Stock Based Compensation - Stock Options Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Option Shares
Outstanding at beginning of period (in shares)			13,200
Business combinations options acquired (in shares)			40,753
Granted (in shares)			0
Exercised (in shares)	(17,330)	(28,710)	(30,530)	(32,010)
Forfeited (in shares)			(1,660)
Expired (in shares)			0
Outstanding at end of period (in shares)	21,763		21,763
Exercisable at end of period (in shares)	17,264		17,264
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)			$ 21.97
Business combination options acquired (in dollars per share)			16.63
Granted (in dollars per share)			0.00
Exercised (in dollars per share)			18.94
Forfeited (in dollars per share)			16.63
Expired (in dollars per share)			0.00
Outstanding at end of period (in dollars per share)	$ 16.63		16.63
Exercisable at end of period (in dollars per share)	$ 16.63		$ 16.63
Weighted Average Remaining Contractual Term
Outstanding at end of period			5 years 24 days
Exercisable at end of period			4 years 11 months 15 days
Aggregate Intrinsic Value ($000)
Outstanding at end of period	$ 481		$ 481
Exercisable at end of period	$ 382		$ 382