Restructuring Costs (Details) - USD ($) $ in Thousands		12 Months Ended			28 Months Ended
	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Restructuring Reserve [Roll Forward]
Restructuring costs (Note 5)		$ 1,558	$ 7,353	$ 2,661
Inventory Write-down	$ 32,500
Depreciation		21,300	20,900	19,800
Gain (Loss) on Disposition of Business		3,739	5,722	0
Severance Costs		900	1,400
Employee Severance
Restructuring Reserve [Roll Forward]
Accrued Salaries		500			$ 500
Aerospace
Restructuring Reserve [Roll Forward]
Severance Costs			400
Corporate, Non-Segment
Restructuring Reserve [Roll Forward]
Severance Costs			1,600
2017 Announced Restructuring Plan [Member]
Restructuring Reserve [Roll Forward]
Restructuring accrual balance at December 31, 2018		1,580
Provision		183
Cash payments		(1,379)
Changes in foreign currency exchange rates		(7)
Restructuring accrual balance at December 31, 2019		377	1,580		377
Expected restructuring costs		9,500			9,500
Actual Savings Achieved by Exit Plan		8,000
Restructuring costs (Note 5)		600	6,000	2,700	9,300
Inventory Write-down		300	800	$ 1,000
Depreciation		100
Share-based Payment Arrangement, Accelerated Cost		400
2017 Announced Restructuring Plan [Member] | Employee Severance
Restructuring Reserve [Roll Forward]
Restructuring accrual balance at December 31, 2018		1,022
Provision		(15)
Cash payments		(999)
Changes in foreign currency exchange rates		(8)
Restructuring accrual balance at December 31, 2019		0	1,022		0
2017 Announced Restructuring Plan [Member] | Other Restructuring
Restructuring Reserve [Roll Forward]
Restructuring accrual balance at December 31, 2018		558
Provision		198
Cash payments		(380)
Changes in foreign currency exchange rates		1
Restructuring accrual balance at December 31, 2019		377	558		$ 377
U.K. Composites [Member]
Restructuring Reserve [Roll Forward]
Accounts, Notes, Loans and Financing Receivable, Net, Current			200
Financing Receivable, before Allowance for Credit Loss, Noncurrent			2,300
U.K. Composites [Member] | Aerospace
Restructuring Reserve [Roll Forward]
Gain (Loss) on Disposition of Business		$ 3,700	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