Employee Benefit Plans - Benefit Obligations of Defined Benefit Plan (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year	$ 2,747	$ 1,187
Service cost	47	112
Interest cost	29	13
Benefit obligation, end of year	$ 2,823	$ 1,312