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	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans acquired with discounts related to credit quality	$ 117,000
Total	11,149,522	9,799,641
Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	19,870	23,243
Collectively evaluated for impairment	99,472	97,031
Loans acquired with discounts related to credit quality	13,528	13,528
Total	132,870	133,802
Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	182,063	184,075
Collectively evaluated for impairment	9,555,576	9,343,722
Loans acquired with discounts related to credit quality	1,411,883	271,844
Total	11,149,522	9,799,641
Commercial And Industrial [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	9,628	11,105
Collectively evaluated for impairment	52,727	51,588
Loans acquired with discounts related to credit quality	10,956	10,956
Total	73,311	73,649
Commercial And Industrial [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	51,529	54,858
Collectively evaluated for impairment	1,810,606	1,823,529
Loans acquired with discounts related to credit quality	379,000	83,742
Total	2,241,135	1,962,129
Total Commercial Real Estate [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	7,357	8,516
Collectively evaluated for impairment	24,548	23,611
Loans acquired with discounts related to credit quality	2,510	2,510
Total	34,415	34,637
Total Commercial Real Estate [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	111,295	107,970
Collectively evaluated for impairment	3,888,128	3,877,122
Loans acquired with discounts related to credit quality	941,310	167,625
Total	4,940,733	4,152,717
Residential Mortgage [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	2,864	3,577
Collectively evaluated for impairment	6,911	5,481
Loans acquired with discounts related to credit quality	62	62
Total	9,837	9,120
Residential Mortgage [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	18,962	21,005
Collectively evaluated for impairment	2,493,001	2,264,585
Loans acquired with discounts related to credit quality	33,841	15,546
Total	2,545,804	2,301,136
Consumer [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	21	45
Collectively evaluated for impairment	7,919	8,632
Total	7,940	8,677
Consumer [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	277	242
Collectively evaluated for impairment	1,363,841	1,378,486
Loans acquired with discounts related to credit quality	57,732	4,931
Total	1,421,850	1,383,659
Unallocated [Member] | Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Collectively evaluated for impairment	7,367	7,719
Total	$ 7,367	$ 7,719