Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Severance Costs		$ 3,300		$ 2,900
Restructuring Reserve	$ 3,709	2,840		3,709
Payments for Restructuring				(2,061)
Restructuring charges	2,495		$ 0	2,930	$ 0
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	950	0		950
Payments for Restructuring				(302)
Restructuring charges				1,252
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,759	$ 2,840		2,759
Payments for Restructuring				(1,759)
Restructuring charges				1,678
Accounts Payable and Accrued Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,800			2,800
Other Noncurrent Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 900			$ 900