Restructuring Costs (Details) - USD ($) $ in Thousands		12 Months Ended			16 Months Ended
	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Restructuring Reserve [Roll Forward]
Restructuring costs (Note 3)		$ 8,008	$ 2,661	$ 1,032
Inventory Write-down	$ 32,500
Gain (Loss) on Disposition of Business		5,722	0	0
Distribution
Restructuring Reserve [Roll Forward]
Severance Costs		600	500	700
Distribution | Voluntary Retirement Program
Restructuring Reserve [Roll Forward]
Severance Costs				300
Aerospace
Restructuring Reserve [Roll Forward]
Severance Costs		1,400	400	$ 2,500
Corporate, Non-Segment
Restructuring Reserve [Roll Forward]
Severance Costs			2,800
2017 Announced Restructuring Plan [Member]
Restructuring Reserve [Roll Forward]
Restructuring accrual balance at December 31, 2017	1,351	1,351
Provision		4,751
Cash payments		(4,499)
Changes in foreign currency exchange rates		(23)
Restructuring accrual balance at December 31, 2018		1,580	1,351		$ 1,580
Expected restructuring costs		9,200			9,200
Restructuring costs (Note 3)		6,000	2,700		8,700
Inventory Write-down		800	1,000
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost		400
Effect on Future Earnings, Amount		4,000
2017 Announced Restructuring Plan [Member] | Employee Severance
Restructuring Reserve [Roll Forward]
Restructuring accrual balance at December 31, 2017	1,172	1,172
Provision		1,893
Cash payments		(2,034)
Changes in foreign currency exchange rates		(9)
Restructuring accrual balance at December 31, 2018		1,022	1,172		1,022
2017 Announced Restructuring Plan [Member] | Other Restructuring
Restructuring Reserve [Roll Forward]
Restructuring accrual balance at December 31, 2017	$ 179	179
Provision		2,858
Cash payments		(2,465)
Changes in foreign currency exchange rates		(14)
Restructuring accrual balance at December 31, 2018		558	$ 179		558
U.K. Composites [Member]
Restructuring Reserve [Roll Forward]
Accounts, Notes, Loans and Financing Receivable, Net, Current		200			200
Notes, Loans and Financing Receivable, Gross, Noncurrent		2,300			$ 2,300
U.K. Composites [Member] | Aerospace
Restructuring Reserve [Roll Forward]
Gain (Loss) on Disposition of Business		5,700
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax		(1,700)
Engineering Services [Member] | Aerospace
Restructuring Reserve [Roll Forward]
Gain (Loss) on Disposition of Assets		$ 700