Restructuring - Actual and Estimated Pre-Tax Expenses (Details) - Technical Nonwovens - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Total estimated expenses					$ 5,000
Total pre-tax expense incurred	$ 885	$ 534	$ 2,081	$ 662
Estimated remaining expense at June 30, 2018	2,919		2,919	4,338
Severance and Related Expenses
Restructuring Cost and Reserve [Line Items]
Total estimated expenses					1,200
Total pre-tax expense incurred	185	315	681	181
Estimated remaining expense at June 30, 2018	519		519	1,019
Contract Termination Expenses
Restructuring Cost and Reserve [Line Items]
Total estimated expenses					300
Total pre-tax expense incurred	0	0	154	154
Estimated remaining expense at June 30, 2018	146		146	146
Facility Exit, Move and Set-up Expenses
Restructuring Cost and Reserve [Line Items]
Total estimated expenses					$ 3,500
Total pre-tax expense incurred	700	$ 219	1,246	327
Estimated remaining expense at June 30, 2018	$ 2,254		$ 2,254	$ 3,173