Fair Value of Financial Instruments - Hierarchy Table - Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Total
Investment securities available-for-sale, at fair value	$ 703,083	$ 380,963
Agency
Total
Investment securities available-for-sale, at fair value	55,071
Corporate
Total
Investment securities available-for-sale, at fair value	54,349	37,642
Municipal bonds
Total
Investment securities available-for-sale, at fair value	252,078	118,803
Collateralized mortgage obligation: residential
Total
Investment securities available-for-sale, at fair value	46,321	31,388
Mortgage-backed securities
Total
Investment securities available-for-sale, at fair value	295,264	193,130
Level 1
Total
Investment securities available-for-sale, at fair value	0	0
Level 2
Total
Investment securities available-for-sale, at fair value	703,083	380,963
Level 3
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis
Total
Investment securities available-for-sale, at fair value	703,083	380,963
Recurring basis | Agency
Total
Investment securities available-for-sale, at fair value	55,071
Recurring basis | Corporate
Total
Investment securities available-for-sale, at fair value	54,349	37,642
Recurring basis | Municipal bonds
Total
Investment securities available-for-sale, at fair value	252,078	118,803
Recurring basis | Collateralized mortgage obligation: residential
Total
Investment securities available-for-sale, at fair value	46,321	31,388
Recurring basis | Mortgage-backed securities
Total
Investment securities available-for-sale, at fair value	295,264	193,130
Recurring basis | Level 1
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 1 | Agency
Total
Investment securities available-for-sale, at fair value	0
Recurring basis | Level 1 | Corporate
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 1 | Municipal bonds
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 1 | Collateralized mortgage obligation: residential
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 1 | Mortgage-backed securities
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 2
Total
Investment securities available-for-sale, at fair value	703,083	380,963
Recurring basis | Level 2 | Agency
Total
Investment securities available-for-sale, at fair value	55,071
Recurring basis | Level 2 | Corporate
Total
Investment securities available-for-sale, at fair value	54,349	37,642
Recurring basis | Level 2 | Municipal bonds
Total
Investment securities available-for-sale, at fair value	252,078	118,803
Recurring basis | Level 2 | Collateralized mortgage obligation: residential
Total
Investment securities available-for-sale, at fair value	46,321	31,388
Recurring basis | Level 2 | Mortgage-backed securities
Total
Investment securities available-for-sale, at fair value	295,264	193,130
Recurring basis | Level 3
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 3 | Agency
Total
Investment securities available-for-sale, at fair value	0
Recurring basis | Level 3 | Corporate
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 3 | Municipal bonds
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 3 | Collateralized mortgage obligation: residential
Total
Investment securities available-for-sale, at fair value	0	0
Recurring basis | Level 3 | Mortgage-backed securities
Total
Investment securities available-for-sale, at fair value	$ 0	$ 0