Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Severance Costs		$ 3,300		$ 2,900
Restructuring Reserve	$ 2,619	2,840		2,619
Payments for Restructuring				(3,151)
Restructuring charges	0		$ 0	2,930	$ 0
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	892	0		892
Payments for Restructuring				(360)
Restructuring charges				1,252
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	1,727	$ 2,840		1,727
Payments for Restructuring				(2,791)
Restructuring charges				1,678
Accounts Payable and Accrued Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,000			2,000
Other Noncurrent Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 600			$ 600