Restructuring Activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	$ 391	$ 309
Amounts expensed	0	61
Amounts paid	(109)	(184)
Restructuring liability, ending balance	$ 282	$ 186