Securities, Available-for-sale (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	$ 137,407	$ 99,514
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	1,327	431
Investments with an Unrealized Loss of 12 months or longer, Fair Value	180,260	232,495
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	2,247	5,822
Total Investments with an Unrealized Loss, Fair Value	317,667	332,009
Total Investments with an Unrealized Loss, Unrealized Losses	3,574	6,253
US Treasury Securities [Member]
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	0	0
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	0	0
Investments with an Unrealized Loss of 12 months or longer, Fair Value	0	0
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	0	0
Total Investments with an Unrealized Loss, Fair Value	0	0
Total Investments with an Unrealized Loss, Unrealized Losses	0	0
U.S. Government Agency Securities [Member]
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	39,419	3,593
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	570	10
Investments with an Unrealized Loss of 12 months or longer, Fair Value	66,858	103,658
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	1,007	3,644
Total Investments with an Unrealized Loss, Fair Value	106,277	107,251
Total Investments with an Unrealized Loss, Unrealized Losses	1,577	3,654
Mortgage-backed Securities [Member]
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	69,138	91,410
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	639	405
Investments with an Unrealized Loss of 12 months or longer, Fair Value	97,969	102,892
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	1,047	1,835
Total Investments with an Unrealized Loss, Fair Value	167,107	194,302
Total Investments with an Unrealized Loss, Unrealized Losses	1,686	2,240
State and Municipal Securities [Member]
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	12,251	3,561
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	63	15
Investments with an Unrealized Loss of 12 months or longer, Fair Value	6,293	16,502
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	176	257
Total Investments with an Unrealized Loss, Fair Value	18,544	20,063
Total Investments with an Unrealized Loss, Unrealized Losses	239	272
Asset-backed Securities [Member]
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	0	0
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	0	0
Investments with an Unrealized Loss of 12 months or longer, Fair Value	8,988	9,289
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	16	85
Total Investments with an Unrealized Loss, Fair Value	8,988	9,289
Total Investments with an Unrealized Loss, Unrealized Losses	16	85
Corporate Notes [Member]
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	16,599	950
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	55	1
Investments with an Unrealized Loss of 12 months or longer, Fair Value	152	154
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	1	1
Total Investments with an Unrealized Loss, Fair Value	16,751	1,104
Total Investments with an Unrealized Loss, Unrealized Losses	$ 56	$ 2