Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	$ 242,695	$ 163,559
Less than 12 Months Unrealized Losses	(2,023)	(3,130)
12 Months or More Fair Value	2,116	4,348
12 Months or More Unrealized Losses	(65)	(318)
Total Fair Value	244,811	167,907
Total Unrealized Losses	(2,088)	(3,448)
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	238,875	86,529
Less than 12 Months Unrealized Losses	(1,999)	(1,025)
12 Months or More Fair Value	196	588
12 Months or More Unrealized Losses	(1)	(2)
Total Fair Value	239,071	87,117
Total Unrealized Losses	(2,000)	(1,027)
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	3,820	74,755
Less than 12 Months Unrealized Losses	(24)	(2,099)
12 Months or More Fair Value	950	2,792
12 Months or More Unrealized Losses	(34)	(284)
Total Fair Value	4,770	77,547
Total Unrealized Losses	(58)	(2,383)
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	0	2,275
Less than 12 Months Unrealized Losses	0	(6)
12 Months or More Fair Value	970	968
12 Months or More Unrealized Losses	(30)	(32)
Total Fair Value	970	3,243
Total Unrealized Losses	$ (30)	$ (38)