Employee Benefits and Stock Compensation - Summary of Stock Options Outstanding and Exercisable (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares granted	297,576	243,391	63,650
Equity Option [Member]
Options, Outstanding at January 1, 2017	778,778
Shares granted	297,576
Options, Exercised	(91,468)
Options, Forfeited	(33,537)
Options, Outstanding at December 31, 2017	951,349	778,778
Options, Exercisable at December 31, 2017	517,100
Weighted-Average Exercise Price, Outstanding at January 1, 2017	$ 15.86
Weighted-Average Exercise Price, Granted	28.21
Weighted-Average Exercise Price, Exercised	11.77
Weighted-Average Exercise Price, Forfeited	96.17
Weighted-Average Exercise Price, Outstanding at December 31, 2017	17.29	$ 15.86
Weighted-Average Exercise Price, Exercisable at December 31, 2017	$ 12.09
Weighted-Average Remaining Contractual Term, Outstanding	6 years 10 months 10 days
Weighted-Average Remaining Contractual Term, Exercisable at December 31, 2017	5 years 10 months 6 days
Aggregate Intrinsic Value, Outstanding at December 31, 2017	$ 8,493
Aggregate Intrinsic Value, Exercisable at December 31, 2017	$ 6,787