Securities (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale securities
Less Than 12 Months, Fair Value	$ 188,000	$ 251,814
Less Than 12 Months, Unrealized Losses	974	1,249
12 Months Or Longer, Fair Value	278,021	376,719
12 Months Or Longer, Unrealized Losses	6,249	10,846
Total Fair Value	466,021	628,533
Total Unrealized Losses	7,223	12,095
Held-to-maturity debt securities
Less Than 12 Months, Fair Value	10,079	15,095
Less Than 12 Months, Unrealized Losses	63	37
Total Fair Value	10,079	15,095
Total Unrealized Losses	63	37
Obligations of U.S. Government sponsored entities [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	37,667	71,363
Less Than 12 Months, Unrealized Losses	90	385
12 Months Or Longer, Fair Value	17,550	65,497
12 Months Or Longer, Unrealized Losses	143	1,317
Total Fair Value	55,217	136,860
Total Unrealized Losses	233	1,702
Held-to-maturity debt securities
Less Than 12 Months, Fair Value	10,079	15,095
Less Than 12 Months, Unrealized Losses	63	37
Total Fair Value	10,079	15,095
Total Unrealized Losses	63	37
Obligations of U.S. states and political subdivisions [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	16,833	15,451
Less Than 12 Months, Unrealized Losses	140	124
12 Months Or Longer, Fair Value	2,142	8,102
12 Months Or Longer, Unrealized Losses	20	155
Total Fair Value	18,975	23,553
Total Unrealized Losses	160	279
Residential Mortgage-backed securities U.S. Government agencies [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	2,455	2,623
Less Than 12 Months, Unrealized Losses	4	21
12 Months Or Longer, Fair Value	36,556	28,502
12 Months Or Longer, Unrealized Losses	848	1,323
Total Fair Value	39,011	31,125
Total Unrealized Losses	852	1,344
Residential Mortgage-backed securities U.S. Government sponsored entities [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	131,045	162,377
Less Than 12 Months, Unrealized Losses	740	719
12 Months Or Longer, Fair Value	218,656	271,503
12 Months Or Longer, Unrealized Losses	4,855	7,665
Total Fair Value	349,701	433,880
Total Unrealized Losses	5,595	8,384
U.S. corporate debt securities [Member]
Available-for-sale securities
12 Months Or Longer, Fair Value	2,162	2,163
12 Months Or Longer, Unrealized Losses	338	338
Total Fair Value	2,162	2,163
Total Unrealized Losses	338	338
Equity securities [Member]
Available-for-sale securities
12 Months Or Longer, Fair Value	955	952
12 Months Or Longer, Unrealized Losses	45	48
Total Fair Value	955	952
Total Unrealized Losses	$ 45	$ 48