Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Retirement Benefits [Abstract]
Service cost	$ 65	$ 338	$ 195	$ 1,014
Interest cost	151	117	453	351
Net periodic benefit cost	$ 216	$ 455	$ 648	$ 1,365