	5
Collectively evaluated for impairment	8,632	14,494
Less: Allowance for loan losses	8,677	14,499
Consumer [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	242	83
Collectively evaluated for impairment	1,378,486	1,452,077
Loans acquired with discounts related to credit quality	4,931	6,679
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Less: Allowance for loan losses	7,719	8,353	6,330
Unallocated [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Collectively evaluated for impairment	7,719	8,353
Less: Allowance for loan losses	$ 7,719	$ 8,353