Employee Benefit Plans - Net Periodic Pension Cost of Defined Benefit Plan (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Employee Benefits and Share-based Compensation, Noncash [Abstract]
Service cost	$ 47	$ 112
Interest cost	29	13
Amortization of prior service cost	21	21
Net periodic benefit cost	$ 97	$ 146