Fair Value of Financial Instruments - Assets measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value Disclosures
Total securities available for sale:	$ 389,424	$ 289,845
Recurring basis | Level 1
Fair Value Disclosures
Total securities available for sale:	0	0
Recurring basis | Level 2
Fair Value Disclosures
Total securities available for sale:	380,963	280,273
Recurring basis | Level 3
Fair Value Disclosures
Total securities available for sale:	0	0
Recurring basis | Corporate | Level 1
Fair Value Disclosures
Total securities available for sale:	0
Recurring basis | Corporate | Level 2
Fair Value Disclosures
Total securities available for sale:	37,642
Recurring basis | Corporate | Level 3
Fair Value Disclosures
Total securities available for sale:	0
Recurring basis | Municipal bonds | Level 1
Fair Value Disclosures
Total securities available for sale:	0	0
Recurring basis | Municipal bonds | Level 2
Fair Value Disclosures
Total securities available for sale:	118,803	130,245
Recurring basis | Municipal bonds | Level 3
Fair Value Disclosures
Total securities available for sale:	0	0
Recurring basis | Collateralized mortgage obligation: residential | Level 1
Fair Value Disclosures
Total securities available for sale:	0	0
Recurring basis | Collateralized mortgage obligation: residential | Level 2
Fair Value Disclosures
Total securities available for sale:	31,388	24,543
Recurring basis | Collateralized mortgage obligation: residential | Level 3
Fair Value Disclosures
Total securities available for sale:	0	0
Recurring basis | Mortgage-backed securities: residential | Level 1
Fair Value Disclosures
Total securities available for sale:	0	0
Recurring basis | Mortgage-backed securities: residential | Level 2
Fair Value Disclosures
Total securities available for sale:	193,130	125,485
Recurring basis | Mortgage-backed securities: residential | Level 3
Fair Value Disclosures
Total securities available for sale:	0	0
Recurring basis | Estimated Fair Value
Fair Value Disclosures
Total securities available for sale:	380,963	280,273
Recurring basis | Estimated Fair Value | Corporate
Fair Value Disclosures
Total securities available for sale:	37,642
Recurring basis | Estimated Fair Value | Municipal bonds
Fair Value Disclosures
Total securities available for sale:	118,803	130,245
Recurring basis | Estimated Fair Value | Collateralized mortgage obligation: residential
Fair Value Disclosures
Total securities available for sale:	31,388	24,543
Recurring basis | Estimated Fair Value | Mortgage-backed securities: residential
Fair Value Disclosures
Total securities available for sale:	$ 193,130	$ 125,485