Quarterly Financial Data (Schedule of Quarterly Data) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net sales	$ 251,600	$ 251,900	$ 255,400	$ 223,600	$ 226,700	$ 222,100	$ 215,600	$ 199,300	$ 213,000	$ 191,300	$ 203,200	$ 172,300	$ 982,479	$ 863,717	$ 779,839
Gross profit	87,900	92,400	91,700	77,700	77,500	79,600	63,200	76,000	77,500	72,600	78,500	72,700	349,749	296,283	301,284
Operating income	37,400	40,800	42,200	17,000									137,408	78,676	94,132
Net income/(loss) attributable to the Company	$ 17,600	$ 27,700	$ 29,900	$ 7,700	$ 5,900	$ 15,300	$ 1,100	$ 10,800	$ 15,700	$ 13,100	$ 10,400	$ 13,500	$ 82,891	$ 33,111	$ 52,733
Basic earnings per share	$ 0.54	$ 0.86	$ 0.93	$ 0.24	$ 0.19	$ 0.47	$ 0.03	$ 0.34	$ 0.49	$ 0.41	$ 0.32	$ 0.42	$ 2.57	$ 1.03	$ 1.64
Diluted earnings per share	0.54	0.86	0.93	0.24	0.19	0.47	0.03	0.34	0.49	0.41	0.32	0.42	2.57	1.03	1.64
Cash dividends per share	$ 0.18	$ 0.17	$ 0.17	$ 0.17	0.17	0.17	0.17	0.17	0.17	0.17	0.17	0.17	$ 0.69	$ 0.68	$ 0.68
Machine Clothing [Member]
Net sales	$ 150,700	$ 157,600	$ 161,800	$ 141,800									$ 611,900
Gross profit	73,300	78,700	79,100	66,300									297,400
Operating income	42,900	49,700	50,300	26,900									169,800
Engineered Composites [Member]
Net sales	100,900	94,300	93,600	81,800									370,600
Gross profit	14,700	13,700	12,600	11,500									52,500
Operating income	6,600	3,600	4,100	2,300									16,600
Corporate expenses [Member]
Gross profit	(100)	0	0	(100)									(200)
Operating income	$ (12,100)	$ (12,500)	$ (12,200)	$ (12,200)									$ (49,000)
Maximum [Member]
Class A Common Stock prices:	$ 78.31	$ 81.40	$ 65.45	$ 67.30	65.25	57.60	53.40	49.05	49.25	43.78	41.31	38.21
Minimum [Member]
Class A Common Stock prices:	$ 58.41	$ 60.70	$ 58.35	$ 60.05	$ 56.45	$ 50.25	$ 43.90	$ 43.90	$ 38.65	$ 38.92	$ 37.27	$ 31.43