Loans (Unallocated Portion of the Allowance for Loan Losses) (Details) (USD $) In Thousands	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009
Portion of the allowance for loan losses	$ 122,741	$ 124,321	$ 126,316	$ 125,442	$ 125,369	$ 125,309
Commercial And Industrial [Member]
Portion of the allowance for loan losses	56,566	52,800	57,789	65,293	63,576	57,394
Commercial Real Estate [Member]
Portion of the allowance for loan losses	20,901	24,551	28,534	31,229	30,259	28,514
Consumer Real Estate [Member]
Portion of the allowance for loan losses	3,683	3,485	3,223	2,467	2,430	2,560
Consumer And Other [Member]
Portion of the allowance for loan losses	12,611	12,941	11,974	18,763	19,689	16,929
Unallocated [Member]
Portion of the allowance for loan losses	28,980	30,544	24,796	7,690	9,415	19,912
Unallocated [Member] | Excessive Industry Concentrations [Member]
Portion of the allowance for loan losses	2,054		1,720	1,940
Unallocated [Member] | Large Relationship Concentrations [Member]
Portion of the allowance for loan losses	2,170		2,127	1,557
Unallocated [Member] | Highly - Leveraged Credit Relationships [Member]
Portion of the allowance for loan losses	3,249
Unallocated [Member] | Policy Exceptions [Member]
Portion of the allowance for loan losses	2,180		2,414	2,635
Unallocated [Member] | Credit And Collateral Exceptions [Member]
Portion of the allowance for loan losses	1,800		557	953
Unallocated [Member] | Loans Not Reviewed By Concurrence [Member]
Portion of the allowance for loan losses	9,196
Unallocated [Member] | Adjustment For Recoveries [Member]
Portion of the allowance for loan losses	(11,393)
Unallocated [Member] | General Macroeconomic Risk [Member]
Portion of the allowance for loan losses	$ 19,724		$ 17,978	$ 605