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
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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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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Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Topic 230
-SubTopic 10
-Section 45
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Nature of Operations (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019	Sep. 30, 2019
Segment Reporting Information [Line Items]
Gain related to sale of fixed and intangible assets	$ 21.0
Idled Plant
Segment Reporting Information [Line Items]
Gain related to sale of fixed and intangible assets	$ 21.0
Mineral Fiber [Member]
Segment Reporting Information [Line Items]
Cost of goods sold for accelerated depreciation of property, plant, machinery and equipment		$ 14.1
WAVE [Member]
Segment Reporting Information [Line Items]
Equity interest percentage	50.00%		50.00%	50.00%