Fair Value Measurements - Fair Value Measurement on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Fair Value	$ 976,095	$ 810,530
U.S. Treasury and U.S. Government-sponsored agencies
Assets
Fair Value	101,603	13,442
Municipal securities
Assets
Fair Value	158,864	250,015
Residential mortgage-backed securities
Assets
Fair Value	331,602	280,211
Commercial mortgage-backed securities
Assets
Fair Value	333,761	217,079
Collateralized loan obligations
Assets
Fair Value		4,580
Corporate obligations
Assets
Fair Value	25,563	16,770
Other securities
Assets
Fair Value	24,702	28,433
Recurring
Assets
Fair Value	976,095	810,530
Derivative assets - interest rate swaps	5,095	3,418
Liabilities
Derivative liabilities - interest rate swaps	5,095	3,418
Recurring | U.S. Treasury and U.S. Government-sponsored agencies
Assets
Fair Value	101,603	13,442
Recurring | Municipal securities
Assets
Fair Value	158,864	250,015
Recurring | Residential mortgage-backed securities
Assets
Fair Value	331,602	280,211
Recurring | Commercial mortgage-backed securities
Assets
Fair Value	333,761	217,079
Recurring | Collateralized loan obligations
Assets
Fair Value		4,580
Recurring | Corporate obligations
Assets
Fair Value	25,563	16,770
Recurring | Other securities
Assets
Fair Value	24,702	28,433
Recurring | Level 1
Assets
Fair Value	15,936	146
Derivative assets - interest rate swaps	0	0
Liabilities
Derivative liabilities - interest rate swaps	0	0
Recurring | Level 1 | U.S. Treasury and U.S. Government-sponsored agencies
Assets
Fair Value	15,936	0
Recurring | Level 1 | Municipal securities
Assets
Fair Value	0	0
Recurring | Level 1 | Residential mortgage-backed securities
Assets
Fair Value	0	0
Recurring | Level 1 | Commercial mortgage-backed securities
Assets
Fair Value	0	0
Recurring | Level 1 | Collateralized loan obligations
Assets
Fair Value		0
Recurring | Level 1 | Corporate obligations
Assets
Fair Value	0	0
Recurring | Level 1 | Other securities
Assets
Fair Value		146
Recurring | Level 2
Assets
Fair Value	960,159	810,384
Derivative assets - interest rate swaps	5,095	3,418
Liabilities
Derivative liabilities - interest rate swaps	5,095	3,418
Recurring | Level 2 | U.S. Treasury and U.S. Government-sponsored agencies
Assets
Fair Value	85,667	13,442
Recurring | Level 2 | Municipal securities
Assets
Fair Value	158,864	250,015
Recurring | Level 2 | Residential mortgage-backed securities
Assets
Fair Value	331,602	280,211
Recurring | Level 2 | Commercial mortgage-backed securities
Assets
Fair Value	333,761	217,079
Recurring | Level 2 | Collateralized loan obligations
Assets
Fair Value		4,580
Recurring | Level 2 | Corporate obligations
Assets
Fair Value	25,563	16,770
Recurring | Level 2 | Other securities
Assets
Fair Value	24,702	28,287
Recurring | Level 3
Assets
Fair Value	0	0
Derivative assets - interest rate swaps	0	0
Liabilities
Derivative liabilities - interest rate swaps	0	0
Recurring | Level 3 | U.S. Treasury and U.S. Government-sponsored agencies
Assets
Fair Value	0	0
Recurring | Level 3 | Municipal securities
Assets
Fair Value	0	0
Recurring | Level 3 | Residential mortgage-backed securities
Assets
Fair Value	0	0
Recurring | Level 3 | Commercial mortgage-backed securities
Assets
Fair Value	0	0
Recurring | Level 3 | Collateralized loan obligations
Assets
Fair Value		0
Recurring | Level 3 | Corporate obligations
Assets
Fair Value	0	0
Recurring | Level 3 | Other securities
Assets
Fair Value	$ 0	$ 0