Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	$ 339,620	$ 254,666
Less than 12 Months Unrealized Losses	(7,584)	(5,923)
12 Months or More Fair Value	12,418	13,378
12 Months or More Unrealized Losses	(314)	(377)
Total Fair Value	352,038	268,044
Total Unrealized Losses	(7,898)	(6,300)
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	160,587	167,739
Less than 12 Months Unrealized Losses	(5,914)	(5,090)
12 Months or More Fair Value	11,250	12,204
12 Months or More Unrealized Losses	(267)	(336)
Total Fair Value	171,837	179,943
Total Unrealized Losses	(6,181)	(5,426)
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	21,513	20,413
Less than 12 Months Unrealized Losses	(584)	(383)
12 Months or More Fair Value	210	210
12 Months or More Unrealized Losses	(5)	(5)
Total Fair Value	21,723	20,623
Total Unrealized Losses	(589)	(388)
US Government Corporations and Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	137,814	56,600
Less than 12 Months Unrealized Losses	(981)	(435)
12 Months or More Fair Value	0	0
12 Months or More Unrealized Losses	0	0
Total Fair Value	137,814	56,600
Total Unrealized Losses	(981)	(435)
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	19,706	9,914
Less than 12 Months Unrealized Losses	(105)	(15)
12 Months or More Fair Value	0	0
12 Months or More Unrealized Losses	0	0
Total Fair Value	19,706	9,914
Total Unrealized Losses	(105)	(15)
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months Fair Value	0	0
Less than 12 Months Unrealized Losses	0	0
12 Months or More Fair Value	958	964
12 Months or More Unrealized Losses	(42)	(36)
Total Fair Value	958	964
Total Unrealized Losses	$ (42)	$ (36)