Discontinued Operations (Summary Of Cash Flow Data Related To Discontinued Operations) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Non-cash investing activities - capital expenditures, consisting of of unpaid capital expenditure liabilities at period end	$ 2,900	$ 3,300
Tile Coatings [Member] | Discontinued Operations [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Depreciation		8,702
Amortization of intangible assets		2,388
Capital expenditures	(3,048)	(9,114)
Non-cash operating activities - goodwill impairment		9,100
Non-cash operating activities - restructuring and impairment charges	1,091	127
Non-cash investing activities - capital expenditures, consisting of of unpaid capital expenditure liabilities at period end	$ 683	$ 738