Reportable Segments and Geographic Data (Schedule of Operating Assets and Capital Expenditures by Reporting Segment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 1,417,992	$ 1,361,198	$ 1,263,433
Capital expenditures and purchased software	82,886	87,637	73,492
Cash	197,755	183,727	181,742	$ 185,113
Machine Clothing [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	453,836	464,468	454,010
Capital expenditures and purchased software	20,230	20,522	15,651
Engineered Composites [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	633,394	584,076	514,527
Capital expenditures and purchased software	60,121	63,865	54,678
Corporate Expenses [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Capital expenditures and purchased software	2,535	3,250	3,163
Significant Reconciling Items [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Cash	197,755	183,727	181,742
Income taxes prepaid, receivable and deferred	70,095	74,914	74,078
Other assets	$ 62,912	$ 54,013	$ 39,076