Amount of assets exceed liabilities.

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

This element represents disclosure of the aggregate cash dividends paid to the entity by consolidated subsidiaries.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(b))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.9-06)
-URI http://asc.fasb.org/extlink&oid=6882215&loc=d3e537971-122884

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Balance Type:	debit
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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Period Type:	duration

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- Details

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Balance Type:
Period Type:

- Details

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Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Subsidiary Guarantor Information for Koppers Inc. Senior Notes - Additional Information (Detail) - USD ($)		6 Months Ended
	Jan. 25, 2017	Jun. 30, 2017	Jun. 30, 2016	Feb. 28, 2017
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 400,000,000
Domestic Guarantor Subsidiaries [Member]
Debt Instrument [Line Items]
Cash dividends paid		$ 2,000,000	$ 700,000
Domestic Guarantor Subsidiaries [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		400,000,000
Senior Notes [Member] \| 6.00 percent Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Principal value of Senior Notes	$ 500,000,000
Senior Notes [Member] \| Domestic Guarantor Subsidiaries [Member]
Debt Instrument [Line Items]
Percentage ownership of subsidiary	100.00%
Senior Notes [Member] \| Koppers Inc. [Member]
Debt Instrument [Line Items]
Amount of assets exceeded liabilities		$ 72,000,000