Restructuring Charges (Details) - Employee Separation Costs - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Costs incurred and charged to expense	$ 167	$ 501
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	755
Costs incurred and charged to expense	167
Cash payments	(590)
Accrued liability ending balance	$ 332