Employee Benefit Plans - Net Periodic Pension Cost of Defined Benefit Plan (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Employee Benefits and Share-based Compensation, Noncash [Abstract]
Service cost	$ 172	$ 94	$ 219	$ 206
Interest cost	34	18	63	31
Amortization of prior service cost	21	21	42	42
Net periodic benefit cost	$ 227	$ 133	$ 324	$ 279