Restructuring (Narrative) (Details) $ in Thousands	12 Months Ended			48 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated to date	50			50
Restructuring charges accrued	$ 10,700	$ 11,800		$ 14,800
Restructuring expense	6,100
Restructuring reserve, current	5,534	2,714		5,534
Restructuring reserve, noncurrent	100	600		100
Curtailment gain	700
Accrued restructuring costs expected to be paid within one year	1,900			$ 1,900
Former Employee [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges accrued	1,000	1,600
Reduced Employee Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges accrued		800	$ 2,600
Machine Clothing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		1,100
Write-off of equipment			$ 2,200
AEC assets [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	1,700	$ 5,000
Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	200
Write-off of intangible assets and equipment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	4,500
Cost of goods sold for write-off of inventory [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 2,800