Investment Securities - Summary of Amortized Cost and Fair Value by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Amortized Cost
Available-for-sale: Due in one year or less	$ 5,074
Available-for-sale: Due after one year through five years	19,498
Available-for-sale: Due after five years through ten years	9,540
Available-for-sale: Due after ten years	2,388
Mortgage-backed securities and collateralized mortgage obligations: Residential	237,632
Mortgage-backed securities and collateralized mortgage obligations: Commercial	5,653
Mutual funds	2,100
Available-for-sale, Amortized Cost	281,885	$ 272,588
Fair Value
Available-for-sale: Due in one year or less	5,114
Available-for-sale: Due after one year through five years	20,120
Available-for-sale: Due after five years through ten years	9,832
Available-for-sale: Due after ten years	2,365
Mortgage-backed securities and collateralized mortgage obligations: Residential	240,321
Mortgage-backed securities and collateralized mortgage obligations: Commercial	5,617
Mutual funds	2,116
Available-for-sale, Fair Value	285,485	276,984
Amortized Cost
Held-to-maturity: Due in one year or less	473
Held-to-maturity: Due after one year through five years	2,923
Held-to-maturity: Due after five years through ten years	11,105
Held-to-maturity: Due after ten years	29,432
Mortgage-backed securities and collateralized mortgage obligations: Residential	69,704
Mortgage-backed securities and collateralized mortgage obligations: Commercial	7,406
Held-to-maturity, Amortized Cost	121,043	141,201
Fair Value
Held-to-maturity: Due in one year or less	475
Held-to-maturity: Due after one year through five years	2,960
Held-to-maturity: Due after five years through ten years	11,273
Held-to-maturity: Due after ten years	29,739
Mortgage-backed securities and collateralized mortgage obligations: Residential	70,584
Mortgage-backed securities and collateralized mortgage obligations: Commercial	7,457
Held-to-maturity, Fair Value	$ 122,488	$ 141,593