Securities, Available-for-sale (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	$ 165,653	$ 213,232
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	1,857	5,292
Investments with an Unrealized Loss of 12 months or longer, Fair Value	214,711	156,735
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	15,275	19,101
Total Investments with an Unrealized Loss, Fair Value	380,364	369,967
Total Investments with an Unrealized Loss, Unrealized Losses	17,132	24,393
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	4,910	8,742
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	14	22
Investments with an Unrealized Loss of 12 months or longer, Fair Value	96,804	92,869
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	9,467	13,400
Total Investments with an Unrealized Loss, Fair Value	101,714	101,611
Total Investments with an Unrealized Loss, Unrealized Losses	9,481	13,422
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	133,216	157,262
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	1,172	3,913
Investments with an Unrealized Loss of 12 months or longer, Fair Value	92,296	42,903
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	5,114	4,889
Total Investments with an Unrealized Loss, Fair Value	225,512	200,165
Total Investments with an Unrealized Loss, Unrealized Losses	6,286	8,802
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	26,778	46,282
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	670	1,351
Investments with an Unrealized Loss of 12 months or longer, Fair Value	9,630	3,798
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	467	555
Total Investments with an Unrealized Loss, Fair Value	36,408	50,080
Total Investments with an Unrealized Loss, Unrealized Losses	1,137	1,906
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	15,823	17,006
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	226	255
Total Investments with an Unrealized Loss, Fair Value	15,823	17,006
Total Investments with an Unrealized Loss, Unrealized Losses	226	255
Corporate Notes [Member]
Available-for-sale securities, continuous unrealized loss position [Abstract]
Investments with an Unrealized Loss of less than 12 months, Fair Value	749	946
Investments with an Unrealized Loss of less than 12 months, Unrealized Losses	1	6
Investments with an Unrealized Loss of 12 months or longer, Fair Value	158	159
Investments with an Unrealized Loss of 12 months or longer, Unrealized Losses	1	2
Total Investments with an Unrealized Loss, Fair Value	907	1,105
Total Investments with an Unrealized Loss, Unrealized Losses	$ 2	$ 8