Restructuring (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated to date	50
Restructuring charges accrued	$ 900	$ 10,700	$ 12,700
Restructuring expense	6,200
Curtailment gain	500	700
Restructuring reserve, current	1,342	5,534
Restructuring reserve, noncurrent	700	100
Restructuring 2016 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges accrued	3,900	1,000	1,600
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	100	1,100	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 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			$ 2,800
AEC facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	3,100	1,900
Write-off of equipment	$ 1,200
AEC facility non cash [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 1,700