Securities - (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Amortized Cost
Due within one year	$ 51,995
Due after one year through five years	78,507
Due after five years through ten years	213,069
Due after ten years	127,026
Amortized Cost	470,597	430,163
Fair Value
Due within one year	52,081
Due after one year through five years	80,593
Due after five years through ten years	218,280
Due after ten years	135,670
Fair Value	486,624	442,488
Amortized Cost
Due within one year	0
Due after one year through five years	1,059
Due after five years through ten years	5,054
Due after ten years	26,057
Amortized Cost	541,734	553,770
Amortized Cost	541,734
Fair Value
Due within one year	0
Due after one year through five years	1,127
Due after five years through ten years	5,104
Due after ten years	20,126
Securities available for sale	545,797	553,584
Other debt securities
Amortized Cost
Amortized Cost	16,999	17,517
Fair Value
Securities available for sale	17,494	17,930
Other equity securities
Amortized Cost
Amortized Cost	2,331	2,331
Other equity securities	2,331
Fair Value
Securities available for sale	3,660	3,599
Government agency mortgage backed securities | Residential mortgage backed securities:
Amortized Cost
Amortized Cost	292,587	292,283
Fair Value
Securities available for sale	298,082	296,359
Government agency mortgage backed securities | Commercial mortgage backed securities:
Amortized Cost
Amortized Cost	42,019	45,714
Fair Value
Securities available for sale	43,570	47,185
Government agency collateralized mortgage obligations | Residential mortgage backed securities:
Amortized Cost
Amortized Cost	151,075	158,436
Fair Value
Securities available for sale	151,808	157,436
Government agency collateralized mortgage obligations | Commercial mortgage backed securities:
Amortized Cost
Amortized Cost	4,553	4,970
Fair Value
Securities available for sale	$ 4,826	$ 5,172