Fair Values Of Assets And Liabilities (Narrative) (Details) (USD $)																							3 Months Ended												3 Months Ended		3 Months Ended						3 Months Ended
	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011		Mar. 31, 2012 U.S. Treasury [Member]	Dec. 31, 2011 U.S. Treasury [Member]	Mar. 31, 2011 U.S. Treasury [Member]	Mar. 31, 2012 U.S. Government Agencies [Member]	Dec. 31, 2011 U.S. Government Agencies [Member]	Mar. 31, 2011 U.S. Government Agencies [Member]	Mar. 31, 2012 Municipal [Member]	Dec. 31, 2011 Municipal [Member]	Mar. 31, 2011 Municipal [Member]	Mar. 31, 2012 Corporate Notes And Other [Member]	Mar. 31, 2011 Corporate Notes And Other [Member]	Mar. 31, 2012 Mortgage-Backed [Member]	Dec. 31, 2011 Mortgage-Backed [Member]	Mar. 31, 2011 Mortgage-Backed [Member]	Mar. 31, 2012 Equity Securities [Member]	Mar. 31, 2011 Equity Securities [Member]	Mar. 31, 2012 Mortgage Servicing Rights [Member]	Mar. 31, 2012 Mortgage Servicing Rights [Member] Maximum [Member]	Mar. 31, 2012 Mortgage Servicing Rights [Member] Minimum [Member]	Mar. 31, 2012 Other Real Estate Owned [Member]	Mar. 31, 2012 Other Real Estate Owned [Member] Maximum [Member]	Mar. 31, 2012 Other Real Estate Owned [Member] Minimum [Member]	Mar. 31, 2012 Level 3 [Member]	Mar. 31, 2011 Level 3 [Member]	Mar. 31, 2012 Level 3 [Member] Municipal [Member]	Mar. 31, 2011 Level 3 [Member] Municipal [Member]	Mar. 31, 2011 Level 3 [Member] Corporate Notes And Other [Member]	Mar. 31, 2011 Level 3 [Member] Mortgage-Backed [Member]	Mar. 31, 2012 Level 3 [Member] Equity Securities [Member]	Mar. 31, 2011 Level 3 [Member] Equity Securities [Member]	Mar. 31, 2012 Level 3 [Member] Equity Securities [Member] Maximum [Member]	Mar. 31, 2012 Level 3 [Member] Equity Securities [Member] Minimum [Member]	Mar. 31, 2012 Fair Value [Member]	Mar. 31, 2011 Fair Value [Member]	Mar. 31, 2012 Valued Based On Underlying Collateral [Member]	Mar. 31, 2012 Valued Using Discounted Cash Flow Model [Member]	Mar. 31, 2012 Prepayment Speeds [Member] Mortgage Servicing Rights [Member]	Mar. 31, 2012 Prepayment Speeds [Member] Mortgage Servicing Rights [Member] Maximum [Member]	Mar. 31, 2012 Prepayment Speeds [Member] Mortgage Servicing Rights [Member] Minimum [Member]	Mar. 31, 2012 Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2012 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 1,869,344,000		$ 1,291,797,000		$ 1,710,321,000		$ 23,189,000	$ 16,173,000	$ 96,160,000	$ 682,780,000	$ 765,916,000	$ 795,854,000	$ 69,915,000	$ 60,098,000	$ 48,406,000	$ 168,816,000	$ 235,573,000	$ 886,148,000	$ 248,551,000	$ 493,943,000	$ 38,496,000	$ 40,385,000									$ 25,535,000	$ 15,594,000	$ 9,713,000	$ 2,723,000	$ 21,224,000	$ 28,745,000
Discount rate input																							10.26%	13.50%	10.00%	9.30%	60.00%	0.00%							2.09%		2.23%	1.89%					18.99%	24.00%	16.00%
Mortgage servicing rights	7,201,000				9,448,000																								7,201,000	9,448,000
Remaining contractual principal balance outstanding, mortgage loans held-for-sale																																							329,900,000	92,100,000
Mortgage loans held-for-sale	339,600,000				92,151,000
Total impaired loans	251,963,000	[1]	226,538,000	[1]	203,536,000	[1]																																			165,600,000	86,400,000
Other real estate owned																																														$ 76,236,000	$ 76,236,000

[1] Impaired loans are considered by the Company to be non-accrual loans, restructured loans or loans with principal and/or interest at risk, even if the loan is current with all payments of principal and interest.