Amount of expense for allocation of cost of tangible asset over its useful life directly used in production of good and rendering of service.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(2))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
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Nature of Operations (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Sep. 30, 2019
Unallocated Corporate [Member]
Segment Reporting Information [Line Items]
Cost of goods sold for accelerated depreciation of property, plant, machinery and equipment		$ 5.6
Mineral Fiber [Member]
Segment Reporting Information [Line Items]
Cost of goods sold for accelerated depreciation of property, plant, machinery and equipment	$ 14.1	$ 4.0
WAVE [Member]
Segment Reporting Information [Line Items]
Equity interest percentage			50.00%	50.00%