Investment Securities - Summary of Amortized Cost and Fair Value by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Amortized Cost
Available-for-sale: Due in one year or less	$ 5,108
Available-for-sale: Due after one year through five years	19,960
Available-for-sale: Due after five years through ten years	10,733
Available-for-sale: Due after ten years	2,391
Mortgage-backed securities and collateralized mortgage obligations: Residential	248,609
Mortgage-backed securities and collateralized mortgage obligations: Commercial	9,552
Mutual funds	2,100
Available-for-sale, Amortized Cost	298,453	$ 272,588
Fair Value
Available-for-sale: Due in one year or less	5,174
Available-for-sale: Due after one year through five years	20,666
Available-for-sale: Due after five years through ten years	11,062
Available-for-sale: Due after ten years	2,343
Mortgage-backed securities and collateralized mortgage obligations: Residential	249,485
Mortgage-backed securities and collateralized mortgage obligations: Commercial	9,509
Mutual funds	2,096
Available-for-sale, Fair Value	300,335	276,984
Amortized Cost
Held-to-maturity: Due in one year or less	111
Held-to-maturity: Due after one year through five years	3,294
Held-to-maturity: Due after five years through ten years	11,145
Held-to-maturity: Due after ten years	29,578
Mortgage-backed securities and collateralized mortgage obligations: Residential	73,387
Mortgage-backed securities and collateralized mortgage obligations: Commercial	9,014
Held-to-maturity, Amortized Cost	126,529	141,201
Fair Value
Held-to-maturity: Due in one year or less	111
Held-to-maturity: Due after one year through five years	3,322
Held-to-maturity: Due after five years through ten years	11,158
Held-to-maturity: Due after ten years	29,550
Mortgage-backed securities and collateralized mortgage obligations: Residential	73,671
Mortgage-backed securities and collateralized mortgage obligations: Commercial	9,037
Held-to-maturity, Fair Value	$ 126,849	$ 141,593