Fair Values Of Assets And Liabilities (Summary Of Balances Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $)	Jun. 30, 2011		Dec. 31, 2010	Jun. 30, 2010
Available-for-sale securities	$ 1,456,426,000		$ 1,496,302,000	$ 1,418,035,000
US Treasury [Member]
Available-for-sale securities	100,737,000		96,097,000
US Treasury [Member] | Level 2 [Member]
Available-for-sale securities	100,737,000			117,013,000
US Treasury [Member] | Fair Value [Member]
Available-for-sale securities	100,737,000			117,013,000
US Government Agencies [Member]
Available-for-sale securities	683,690,000		884,055,000
US Government Agencies [Member] | Level 2 [Member]
Available-for-sale securities	683,690,000			796,937,000
US Government Agencies [Member] | Fair Value [Member]
Available-for-sale securities	683,690,000			796,937,000
Municipal Securities [Member]
Available-for-sale securities	49,457,000		52,303,000
Municipal Securities [Member] | Level 2 [Member]
Available-for-sale securities	24,932,000			37,864,000
Municipal Securities [Member] | Level 3 [Member]
Available-for-sale securities	24,525,000			14,028,000
Municipal Securities [Member] | Fair Value [Member]
Available-for-sale securities	49,457,000			51,892,000
Corporate Notes and Other [Member] | Level 2 [Member]
Available-for-sale securities	197,939,000			63,643,000
Corporate Notes and Other [Member] | Level 3 [Member]
Available-for-sale securities	16,313,000			11,352,000
Corporate Notes and Other [Member] | Fair Value [Member]
Available-for-sale securities	214,252,000			74,995,000
Mortgage-Backed [Member]
Available-for-sale securities	365,323,000		161,681,000
Mortgage-Backed [Member] | Level 2 [Member]
Available-for-sale securities	362,639,000			196,219,000
Mortgage-Backed [Member] | Level 3 [Member]
Available-for-sale securities	2,684,000			145,331,000
Mortgage-Backed [Member] | Fair Value [Member]
Available-for-sale securities	365,323,000			341,550,000
Equity Securities [Member] | Level 2 [Member]
Available-for-sale securities	12,076,000	[1]		8,757,000	[1]
Equity Securities [Member] | Level 3 [Member]
Available-for-sale securities	30,891,000	[1]		26,891,000	[1]
Equity Securities [Member] | Fair Value [Member]
Available-for-sale securities	42,967,000	[1]		35,648,000	[1]
Level 1 [Member]
Trading account securities				53,000
Assets, Total				53,000
Level 2 [Member]
Trading account securities	337,000			1,399,000
Mortgage loans held-for-sale	133,083,000			222,703,000
Nonqualified deferred compensations assets	4,564,000			3,135,000
Derivative assets	20,996,000			16,450,000
Assets, Total	1,540,993,000			1,464,120,000
Derivative Liabilties	30,589,000			35,656,000
Level 3 [Member]
Trading account securities	172,000			36,809,000
Mortgage servicing rights	8,762,000			5,347,000
Assets, Total	83,347,000			239,758,000
Fair Value [Member]
Trading account securities	509,000			38,261,000
Mortgage loans held-for-sale	133,083,000			222,703,000
Mortgage servicing rights	8,762,000			5,347,000
Nonqualified deferred compensations assets	4,564,000			3,135,000
Derivative assets	20,996,000			16,450,000
Assets, Total	1,624,340,000			1,703,931,000
Derivative Liabilties	30,589,000			35,656,000
Remaining contractual principal balance outstanding, mortgage loans held-for-sale	$ 129,600,000			$ 213,900,000

[1] Excludes the common securities issued by trusts formed by the Company in conjunction with Trust Preferred Securities offerings.