Plant Closures and Divestitures - Additional Information (Detail) |
Dec. 31, 2016 |
Nov. 30, 2016 |
Mar. 31, 2016 |
Jul. 31, 2015 |
|---|---|---|---|---|
| Discontinued Operations Disposed Of By Means Other Than Sale [Member] | China [Member] | Carbon Materials and Chemicals [Member] | ||||
| Restructuring Cost and Reserve [Line Items] | ||||
| Percentage of operations in Tangshan, China owned by the company | 60.00% | |||
| Tangshan Koppers Kailuan Carbon Chemical Company Limited [Member] | ||||
| Restructuring Cost and Reserve [Line Items] | ||||
| Ownership percentage | 30.00% | 30.00% | ||
| KSA Limited Partnership [Member] | ||||
| Restructuring Cost and Reserve [Line Items] | ||||
| Ownership percentage | 50.00% |