Aggregate divestiture cost.

No definition available.

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- Definition

Expected period for sales adjustment

+ References

No definition available.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 230
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- Definition

Amount after tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

+ References

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- Definition

Amount of costs of goods sold attributable to disposal group, including, but not limited to, discontinued operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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

+ References

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- Definition

Increase (decrease) in cash associated with the entity's discontinued operations.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Discontinued Operations - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Feb. 18, 2020
Schedule Of Equity Method Investments [Line Items]
Net Cash Provided by (Used in) Discontinued Operations	$ (0.3)	$ 2.2
Impairment charge	0.0
Aggregate disvestiture cost	1.0
Koppers (Jiangsu) Carbon Chemical Company Limited [Member]
Schedule Of Equity Method Investments [Line Items]
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	107.0
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	45.0
Net Cash Provided by (Used in) Discontinued Operations	$ 65.0
Koppers (Jiangsu) Carbon Chemical Company Limited [Member] \| Minimum [Member]
Schedule Of Equity Method Investments [Line Items]
Expected period for sales adjustment	4 months
Koppers (Jiangsu) Carbon Chemical Company Limited [Member] \| Maximum [Member]
Schedule Of Equity Method Investments [Line Items]
Expected period for sales adjustment	6 months
Koppers (Jiangsu) Carbon Chemical Company Limited [Member] \| Carbon Materials and Chemicals [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership percentage			75.00%