Koppers (KOP) 10-K2 Mar 152014 FY Annual reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Jan. 31, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	KOP
Entity Registrant Name	Koppers Holdings Inc.
Entity Central Index Key	1315257
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		20,495,011
Entity Public Float			$765.30

Consolidated_Statement_of_Oper

Consolidated Statement of Operations (USD $)	12 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Net sales	$1,555	$1,478.30	$1,555
Cost of sales (excluding items below)	1,343.70	1,264.70	1,324.60
Depreciation and amortization	44	29.7	27.6
Impairment and restructuring charges	17.9	11.9	0.6
Selling, general and administrative expenses	116.2	71.7	75.6
Operating profit (loss)	33.2	100.3	126.6
Other income	0	3.5	1.9
Interest expense	39.1	26.8	27.9
(Loss) income before income taxes	-5.9	77	100.6
Income taxes	34.1	36.8	33.3
(Loss) income from continuing operations	-40	40.2	67.3
Income (loss) from discontinued operations, net of tax benefit (expense) of $(1.0), $0.1 and $0.2	0.6	-0.1	-0.1
Net (loss) income	-39.4	40.1	67.2
Net (loss) income attributable to noncontrolling interests	-7	-0.3	1.6
Net (loss) income attributable to Koppers	($32.40)	$40.40	$65.60
Basic -
Continuing operations	($1.61)	$1.96	$3.18
Discontinued operations	$0.03	$0	($0.01)
(Loss) earnings per basic common share	($1.58)	$1.96	$3.17
Diluted -
Continuing operations	($1.61)	$1.94	$3.14
Discontinued operations	$0.03	$0	($0.01)
(Loss) earnings per diluted common share	($1.58)	$1.94	$3.13
Weighted average common shares outstanding (in thousands):
Basic	20,463	20,575	20,681
Diluted	20,463	20,815	20,927
Dividends declared per common share	$1	$1	$0.96

Consolidated_Statement_of_Oper1

Consolidated Statement of Operations (Parenthetical) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Income (loss) from discontinued operations, tax benefit	($1)	$0.10	$0.20

Consolidated_Statement_of_Comp

Consolidated Statement of Comprehensive (Loss) Income (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net (loss) income	($39.40)	$40.10	$67.20
Changes in other comprehensive income (loss):
Currency translation adjustment	-26	-0.6	4
Foreign currency transactions of long-term subsidiary investments	-4.6	-9.4	1.8
Change in derivative financial instrument net loss, net of tax benefit (expense) of $2.6, $0.0 and $0.0	-3.8	0	0
Unrecognized pension transition asset, net of tax benefit (expense) of $0.0, $0.0 and $0.1	0	0	-0.3
Unrecognized pension prior service (benefit) cost, net of tax benefit (expense) of $0.1, $(0.7) and $0.0	-0.2	1.1	0
Unrecognized pension net (loss) gain, net of tax benefit (expense) of $8.0, $(12.8) and $(2.3)	-15.9	21.3	2.8
Total comprehensive (loss) income	-89.9	52.5	75.5
Comprehensive (loss) income attributable to noncontrolling interests	-7.4	0.2	1.8
Comprehensive (loss) income attributable to Koppers	($82.50)	$52.30	$73.70

Consolidated_Statement_of_Comp1

Consolidated Statement of Comprehensive (Loss) Income (Parenthetical) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Tax benefit (expense), derivative financial instrument	$2.60	$0	$0
Unrecognized pension transition asset, tax benefit (expense)	0	0	0.1
Unrecognized pension prior service cost, tax benefit (expense)	0.1	-0.7	0
Unrecognized pension net gain (loss), tax benefit (expense)	$8	($12.80)	($2.30)

Consolidated_Balance_Sheet

Consolidated Balance Sheet (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets
Cash and cash equivalents	$51.10	$82.20
Accounts receivable, net of allowance of $5.6 and $3.6	198.7	157.9
Income tax receivable	0	9
Inventories, net	241.2	168.8
Deferred tax assets	10.5	10
Loan to related party	9.5	9.5
Other current assets	30.3	35.7
Total current assets	541.3	473.1
Equity in non-consolidated investments	5	6.6
Property, plant and equipment, net	299.7	197
Goodwill	247.2	72.7
Intangible assets, net	167.7	12.2
Deferred tax assets	7.8	9.3
Other assets	25.2	14
Total assets	1,293.90	784.9
Liabilities
Accounts payable	120.6	107.6
Accrued liabilities	122.5	82.4
Dividends payable	5.1	5.1
Current maturities of long-term debt	43.9	0
Total current liabilities	292.1	195.1
Long-term debt	806.6	303.1
Accrued postretirement benefits	54.7	41.6
Deferred tax liabilities	10.2	14.7
Other long-term liabilities	46.4	40.6
Total liabilities	1,210	595.1
Commitments and contingent liabilities (Note 20)
Equity
Senior Convertible Preferred Stock, $0.01 par value per share; 10,000,000 shares authorized; no shares issued	0	0
Common Stock, $0.01 par value per share; 40,000,000 shares authorized; 21,938,260 and 21,722,492 shares issued	0.2	0.2
Additional paid-in capital	164.5	158.9
Retained earnings	18	71.3
Accumulated other comprehensive loss	-60.3	-10.2
Treasury stock, at cost; 1,443,248 and 1,390,494 shares	-52.4	-50.4
Total Koppers shareholders' equity	70	169.8
Noncontrolling interests	13.9	20
Total equity	83.9	189.8
Total liabilities and equity	$1,293.90	$784.90

Consolidated_Balance_Sheet_Par

Consolidated Balance Sheet (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$5.60	$3.60
Senior Convertible Preferred Stock, par value	$0.01	$0.01
Senior Convertible Preferred Stock, shares authorized	10,000,000	10,000,000
Senior Convertible Preferred Stock, shares issued	0	0
Common stock, par value	$0.01	$0.01
Common Stock, shares authorized	40,000,000	40,000,000
Common Stock, shares issued	21,938,260	21,722,492
Treasury stock, shares	1,443,248	1,390,494

Consolidated_Statement_of_Cash

Consolidated Statement of Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash (used in) provided by operating activities
Net income	($39.40)	$40.10	$67.20
Adjustments to reconcile net cash provided by operating activities:
Depreciation and amortization	44	29.7	27.6
Impairment charges	4.7	11.9	0.6
Deferred income taxes	2.5	19.5	8
Equity loss (income), net of dividends received	1.6	-0.8	-0.8
(Gain) loss on sale of assets	0	-2.3	0.1
Change in other liabilities	-10.3	-16.4	-11.2
Non-cash interest expense	4.2	1.7	1.7
Stock-based compensation	4.7	4.3	6.9
Other	1	0.5	-1.1
Decrease (increase) in working capital:
Accounts receivable	13.4	2.9	-0.2
Inventories	-14	21.6	-26.5
Accounts payable	-10.6	4.9	-0.1
Accrued liabilities and other working capital	33.7	0	5.6
Net cash provided by operating activities	35.5	117.6	77.8
Cash provided by (used in) investing activities
Capital expenditures	-83.8	-72.9	-28.9
Acquisitions, net of cash acquired	-496.5	-2.3	-14
Net cash proceeds from loan to related party	0	0	2.2
Net cash proceeds from divestitures and asset sales	0.3	2.9	0.8
Net cash used in investing activities	-580	-72.3	-39.9
Cash provided by (used in) financing activities
Borrowings of revolving credit	572.5	97.9	259.4
Repayments of revolving credit	-368	-97.9	-265.8
Borrowings of long-term debt	343	6.6	0
Issuances of Common Stock	0.7	0.2	1.5
Repurchases of Common Stock	-2	-17.5	-8.1
Proceeds from issuance of noncontrolling interest	1.4	2.3	3.7
Excess tax benefit from employee stock plans	0	0.5	1.6
Payment of deferred financing costs	-11.1	-1.3	-0.1
Dividends paid	-20.4	-21.1	-19.5
Net cash provided by (used in) financing activities	516.1	-30.3	-27.3
Effect of exchange rates on cash	-2.7	0.5	2
Net (decrease) increase in cash and cash equivalents	-31.1	15.5	12.6
Cash and cash equivalents at beginning of year	82.2	66.7	54.1
Cash and cash equivalents at end of period	51.1	82.2	66.7
Cash paid during the year for:
Interest	32.9	25.1	26
Income taxes	$16.10	$20.50	$13.60

Consolidated_Statement_of_Shar

Consolidated Statement of Shareholders' Equity (USD $)	Total	Senior Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Deficit) [Member]	Currency Translation Adjustment [Member]	Unrecognized Losses on Cash Flow Hedges [Member]	Unrecognized Pension Transition Assets [Member]	Unrecognized Prior Service Cost [Member]	Unrecognized Pension Net Loss [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Koppers Shareholder's Equity - End of Year [Member]	Noncontrolling Interests [Member]
In Millions	Total	Senior Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Deficit) [Member]	Currency Translation Adjustment [Member]	Unrecognized Losses on Cash Flow Hedges [Member]	Unrecognized Pension Transition Assets [Member]	Unrecognized Prior Service Cost [Member]	Unrecognized Pension Net Loss [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Koppers Shareholder's Equity - End of Year [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2011		$0	$0.20	$142.90	$6.70	$28.80	$0	$0.30	($0.20)	($59.10)		($24.80)		$12.40
Net (loss) income attributable to noncontrolling interests	1.6													1.6
Net (loss) income attributable to Koppers	65.6				65.6
Change in currency translation adjustment excluding foreign currency transactions of long-term subsidiary investments	4					3.9
Reclassification of unrealized losses on cash flow hedges to expense, net of tax benefit of $0.2, $0.0 and $0.0							0
Reclassification of unrecognized prior service (benefit) cost to (income) expense, net of tax (benefit) expense of $(0.1), $0.1 and $0.0									0
Reclassification of unrecognized pension net loss to expense, net of tax expense of $1.4, $2.8 and $3.1										5.3
Employee stock plans				10.4
Reclassification of unrecognized pension transition asset to expense, net of tax (benefit) of $0.0, $0.0 and $(0.1)	-0.3							-0.3
Purchases												-8.1
Investment in noncontrolling interests														3.3
Common Stock dividends					-20.3
Change in foreign currency transactions of long-term subsidiary investments	1.8					1.8
Change in deferred losses on cash flow hedges, net of tax (benefit) of $(2.8), $0.0 and $0.0							0
Revaluation of unrecognized pension prior service cost, net of tax expense of $0.0, $0.6 and $0.0									0
Revaluation of unrecognized pension net loss, net of tax (benefit) expense of $(9.4), $10.0 and $(0.9)										-2.5
Currency translation adjustment														0.2
Total equity - end of year	168.1
Balance at Dec. 31, 2012		0	0.2	153.3	52	34.5	0	0	-0.2	-56.3	-22	-32.9	150.6	17.5
Net (loss) income attributable to noncontrolling interests	-0.3													-0.3
Net (loss) income attributable to Koppers	40.4				40.4
Change in currency translation adjustment excluding foreign currency transactions of long-term subsidiary investments	-0.6					-1.1
Reclassification of unrealized losses on cash flow hedges to expense, net of tax benefit of $0.2, $0.0 and $0.0							0
Reclassification of unrecognized prior service (benefit) cost to (income) expense, net of tax (benefit) expense of $(0.1), $0.1 and $0.0									0.1
Reclassification of unrecognized pension net loss to expense, net of tax expense of $1.4, $2.8 and $3.1										4.7
Employee stock plans				5.6
Reclassification of unrecognized pension transition asset to expense, net of tax (benefit) of $0.0, $0.0 and $(0.1)	0							0
Purchases												-17.5
Investment in noncontrolling interests														2.3
Common Stock dividends					-21.1
Change in foreign currency transactions of long-term subsidiary investments	-9.4					-9.4
Change in deferred losses on cash flow hedges, net of tax (benefit) of $(2.8), $0.0 and $0.0							0
Revaluation of unrecognized pension prior service cost, net of tax expense of $0.0, $0.6 and $0.0									0.9
Revaluation of unrecognized pension net loss, net of tax (benefit) expense of $(9.4), $10.0 and $(0.9)										16.6
Currency translation adjustment														0.5
Total equity - end of year	189.8
Balance at Dec. 31, 2013	169.8	0	0.2	158.9	71.3	24	0	0	0.8	-35	-10.2	-50.4	169.8	20
Net (loss) income attributable to noncontrolling interests	-7													-7
Net (loss) income attributable to Koppers	-32.4				-32.4
Change in currency translation adjustment excluding foreign currency transactions of long-term subsidiary investments	-26					-25.7
Reclassification of unrealized losses on cash flow hedges to expense, net of tax benefit of $0.2, $0.0 and $0.0							0.3
Reclassification of unrecognized prior service (benefit) cost to (income) expense, net of tax (benefit) expense of $(0.1), $0.1 and $0.0									-0.1
Reclassification of unrecognized pension net loss to expense, net of tax expense of $1.4, $2.8 and $3.1										2.4
Employee stock plans				5.6
Reclassification of unrecognized pension transition asset to expense, net of tax (benefit) of $0.0, $0.0 and $(0.1)	0							0
Purchases												-2
Investment in noncontrolling interests														1.3
Common Stock dividends					-20.9
Change in foreign currency transactions of long-term subsidiary investments	-4.6					-4.6
Change in deferred losses on cash flow hedges, net of tax (benefit) of $(2.8), $0.0 and $0.0							-4.1
Revaluation of unrecognized pension prior service cost, net of tax expense of $0.0, $0.6 and $0.0									0
Revaluation of unrecognized pension net loss, net of tax (benefit) expense of $(9.4), $10.0 and $(0.9)										-18.3
Currency translation adjustment														-0.4
Total equity - end of year	83.9
Balance at Dec. 31, 2014	$70			$164.50	$18	($6.30)	($3.80)	$0	$0.70	($50.90)	($60.30)	($52.40)	$70	$13.90

Consolidated_Statement_of_Shar1

Consolidated Statement of Shareholders' Equity (Parenthetical) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Unrecognized pension transition asset, tax (benefit)	$0	$0	($0.10)
Unrecognized Losses on Cash Flow Hedges [Member]
Unrealized losses on cash flow hedges to expense, tax benefit	0.2	0	0
Deferred losses on cash flow hedges, tax (benefit)	-2.8	0	0
Unrecognized Pension Transition Assets [Member]
Unrecognized pension transition asset, tax (benefit)	0	0	-0.1
Unrecognized Prior Service Cost [Member]
Reclassification of unrecognized pension prior service cost, tax expense	-0.1	0.1	0
Revaluation of unrecognized pension prior service cost, tax expense	0	0.6	0
Unrecognized Pension Net Loss [Member]
Reclassification of unrecognized pension net loss, tax expense	1.4	2.8	3.1
Revaluation of unrecognized pension net loss, tax expense (benefit)	($9.40)	$10	($0.90)

Description_of_Business

Description of Business	12 Months Ended
Description of Business	Dec. 31, 2014
Accounting Policies [Abstract]
Description of Business	1. Description of Business
	Parent company of Koppers Inc. – In these financial statements, unless otherwise indicated or the context requires otherwise, when the terms “Koppers,” the “Company,” “we,” “our” or “us,” are used, they mean Koppers Holdings Inc. (“Koppers Holdings”) and its subsidiaries on a consolidated basis. The use of these terms is not intended to imply that Koppers Holdings and Koppers Inc. are not separate and distinct legal entities from each other and from their respective subsidiaries. Koppers Holdings has no direct operations and no significant assets other than the stock of Koppers Inc. It depends on the dividends from the earnings of Koppers Inc. and its subsidiaries to generate the funds necessary to meet its financial obligations. The terms of Koppers Inc.’s revolving credit facility prohibit Koppers Inc. from paying dividends and otherwise transferring assets except for certain limited dividends. Further, the terms of the indenture governing Koppers Inc.’s Senior Notes significantly restrict Koppers Inc. from paying dividends and otherwise transferring assets to Koppers Holdings.
	Business description – The Company is a global integrated producer of carbon compounds and treated and untreated wood products and services for use in a variety of markets including the aluminum, railroad, specialty chemical, utility, rubber concrete, steel, residential lumber and agriculture industries. The Company’s business is operated through three business segments, Carbon Materials and Chemicals, Railroad and Utility Products and Services, and Performance Chemicals.
	The Company’s Carbon Materials and Chemicals segment is primarily a manufacturer of carbon pitch, naphthalene, phthalic anhydride, creosote and carbon black feedstock. Carbon pitch is a critical raw material used in the production of aluminum and for the production of steel in electric arc furnaces. Naphthalene is used for the production of phthalic anhydride and as a surfactant in the production of concrete. Phthalic anhydride is used in the production of plasticizers, polyester resins and alkyd paints. Creosote is used in the treatment of wood and carbon black feedstock is used in the production of carbon black.
	The Company’s Railroad and Utility Products and Services segment sells treated and untreated wood products, rail joint bars and services primarily to the railroad industry and treated wood products to the utility industry. Railroad products include procuring and treating items such as crossties, switch ties and various types of lumber used for railroad bridges and crossings and the manufacture of rail joint bars. Utility products include transmission and distribution poles and pilings. The segment also produces concrete crossties through a joint venture.
	The Company’s Performance Chemicals segment develops, manufactures, and markets wood preservation chemicals and wood treatment technologies and services a diverse range of end-markets including infrastructure, residential and commercial construction, and agriculture.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies

	Basis of presentation – The consolidated financial statements include the accounts of the Company and all majority-owned subsidiaries for which the Company is deemed to exercise control over its operations. All significant intercompany transactions have been eliminated in consolidation. The Company’s investments in 20 percent to 50 percent-owned companies in which it has the ability to exercise significant influence over operating and financial policies are accounted for using the equity method of accounting. Accordingly, the Company’s share of the earnings of these companies is included in the accompanying consolidated statement of income. Certain prior period amounts in the notes to the consolidated financial statements have been reclassified to conform to the current period’s presentation.

	Use of estimates – Accounting principles generally accepted in the U.S. require management to make estimates and judgments that affect the reported amounts of assets and liabilities and the disclosure of contingencies on the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Estimates have been prepared on the basis of the most current and best available information and actual results could differ materially from these estimates.

	Foreign currency translation – For consolidated entities outside of the U.S. that prepare financial statements in currencies other than the U.S. dollar, results of operations and cash flows are translated at average exchange rates during the period, and asset and liabilities are translated at end-of-period exchange rates. Cumulative translation adjustments are included as a separate component of accumulated other comprehensive loss in shareholders’ equity.



	Foreign currency transaction gains and losses result from transactions denominated in a currency which is different than the currency used by the entity to prepare its financial statements. Foreign currency transaction gains (losses) were $0.6 million, $(0.5) million and $(1.7) million for the years ended December 31, 2014, 2013 and 2012, respectively.

	Revenue recognition – The Company recognizes revenue when the risks and rewards of ownership and title to the product have transferred to the customer. Revenue recognition generally occurs at the point of shipment; however in certain circumstances as shipping terms dictate, revenue is recognized at the point of destination. Shipping and handling costs are included as a component of cost of sales.

	The Company recognizes revenue related to the procurement of certain untreated railroad crossties upon transfer of title to the customer, which occurs upon delivery to the Company’s plant and acceptance by the customer. Service revenue, consisting primarily of wood treating services, is recognized at the time the service is provided. Payment on sales of untreated railroad crossties and wood treating services are generally due within 30 days of the invoice date. The Company’s recognition of revenue with respect to untreated crossties meets all the recognition criteria of Securities and Exchange Commission Staff Accounting Bulletin Topic 13.A.3., including transfer of title and risk of ownership, the existence of fixed purchase commitments and delivery schedules established by the customer, and the completion of all performance obligations by the Company. Revenue recognized for untreated crosstie sales for the years ended December 31, 2014, 2013 and 2012 amounted to $93.4 million, $108.3 million and $109.0 million, respectively.

	Research and development – Research and development costs are expensed as incurred and are included in selling, general and administrative expenses. These costs totaled $3.1 million in 2014, $2.4 million in 2013 and $2.3 million in 2012.

	Cash and cash equivalents – Cash and cash equivalents include cash on hand and on deposit and investments in highly liquid investments with an original maturity of 90 days or less.

	Accounts receivable – The Company maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. In circumstances where the Company becomes aware of a specific customer’s inability to meet its financial obligations to Koppers, a specific reserve for bad debts is recorded against amounts due. If the financial condition of the Company’s customers were to deteriorate, resulting in an inability to make payments, additional allowances may be required.

	Inventories – Inventories are carried at lower of cost or market on a worldwide basis. In the U.S., inventory cost (excluding miscellaneous types of inventory) is determined primarily utilizing the last-in, first-out (“LIFO”) basis. Inventory cost outside the U.S. is determined utilizing the first-in, first-out (“FIFO”) basis. Market represents replacement cost for raw materials and net realizable value for work in process and finished goods. LIFO inventories constituted approximately 61 percent and 62 percent of the FIFO inventory value at December 31, 2014 and 2013, respectively.

	Property, plant and equipment – Property, plant and equipment are recorded at purchased cost and include improvements which significantly increase capacities or extend useful lives of existing plant and equipment. Depreciation expense is calculated by applying the straight-line method over estimated useful lives. Estimated useful lives for buildings generally range from 10 to 20 years and depreciable lives for machinery and equipment generally range from 3 to 10 years. Net gains and losses related to asset disposals are recognized in earnings in the period in which the disposal occurs. Routine repairs, replacements and maintenance are expensed as incurred.

	The Company periodically evaluates whether current facts and circumstances indicate that the carrying value of its depreciable long-lived assets may not be recoverable. If an asset, or logical grouping of assets, is determined to be impaired, the asset is written down to its fair value using discounted future cash flows and, if available, quoted market prices.

	Goodwill and other intangible assets – Goodwill and other purchased intangible assets are included in the identifiable assets of the business segment to which they have been assigned. The Company performs impairment tests annually for goodwill, and more often as circumstances require. When it is determined that impairment has occurred, an appropriate charge to earnings is recorded. The Company performed its annual impairment test in the fourth quarters of 2014 and 2013 and determined that the estimated fair values substantially exceeded the carrying values of all the reporting units and accordingly, there was no impairment of goodwill.

	Identifiable intangible assets, other than goodwill, are recorded at cost. Identifiable intangible assets that do not have indefinite lives are amortized on a straight-line basis over their estimated useful lives.



	Deferred income taxes – Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. The effect on deferred tax assets and liabilities of a change in tax laws is recognized in earnings in the period the new laws are enacted. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets unless it is more likely than not that such assets will be realized. Deferred tax liabilities have not been recognized for the undistributed earnings of certain foreign subsidiaries because management intends to permanently reinvest such earnings in foreign operations.

	Self-insured liabilities – The Company is self-insured for property, casualty and workers’ compensation exposures up to various stop-loss coverage amounts. Losses are accrued based upon the Company’s estimates of the liability for the related deductibles of claims incurred. Such estimates utilize actuarial methods based on various assumptions, which include but are not limited to, the Company’s historical loss experience and projected loss development factors. In 2014 and 2013, reversals of self-insured liabilities occurred as a result of favorable loss trends related to self-insured claims.



			2014				2013
	(Dollars in millions)
	Self-insured liabilities at beginning of year		$	8.4			$	7.6
	Expense			2.4				2.5
	Reversal of self-insured liabilities			(0.8	)			(0.4	)
	Cash expenditures			(1.8	)			(1.3	)

	Self-insured liabilities at end of year		$	8.2			$	8.4


	Derivative financial instruments – The Company uses swap contracts to manage copper price risk associated with forecasted purchases of materials used in the Company’s manufacturing processes. The Company uses forward exchange contracts to hedge exposure to currency exchange rate changes on transactions and other commitments denominated in a foreign currency. Contracts are not held for trading or speculative purposes. The Company recognizes the fair value of the swap contracts and forward contracts as an asset or liability at each reporting date. The Company designates the swap contracts as cash flow hedges and the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive (loss) earnings until it is reclassified into earnings when the hedged transaction affects earnings. Gains and losses from hedge ineffectiveness are recognized in current earnings. Because the Company has not elected to designate the forward exchange contracts for hedge accounting treatment, changes in the fair value of the forward exchange contracts are recognized immediately in earnings.

	Asset retirement obligations – Asset retirement obligations are initially recorded at fair value and are capitalized as part of the cost of the related long-lived asset when sufficient information is available to estimate fair value. The capitalized costs are subsequently charged to depreciation expense over the estimated useful life of the related long-lived asset. The fair value of the obligation is determined by calculating the discounted value of expected future cash flows and accretion expense is recorded each month to ultimately increase this obligation to full value.

	The Company recognizes asset retirement obligations for the removal and disposal of residues; dismantling of certain tanks required by governmental authorities; cleaning and dismantling costs for owned rail cars; cleaning costs for leased rail cars and barges; and site demolition.

	The following table describes changes to the Company’s asset retirement obligation liabilities at December 31, 2014 and 2013:



			2014				2013
	(Dollars in millions)
	Asset retirement obligation at beginning of year		$	23.2			$	21.5
	Accretion expense			2.3				1.2
Revision in estimated cash flows			10.3				6.7
Cash expenditures			(4.6	)			(5.6	)
Currency translation			(0.7	)			(0.6	)

Asset retirement obligation at end of year		$	30.5			$	23.2




Litigation and contingencies – Amounts associated with litigation and contingencies are accrued when management, after taking into consideration the facts and circumstances of each matter including any settlement offers, has determined that it is probable that a liability has been incurred and the amount of loss can be reasonably estimated. Legal costs for litigation are expensed as incurred with the exception of legal fees relating the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) sites.

Other current assets – Included in other current assets are prepaid expenses totaling $20.6 million and $17.3 million at December 31, 2014 and 2013, respectively.

Environmental liabilities – The Company accrues for remediation costs and penalties when the responsibility to remediate is probable and the amount of related cost is reasonably estimable. If only a range of potential liability can be estimated and no amount within the range is more probable than another, the accrual is recorded at the low end of that range. Remediation liabilities are discounted if the amount and timing of the cash disbursements are readily determinable.

Deferred revenue from extended product warranty liabilities – The Company defers revenues associated with extended product warranty liabilities based on historical loss experience and sales of extended warranties on certain products. The following table describes changes to the Company’s deferred revenue at December 31, 2014 and 2013:



		2014				2013
(Dollars in millions)
Deferred revenue at beginning of year		$	3.2			$	3.9
Revenue earned			(0.7	)			(0.7	)

Deferred revenue at end of year		$	2.5			$	3.2


Stock-based compensation – The Company records compensation cost over the vesting period for share-based payments to employees at an amount equivalent to the grant date fair value of the stock award. No compensation cost is recognized for any stock awards that are forfeited in the event the recipient fails to meet the vesting requirements.

New_Accounting_Pronouncements

New Accounting Pronouncements	12 Months Ended
New Accounting Pronouncements	Dec. 31, 2014
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	3. New Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 requires an entity to recognize revenue in a manner that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that core principle, the amendment provides five steps that an entity should apply when recognizing revenue. The amendment also specifies the accounting of some costs to obtain or fulfill a contract with a customer and expands the disclosure requirements around contracts with customers. An entity can either adopt this amendment retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying the update recognized at the date of initial application. The amendment is effective for annual reporting periods beginning after December 15, 2016. Early adoption is not permitted. The Company is currently evaluating the impact of the adoption of ASU 2014-09 on the Company’s financial statements.
	In August 2014, the FASB issued ASU No. 2014-15, “Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern” (“ASU 2014-15”), which requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued and provides guidance on determining when and how to disclose going concern uncertainties in the financial statements. Certain disclosures will be required if conditions give rise to substantial doubt about an entity’s ability to continue as a going concern. ASU 2014-15 applies to all entities and is effective for annual and interim reporting periods ending after December 15, 2016, with early adoption permitted. We do not expect that the adoption of this standard will have a material effect on the Company’s financial statements.

Plant_Closures_and_Discontinue

Plant Closures and Discontinued Operations	12 Months Ended
Plant Closures and Discontinued Operations	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Plant Closures and Discontinued Operations	4. Plant Closures and Discontinued Operations

	On January 22, 2014, the Company announced its decision to discontinue coal tar distillation activities at its facility located in Uithoorn, the Netherlands. The decision was made as a result of a detailed analysis of its overall European manufacturing asset footprint in light of deteriorating market conditions in Europe and a variety of other factors, including regulatory requirements for significant capital expenditures at the facility. The Company has discontinued distillation activities and expects to complete closure at the site by the end of 2015. For the year ended December 31, 2014, the Company recorded closure costs of $13.0 million for severance and site demolition liabilities. In the fourth quarter of 2013, the Company recorded an asset impairment charge of $6.9 million related to the facility. The facility is part of the Carbon Materials and Chemicals segment.

	In December 2011, the Company ceased manufacturing operations at its carbon black facility located in Kurnell, Australia. This decision was made as a result of deteriorating business conditions including raw material availability and cost, competition in the export markets due to the strength of the Australian dollar and a variety of other factors. The closure is expected to be completed during 2015. The facility is part of the Carbon Materials and Chemicals segment.

	Details of the restructuring activities and related reserves are as follows:



		Severance			Environmental			Site			Other			Total
		and			remediation			demolition
		employee
		benefits
	(Dollars in millions)
	Reserve at December 31, 2012	$	0.2		$	6.7		$	6.3		$	0.1		$	13.3
	Reversal of accrued charges		(0.1	)		0			(0.3	)		0			(0.4	)
	Cash paid		0			(0.1	)		(2.0	)		(0.1	)		(2.2	)
	Currency translation		0			(1.0	)		(0.7	)		0			(1.7	)

	Reserve at December 31, 2013	$	0.1		$	5.6		$	3.3		$	0		$	9
	Accrual		9.8			0			3.2			0.1			13.1
	Reversal of accrued charges		0			(1.1	)		(0.9	)		0			(2.0	)
	Cash paid		(9.7	)		0			(1.3	)		0			(11.0	)
	Currency translation		(0.2	)		(0.4	)		(0.4	)		0			(1.0	)

	Reserve at December 31, 2014	$	0		$	4.1		$	3.9		$	0.1		$	8.1

Business_Acquisitions

Business Acquisitions	12 Months Ended
Business Acquisitions	Dec. 31, 2014
Business Combinations [Abstract]
Business Acquisitions	5. Business Acquisitions

	Western Poles – On November 19, 2012, the Company acquired the pole distribution business (“Western Poles”) of Ridolfo Forestry Products Pty Limited for cash of $13.8 million and expected future payments totaling $4.9 million (on a discounted basis) to be paid over a period of 36 months assuming certain sales contracts remain in effect. The Western Poles business mainly serves utility customers in Western Australia and complements our existing wood treatment business in Australia. The business is part of the Railroad and Utility Products and Services segment.

	Koppers Ashcroft – On January 20, 2014, the Company acquired the crosstie treating business and related manufacturing facility of Tolko Industries Ltd. located in Ashcroft, British Columbia, Canada. The purchase price was $29.8 million, and was funded primarily by available cash. The allocation of purchase price to acquired assets primarily consisted of inventory totaling $16.0 million, plant and equipment totaling $3.6 million, intangible assets consisting primarily of customer relationships totaling $7.4 million and Canadian tax deductible goodwill of $1.8 million. The goodwill is allocated to the Railroad and Utility Products and Services segment and the customer contracts will be amortized over a period of 12 years.

	Osmose Entities – On August 15, 2014, pursuant to the terms and conditions of a stock purchase agreement, Koppers Inc. acquired Osmose, Inc. and Osmose Railroad Services, Inc. (together, the “Osmose Entities”) from Osmose Holdings, Inc. The aggregate cash purchase price was $494.1 million, net of cash acquired of $27.2 million. The cash purchase price was funded by a new credit agreement with a consortium of banks which provides for a $500 million revolving credit facility and a $300 million term loan. Acquisition-related costs were $5.9 million in 2014 and $0.3 million in 2013 and are reported in selling, general and administrative expenses.

	Subsequent to the acquisition, Osmose, Inc. was renamed Koppers Performance Chemicals Inc. and Osmose Railroad Services, Inc. was renamed Koppers Railroad Structures Inc. Koppers Performance Chemicals Inc.’s wood preservation business develops, manufactures and sells wood preservation chemicals and wood treatment technologies for infrastructure, residential and commercial construction, and agricultural markets. The wood preservation business has operations and sales in North America, South America, Europe, and Australasia. Substantially all of the businesses of Koppers Performance Chemicals Inc. are reported as a new segment, Performance Chemicals. Koppers Railroad Structures Inc. is a provider of railroad infrastructure services, including bridge inspection, engineering, maintenance and repair, and construction services for the Class I and shortline railroads in North America. Koppers Railroad Structures Inc. and one wood treating company are reported as part of the Railroad and Utility Products and Services segment.



	The Osmose Entities had revenues of $391.5 million and net income from continuing operations of $19.3 million for the year ended December 31, 2013. Revenue and operating profit from the Osmose Entities included in our results for the twelve months ended December 31, 2014 totaled $144.3 million and $5.2 million, respectively. Operating profit is net of the amortization of the finished goods inventory value step-up of $3.5 million recognized on the date of acquisition.

	The Company has completed a preliminary valuation analyses to determine the fair values of the Osmose Entities’ assets and liabilities. Accordingly, the financial statements include a preliminary fair value determination based on assumptions and estimates that, while considered reasonable under the circumstances, are subject to changes, which may be material.

	Upon completion of the valuation analyses, there may be additional increases or decreases to the recorded book values of the acquired assets and liabilities, including but not limited to inventories, brands, trademarks, customer relationships and other intangible assets, and property, plant and equipment that could give rise to future amounts of depreciation and amortization expense and changes in related deferred taxes that are not reflected in the financial statements. Accordingly, once the necessary valuation analyses have been performed and the final fair value determination has been completed, actual results may differ materially from the information presented in these financial statements.

	The following table summarizes the Company’s preliminary fair value estimates for the Osmose Entities:



	(Dollars in millions)	Initial
	(Dollars in millions)	Allocation
	Cash and cash equivalents	$	27.2
	Accounts receivable, net		60.3
	Inventories, net		51.9
	Other current assets		3.3
	Property, plant and equipment		57.9
	Goodwill		178.8
	Intangible assets		158.9
	Other assets		10.3

	Total assets acquired		548.6

	Accounts payable		21.2
	Accrued liabilities		18.1
	Other liabilities		15.2

	Total liabilities assumed		54.5

	Net assets acquired	$	494.1


	Goodwill is calculated as the excess of the consideration transferred over the assets acquired and represents the estimated future economic benefits arising from the other assets acquired that could not be individually identified and separately recognized. Goodwill of $175.4 million and $3.4 million has been allocated, on a preliminary basis, to the Performance Chemicals segment and the Railroad and Utility Products and Services segment, respectively. The Company expects that approximately $150 million of the goodwill recognized will be deductible for tax purposes, but this determination is dependent upon the finalization of the purchase price allocation process.



	The following unaudited pro forma information presents a summary of the Company’s revenues and net income from continuing operations as if the acquisition occurred on January 1, 2013. The unaudited pro forma information is not necessarily indicative of operating results that would have been achieved had the acquisition been completed as of January 1, 2013 and does not intend to project the future financial results of the Company after the acquisition of the Osmose Entities. The unaudited pro forma information is based on certain assumptions, which management believes are reasonable, and do not reflect the cost of any integration activities or the benefits from the acquisition and synergies that may be derived from any integration activities.



		Year Ended December 31,
		2014			2013
	(Dollars in millions)
	Revenue	$	1,819.60		$	1,864.10
	(Loss) income from continuing operations attributable to Koppers		(13.0	)		41.5


	Pro forma adjustments reflected in the unaudited pro forma information are based on items that are directly attributable to the acquisition of the Osmose Entities and related financing that are factually supportable and are expected to have a continuing impact on Koppers. These adjustments include, but are not limited to, depreciation and amortization related to fair value adjustments to property, plant and equipment and intangible assets, interest expense on acquisition-related debt, removal of acquisition-related transaction expenses, elimination of finished goods inventory step up, elimination of intercompany sales and related income tax effects of the pro forma adjustments.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	6. Fair Value Measurements

	Carrying amounts and the related estimated fair values of the Company’s financial instruments as of December 31, 2014 and 2013 are as follows:



			December 31, 2014				December 31, 2013
			Fair Value		Carrying		Fair Value		Carrying
			Fair Value		Value		Fair Value		Value
	(Dollars in millions)
	Financial assets:
	Cash and cash equivalents, including restricted cash		$	51.1	$	51.1	$	82.2	$	82.2
	Investments and other assets^(a)			1.5		1.5		1.4		1.4
	Financial liabilities:
	Long-term debt (including current portion)		$	862.1	$	850.5	$	331.2	$	303.1



	(a)	Excludes equity method investments.

	Cash and cash equivalents – The carrying amount approximates fair value because of the short maturity of those instruments.

	Investments and other assets – Represents the broker-quoted cash surrender value on universal life insurance policies. This asset is classified as Level 2 in the valuation hierarchy and is measured from values received from financial institutions.

	Debt – The fair value of the Company’s long-term debt is estimated based on the market prices for the same or similar issues or on the current rates offered to the Company for debt of the same remaining maturities (Level 2). The fair values of the revolving credit facility approximate carrying value due to the variable rate nature of these instruments.

Earnings_per_Common_Share

Earnings per Common Share	12 Months Ended
Earnings per Common Share	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings per Common Share	7. Earnings per Common Share

	The computation of basic earnings per common share for the periods presented is based upon the weighted average number of common shares outstanding during the periods. The computation of diluted earnings per common share includes the effect of nonvested nonqualified stock options and restricted stock units assuming such options and stock units were outstanding common shares at the beginning of the period. The effect of antidilutive securities and performance restricted stock units that have not met vesting criteria are excluded from the computation of diluted earnings per common share.



	The following table sets forth the computation of basic and diluted earnings per common share:



		Year Ended December 31,
		2014			2013			2012
	(Dollars in millions, except share amounts, in thousands, and per share amounts)
	Net (loss) income attributable to Koppers	$	(32.4	)	$	40.4		$	65.6
	Less: discontinued operations		0.6			(0.1	)		(0.1	)

	(Loss) income from continuing operations attributable to Koppers	$	(33.0	)	$	40.5		$	65.7

	Weighted average common shares outstanding:
	Basic		20,463			20,575			20,681
	Effect of dilutive securities		0			240			246

	Diluted		20,463			20,815			20,927

	(Loss) earnings per common share – continuing operations:
	Basic (loss) earnings per common share	$	(1.61	)	$	1.96		$	3.18
	Diluted (loss) earnings per common share		(1.61	)		1.94			3.14

	Other data:
	Antidilutive securities excluded from computation of diluted earnings per common share		362			240			194

Stockbased_Compensation

Stock-based Compensation	12 Months Ended
Stock-based Compensation	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation	8. Stock-based Compensation

	The amended and restated 2005 Long-Term Incentive Plan (the “LTIP”) provides for the grant to eligible persons of stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance awards, dividend equivalents and other stock-based awards, which are collectively referred to as the awards.

	Under the LTIP, the board of directors granted restricted stock units and performance stock units to certain employee participants (collectively, the “stock units”). The restricted stock units vest on the third anniversary of the grant date or ratably over three years, assuming continued employment by the participant. Performance stock units granted generally have three-year performance objectives and all performance stock units have a three-year period for vesting (if the applicable performance objective is obtained). The applicable performance objective is based upon a multi-year cumulative value creation calculation commencing on the first day of each grant year. The number of performance stock units granted represents the target award and participants have the ability to earn between zero and 150 percent of the target award based upon actual performance. If minimum performance criteria are not achieved, no performance stock units will vest.

	Dividends declared on the Company’s common stock during the restriction period of the stock units are credited at equivalent value as additional stock units and become payable as additional common shares upon vesting. In the event of termination of employment, other than retirement, death or disability, any non-vested stock units are forfeited, including additional stock units credited from dividends. In the event of termination of employment due to retirement, death or disability, pro-rata vesting of the stock units over the service period will result for most participants. There are special vesting provisions for the stock units related to a change in control.

	Restricted stock units that vest immediately or have one-year vesting periods are also issued under the LTIP to members of the board of directors in connection with annual director compensation and, from time to time, are issued to members of management in connection with employee compensation.

	Compensation expense for non-vested stock units is recorded over the vesting period based on the fair value at the date of grant. The fair value of stock units is the market price of the underlying common stock on the date of grant.

	The following table shows a summary of the performance stock units as of December 31, 2014:



	Performance Period		Minimum				Target				Maximum
	Performance Period		Shares				Shares				Shares
	2012 – 2014			0				87,039				130,559
	2013 – 2015			0				85,207				127,811
	2014 – 2016			0				102,149				153,224




	The following table shows a summary of the status and activity of non-vested stock awards for the year ended December 31, 2014:



			Restricted				Performance				Total				Weighted Average
			Stock Units				Stock Units				Stock Units				Grant Date Fair
															Value per Unit
	Non-vested at January 1, 2014			148,836				319,984				468,820			$	40.3
	Granted			99,867				108,506				208,373			$	37.92
	Credited from dividends			3,813				8,425				12,238			$	38.52
	Vested			(90,915	)			(132,317	)			(223,232	)		$	40
	Forfeited			(12,695	)			(24,218	)			(36,913	)		$	39.51

	Non-vested at December 31, 2014			148,906				280,380				429,286			$	39.31


	Stock options granted to most executive officers vest and become exercisable upon the completion of a three-year service period which commences on the grant date. The stock options have a term of 10 years. In the event of termination of employment, other than retirement, death or disability, any non-vested options are forfeited for most participants. In the event of termination of employment due to retirement, death or disability, pro-rata vesting of the options over the service period will result for most participants. There are special vesting provisions for the stock options related to a change in control.

	In accordance with accounting standards, compensation expense for non-vested stock options is recorded over the vesting period based on the fair value at the date of grant. The fair value of stock options on the date of grant is calculated using the Black-Scholes-Merton model and the assumptions listed below:



			February 2014 Grant				February 2013 Grant				February 2012 Grant
	Grant date price per share of option award		$	37.93			$	42.76			$	38.21
	Expected dividend yield per share			2.75	%			2.75	%			2.75	%
	Expected life in years			6.5				6.5				6.5
	Expected volatility			52.14	%			53.77	%			55.06	%
	Risk-free interest rate			1.98	%			1.29	%			1.34	%
	Grant date fair value per share of option awards		$	15.26			$	17.28			$	15.82


	The dividend yield is based on the Company’s current and prospective dividend rate which calculates a continuous dividend yield based upon the market price of the underlying common stock. The expected life in years is based on the simplified method permitted under Securities and Exchange Commission Staff Accounting Bulletin No. 14d.2 which calculates the average of the weighted vesting term and the contractual term of the option. This method was selected due to the lack of historical exercise data with respect to the Company. Expected volatility is based on the historical volatility of the Company’s common stock and the historical volatility of certain other similar public companies. The risk-free interest rate is based on U.S. Treasury bill rates for the expected life of the option.

	The following table shows a summary of the status and activity of stock options for the year ended December 31, 2014:



			Options				Weighted Average				Weighted Average				Aggregate Intrinsic
							Exercise Price				Remaining				Value (in millions)
per Option							Contractual Term
							(in years)
Outstanding at December 31, 2013				421,080			$	35.96
Granted				106,658			$	37.93
Exercised			(26,349	)		$	25.51
Expired			(17,870	)		$	40.14
Forfeited			(34,707	)		$	39.75

Outstanding at December 31, 2014			448,812			$	36.58				5.96			$	0.2

Exercisable at December 31, 2014			276,824			$	34.71				4.54			$	0.2


The intrinsic value of stock options exercised in 2014, 2013 and 2012 totaled $0.3 million, $0.0 million and $2.0 million, respectively.



Total stock-based compensation expense recognized and cash received from the exercise of stock options for the three years ended December 31, 2014 is as follows:



		Year Ended December 31,
		2014				2013				2012

(Dollars in millions)
Stock-based compensation expense recognized:
Selling, general and administrative expenses		$	4.7			$	4.3			$	6.9
Less related income tax benefit			1.9				1.7				2.8

Decrease in net income attributable to Koppers		$	2.8			$	2.6			$	4.1

Cash received from the exercise of stock options		$	0.7			$	0.2			$	1.6


As of December 31, 2014 total future compensation expense related to non-vested stock-based compensation arrangements totaled $3.6 million and the weighted-average period over which this expense is expected to be recognized is approximately 21 months.

Segment_Information

Segment Information	12 Months Ended
Segment Information	Dec. 31, 2014
Segment Reporting [Abstract]
Segment Information	9. Segment Information
	The Company has three reportable segments: Carbon Materials and Chemicals, Railroad and Utility Products and Services, and Performance Chemicals. The Company’s reportable segments contain business units that offer different products. The reportable segments are each managed separately because they manufacture and distribute distinct products with different production processes. The business units have been aggregated into three reportable segments since management believes the long-term financial performance of these business units is affected by similar economic conditions.
	The Company’s Carbon Materials and Chemicals segment is primarily a manufacturer of carbon pitch, naphthalene, phthalic anhydride, creosote and carbon black feedstock. Carbon pitch is a critical raw material used in the production of aluminum and for the production of steel in electric arc furnaces. Naphthalene is used for the production of phthalic anhydride and as a surfactant in the production of concrete. Phthalic anhydride is used in the production of plasticizers, polyester resins and alkyd paints. Creosote is used in the treatment of wood and carbon black feedstock is used in the production of carbon black.
	The Company’s Railroad and Utility Products and Services segment sells treated and untreated wood products, manufactured products and services primarily to the railroad and public utility markets. Railroad products include procuring and treating items such as crossties, switch ties and various types of lumber used for railroad bridges and crossings and the manufacture of rail joint bars. Other rail services provided include bridge inspection, engineering, maintenance and repair, and construction services. Railroad services include bridge inspection and engineering services. Utility products include transmission and distribution poles and pilings.
	The Company’s Performance Chemicals segment develops, manufactures, and markets wood preservation chemicals and wood treatment technologies and services a diverse range of end-markets including infrastructure, residential and commercial construction, and agriculture.
	The Company evaluates performance and determines resource allocations based on a number of factors, the primary measure being operating profit or loss from operations. Operating profit does not include equity in earnings of affiliates, other income, interest expense or income taxes. Operating profit also excludes the operating costs of Koppers Holdings Inc., the parent company of Koppers Inc. The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies. Intersegment transactions are eliminated in consolidation.

	The following table sets forth certain sales and operating data, net of all intersegment transactions, for the Company’s segments for the periods indicated:



			Year Ended December 31,
			2014				2013				2012
	(Dollars in millions)
	Revenues from external customers:
	Carbon Materials and Chemicals		$	833.7			$	906.1			$	999.7
	Railroad and Utility Products and Services			597.8				572.2				555.3
	Performance Chemicals			123.5				0				0

	Total		$	1,555.00			$	1,478.30			$	1,555.00

	Intersegment revenues:
	Carbon Materials and Chemicals		$	84.8			$	94.2			$	106.5
	Performance Chemicals			3				0				0

	Total		$	87.8			$	94.2			$	106.5

	Depreciation and amortization^(a):
	Carbon Materials and Chemicals		$	25			$	18.2			$	16.9
	Railroad and Utility Products and Services			11.9				11.5				10.7
	Performance Chemicals			7.1				0				0

	Total		$	44			$	29.7			$	27.6

	Operating profit:
	Carbon Materials and Chemicals		$	(5.3	)		$	43.9			$	83.1
	Railroad and Utility Products and Services			53.6				58.3				45.1
	Performance Chemicals			1.6				0				0
	Corporate^(b)			(16.7	)			(1.9	)			(1.6	)

	Total		$	33.2			$	100.3			$	126.6

	Capital expenditures (including acquisitions):
	Carbon Materials and Chemicals		$	63.7			$	58			$	17.3
	Railroad and Utility Products and Services			44.5				15.9				25
	Performance Chemicals			471.1				0				0
	Corporate			0.7				1.3				0.6

	Total		$	580			$	75.2			$	42.9



	(a)	Excludes impairment charges of $4.7 and $11.9 million in 2014 and 2013, respectively, for Carbon Materials and Chemicals and $0.6 million in 2012 for Railroad and Utility Products and Services.
	(b)	Operating loss for Corporate includes general and administrative costs for Koppers Holdings Inc., the parent company of Koppers Inc., acquisition and acquisition-related integration costs.

	The following table sets forth certain tangible and intangible assets allocated to each of the Company’s segments as of the dates indicated:



			December 31,
			2014				2013
	(Dollars in millions)
	Assets:
	Carbon Materials and Chemicals		$	514.6			$	535.5
Railroad and Utility Products and Services			275.2				179.3
Performance Chemicals			469				0

Segment assets			1,258.80				714.8
Cash and cash equivalents			0				30
Income tax receivable			0				9
Deferred taxes			10				13.3
Deferred financing costs			14.5				7.2
Property, plant and equipment, net			3.9				3.8
Deferred charges			1.6				2.6
Other			5.1				4.2

Total		$	1,293.90			$	784.9

Goodwill:
Carbon Materials and Chemicals		$	65.5			$	68
Railroad and Utility Products and Services			9.3				4.7
Performance Chemicals			172.4				0

Total		$	247.2			$	72.7

Revenues and Long-lived Assets by Geographic Area



		Year				Revenue				Long-lived
		Year				Revenue				assets
(Dollars in millions)
United States			2014			$	833			$	537.1
			2013				782.5				169.1
			2012				827.6				162.9
Australasia			2014				349				160.3
			2013				348.3				100.6
			2012				318.9				72.4
Europe			2014				201.1				47.5
			2013				225.1				32.8
			2012				247.8				36.3
Other countries			2014				171.9				0
			2013				122.4				0
			2012				160.7				0

Total			2014			$	1,555.00			$	744.9
			2013			$	1,478.30			$	302.5
			2012			$	1,555.00			$	271.6

Revenues by geographic area in the above table are attributed by the destination country of the sale. Revenues from non-U.S. countries totaled $722.0 million in 2014, $695.8 million in 2013 and $727.4 million in 2012.

Segment Revenues for Significant Product Lines



		Year Ended December 31,
		2014				2013				2012
(Dollars in millions)
Carbon Materials and Chemicals:
Carbon pitch		$	330.2			$	384.7			$	442.4
Creosote and carbon black feedstock			213.7				228.2				233.8
Phthalic anhydride			91.4				98.6				120
Naphthalene			73.5				64.5				60.3
Other products			124.9				130.1				143.2

			833.7				906.1				999.7
Railroad and Utility Products and Services:
Railroad crossties			342.2				331.1				341.1
Utility poles			96.1				119.3				101.3
Creosote			51.2				61.4				57
Rail joint bars			27.2				24.5				25.6
Railroad infrastructure services			14.8				0				0
Other products			66.3				35.9				30.3

			597.8				572.2				555.3
Performance Chemicals:
Wood preservative products			107				0				0
Other products			16.5				0				0

			123.5				0				0

Total		$	1,555.00			$	1,478.30			$	1,555.00

Income_Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes
	Income Tax Provision
	Components of the Company’s income tax provision from continuing operations are as follows:



			Years Ended December 31,
			2014				2013				2012
	(Dollars in millions)
	Current:
	Federal		$	17.5			$	3.5			$	15.7
	State			0.3				0.6				1.3
	Foreign			14.6				14				8.6

	Total current tax provision			32.4				18.1				25.6
	Deferred:
	Federal			3.1				16.4				4.9
	State			0				2.5				(1.2	)
	Foreign			(1.4	)			(0.2	)			4

	Total deferred tax provision (benefit)			1.7				18.7				7.7

	Total income tax provision		$	34.1			$	36.8			$	33.3

	(Loss) income before income taxes for 2014, 2013 and 2012 included $(1.5) million, $24.6 million and $42.6 million, respectively, from foreign operations.

	The provision for income taxes is reconciled with the federal statutory rate as follows:



			Years Ended December 31,
			2014				2013				2012
	Federal income tax rate			35	%			35	%			35	%
	State income taxes, net of federal tax benefit			(4.8	)			2.1				(0.5	)
	Foreign earnings taxed at different rates			(440.0	)			15.5				0.5
	Domestic production activities deduction			40.8				(2.0	)			(2.7	)
	Deferred tax adjustments			3.2				(0.2	)			(0.3	)
	Change in tax contingency reserves			(15.2	)			(1.5	)			1.2
	Legal entity tax restructuring project			(1,503.2	)			0				0
	Foreign tax credits			1,203.40				(1.1	)			(0.6	)
	Changes to foreign repatriation plans			104				0				0
	Other			(1.2	)			0				0.5

				(578.0	)%			47.8	%			33.1	%

	The Company has not provided any U.S. tax on undistributed earnings of foreign subsidiaries or joint ventures that are reinvested indefinitely. At December 31, 2014 consolidated retained earnings of the Company included approximately $127 million of undistributed earnings, which are permanently invested, from these foreign entities. It is not practical at this time, however, to estimate the amount of taxes that may be payable on the distribution of these earnings.
	Taxes Excluded from Net Income Attributable to Koppers
	The amount of income tax (benefit) included in comprehensive (loss) income but excluded from net income attributable to Koppers relating to adjustments to copper swap contracts is ($2.6) million, $0.0 million, and $0.0 million for the years ended December 31, 2014, 2013, and 2012, respectively.
	The amount of income tax (benefit) provision included in comprehensive (loss) income but excluded from net income attributable to Koppers relating to adjustments to reflect the unfunded status of employee post-retirement benefit plans is $(8.1) million, $13.5 million and $2.2 million for the years ended December 31, 2014, 2013 and 2012, respectively.
	The amount of income tax (expense) benefit included in shareholders’ equity but excluded from net income attributable to Koppers relating to the expense for restricted stock and employee stock options recognized differently for financial and tax reporting purposes was $(0.3) million for the year ended December 31, 2014 and $0.5 million for the year ended December 31, 2013.

	Deferred Tax Assets and Liabilities
	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.
	Significant components of the Company’s deferred tax assets and liabilities are as follows:



			December 31,
			2014				2013
	(Dollars in millions)
	Deferred tax assets:
	Pension and other postretirement benefits obligations		$	19.2			$	10.3
	Tax credits			16.1				10.3
	Net operating loss benefit			14.6				10
Reserves, including insurance, environmental and deferred revenue			12.4				16.5
Asset retirement obligations			7.5				6.8
Accrued employee compensation			6.7				9.4
Book/tax inventory accounting differences			3.6				3.3
Book over tax depreciation and amortization			3.2				1.3
Capital loss benefit			1.1				1.1
Other			6.4				2.2
Valuation allowance			(32.4	)			(19.7	)

Total deferred tax assets			58.4				51.5
Deferred tax liabilities:
Tax over book depreciation and amortization			49				35.4
Unremitted earnings of foreign subsidiaries			0.5				6.8
Tax/book inventory accounting differences			0.2				1.1
Other			0.6				3.7

Total deferred tax liabilities			50.3				47

Net deferred tax assets		$	8.1			$	4.5

A valuation allowance is provided when it is more likely than not that some portion or all of the related deferred tax assets will not be realized. At December 31, 2014, the Company has recorded a valuation allowance of $7.5 million for certain state net operating loss carryforwards and state tax credit carryforwards anticipated to produce no tax benefit. The Company has recorded a valuation allowance of $15.2 million for certain foreign tax credits in the United States expected to produce no benefit. These foreign tax credits will expire in 2024. The Company has recorded a valuation allowance of $8.6 million for foreign net operating losses and certain foreign temporary differences that most likely will not be deducted. Additionally, the Company has recorded a valuation allowance of $1.1 million for certain capital loss carryforwards in Australia and the United Kingdom expected to produce no benefit.
The Company has tax-effected state net operating losses of $9.5 million, which will expire from 2015 to 2034. Additionally, the Company tax-effected foreign net operating losses of $5.1 million, which will begin to expire in 2018.
Uncertain Tax Positions
The Company or one of its subsidiaries files income tax returns in U.S. federal jurisdiction, individual U.S. state jurisdictions and non-U.S. jurisdictions. With few exceptions, the Company is no longer subject to U.S. federal, state and local, or non-U.S. income tax examinations by tax authorities for years before 2008.

As of December 31, 2014 and 2013, the total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate, was approximately $6.0 million and $4.5 million, respectively. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:



		December 31,
		2014				2013				2012
(Dollars in millions)
Balance at beginning of year		$	6.1			$	7.7			$	9.9
Additions based on tax provisions related to the current year			0.6				0.4				0.5
Additions for tax provisions of prior years			0.1				0.4				1.3
Additions as a result of acquisitions			1.6				0				0
Reductions of tax provisions of prior years			(0.6	)			(0.8	)			(0.5	)
Reductions as a result of payments and settlements			0				(1.1	)			(2.8	)
Reductions as a result of a lapse of the applicable statute of limitations			(0.6	)			(0.5	)			(0.7	)

Balance at end of year		$	7.2			$	6.1			$	7.7

The Company recognizes interest expense or interest income and any related penalties from uncertain tax positions in income tax expense. For each year ended December 31, 2014, 2013 and 2012, the Company recognized $1.5 million, $(0.1) million and $0.3 million, respectively, in interest and penalties. As of December 31, 2014 and 2013, the Company had accrued approximately $2.7 million and $1.2 million for interest and penalties, respectively.

Inventories

Inventories	12 Months Ended
Inventories	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventories	11. Inventories

	Inventories as of December 31, 2014 and 2013 were as follows:



		December 31,
		2014		2013
	(Dollars in millions)
	Raw materials	$	191.1	$	105.4
	Work in process		2.6		19.2
	Finished goods		103.6		94.8

			297.3		219.4
	Less revaluation to LIFO		56.1		50.6

	Net	$	241.2	$	168.8


	For the year ended December 31, 2013, liquidations of LIFO inventories increased operating profit by $0.2 million.

Equity_Investments

Equity Investments	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments	12. Equity Investments
	The Company holds two investments in unconsolidated companies. KSA Limited Partnership is a 50 percent owned concrete crosstie operation located in Portsmouth, Ohio. Tangshan Koppers Kailuan Carbon Chemical Company Limited (“TKK”) is a 30 percent owned tar distillation facility in the Hebei Province of China. No dividends were paid for the three years ended December 31, 2014. Equity in (losses) earnings for the three years ended December 31, 2014 were as follows:


		Equity
		(loss) income
	(Dollars in millions)
	2014	$	(1.6	)
	2013		0.8
	2012		0.8

Property_Plant_and_Equipment

Property, Plant and Equipment	12 Months Ended
Property, Plant and Equipment	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	13. Property, Plant and Equipment

	Property, plant and equipment as of December 31, 2014 and 2013 were as follows:



		December 31,
		2014		2013
	(Dollars in millions)
	Land	$	18.7	$	9.1
	Buildings		45.3		30.6
	Machinery and equipment		678.6		608.1

			742.6		647.8
	Less accumulated depreciation		442.9		450.8

	Net	$	299.7	$	197


	Depreciation expense, including impairment charges, for the years ended December 31, 2014, 2013 and 2012 amounted to $38.8 million, $38.3 million and $25.2 million, respectively.

	Impairments – Impairment charges for 2014, 2013 and 2012 were $4.7 million, $11.9 million and $0.6 million, respectively. In 2014, impairment charges primarily related to the Carbon Material and Chemicals’ plant in Tangshan, China ($2.8 million, net of non-controlling interest). These impairment charges were calculated using a probability-weighted discounted cash flow model.

	The impairment of the Company’s 60-percent owned plant in Tangshan, China is due to the forced closure of a neighboring metallurgical coke facility. In October 2013, the Company was informed by the Tangshan Municipal People’s Government (“Tangshan Government”) of its intention to close the two coke batteries owned and operated by the Tangshan Iron and Steel Group Co., Ltd (“TISCO”) in Tangshan, China. The Tangshan Government has ordered the closure of these coke batteries in an effort to improve the air quality in the Tangshan area. One TISCO coke battery closed in March 2014 and the Company has been informed that the remaining TISCO coke battery will cease production sometime within the next twelve to eighteen months.

	The Company’s 60-percent owned subsidiary, Koppers (China) Carbon & Chemical Company Limited (“KCCC”) is located near to TISCO’s coke facility and relies on its operations for a significant portion of raw material supply, utilities and other shared services. Closure of the TISCO coke batteries directly impacts KCCC’s ability to operate its coal tar distillation plant and the Company has determined that it is unable to continue coal tar distillation activities at the site once TISCO ceases production activities at the adjacent facility. As of December 31, 2014, all fixed assets directly related to the facility have been substantially depreciated.

	The Company believes it would be able to continue fulfilling current domestic Chinese customers and its export commitments with capacity at Koppers (Jiangsu) Carbon Chemical Company Limited, which commenced production in August 2014, its other 30 percent owned Chinese company and through other commercial relationships in China. However, the Company’s margin on export sales may be negatively affected as a result of these actions.



	The 2013 impairment of the Company’s plant in the Netherlands was due to the decision to discontinue coal tar distillation activities at the Uithoorn plant in July 2014. A final determination to discontinue production was made in January 2014 after consultation with and agreement on a severance plan with the plant’s works council and trade union, respectively. As of December 31, 2014, all fixed assets directly related to the facility have been substantially depreciated.

	The impairment charge in 2012 related to a Railroad and Utility Products and Services segment’s electricity co-generation plant in the United States.

	Port of Portland – In February 2012, approximately 400 tons of carbon pitch leaked from a storage tank at the Company’s terminal facility in Portland, Victoria, Australia. All of the coal tar pitch was contained within the tank farm area and was recovered. Insurance recoveries associated with the leak were a net $0.1 million and $1.2 million for the years ended December 31, 2014 and 2013, respectively. Costs directly associated with the leak were $2.5 million for the year ended December 31, 2012 and include inventory losses, emergency response expenses, incremental logistics costs, and material clean-up and removal expenses, net of insurance recoveries.

Goodwill_and_Other_Identifiabl

Goodwill and Other Identifiable Intangible Assets	12 Months Ended
Goodwill and Other Identifiable Intangible Assets	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Identifiable Intangible Assets	14. Goodwill and Other Identifiable Intangible Assets

	The change in the carrying amount of goodwill attributable to each business segment for the years ended December 31, 2014 and December 31, 2013 was as follows:



		Carbon Materials and			Railroad and			Performance			Total
		Chemicals			Utility Products			Chemicals
					and Services
	(Dollars in millions)
	Balance at December 31, 2012	$	70.2		$	5.4		$	0		$	75.6
	Currency translation		(2.2	)		(0.7	)		(0.0	)		(2.9	)

	Balance at December 31, 2013	$	68		$	4.7		$	0		$	72.7
	Acquisitions		0			5.2			175.4			180.6
	Currency translation		(2.5	)		(0.6	)		(3.0	)		(6.1	)

	Balance at December 31, 2014	$	65.5		$	9.3		$	172.4		$	247.2


	The Company’s identifiable intangible assets with finite lives are being amortized over their estimated useful lives and are summarized below:



								December 31,
								2014								2013
		Estimated			Weighted			Gross			Accumulated			Net		Gross		Accumulated		Net
		life in years			average			Carrying			Amortization					Carrying		Amortization
					remaining life in			Amount								Amount
					years

	(Dollars in millions)
	Customer contracts		9 to 17			14.8		$	149.9		$	14.5		$	135.4	$	19.8	$	9.7	$	10.1
	Technology		4 to 12			7			26.7			1.4			25.3		0		0		0
	Trademarks		4 to 7			6.5			5.6			0.3			5.3		0		0		0
	Supply contracts		10			5.2			2.6			1.2			1.4		2.9		1.1		1.8
	Non-compete agreements		12			9.8			1.5			1.2			0.3		1.6		1.3		0.3
	Favorable lease agreements		3			0			0.8			0.8			0		0.8		0.8		0

	Total					13.2		$	187.1		$	19.4		$	167.7	$	25.1	$	12.9	$	12.2




	Acquired intangible assets for the year ended December 31, 2014 totaled $133.8 million for customer relationships, $26.9 million for technology and $5.6 million for trademarks. In 2014, the gross carrying value of identifiable intangible assets decreased by $2.2 million due to foreign currency translation. Total amortization expense related to these identifiable intangible assets was $8.4 million, $2.1 million and $1.9 million for the years ended December 31, 2014, 2013 and 2012, respectively. Estimated amortization expense for the next five years is summarized below:



		Estimated
		annual
		amortization
	(Dollars in millions)
	2015		14.9
	2016		14.5
	2017		14.3
	2018		14.3
	2019		14.2

Pensions_and_Postretirement_Be

Pensions and Post-retirement Benefit Plans	12 Months Ended
Pensions and Post-retirement Benefit Plans	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Pensions and Post-retirement Benefit Plans	15. Pensions and Post-retirement Benefit Plans

	The Company and its subsidiaries maintain a number of defined benefit and defined contribution plans to provide retirement benefits for employees in the U.S., as well as employees outside the U.S. These plans are maintained and contributions are made in accordance with the Employee Retirement Income Security Act of 1974, local statutory law or as determined by the board of directors. The defined benefit pension plans generally provide benefits based upon years of service and compensation. Pension plans are funded except for three domestic non-qualified defined benefit pension plans for certain key executives.

	In the U.S., all qualified defined benefit pension plans for salaried employees have been closed to new participants and a number of plans, including most plans for hourly employees, have been frozen or are scheduled to be frozen in the next year. Accordingly, these pension plans no longer accrue additional years of service or recognize future increases in compensation for benefit purposes. In addition, a number of pension plans are subject to a “soft” freeze which precludes new employees from entering the defined benefit pension plans.

	The defined contribution plans generally provide retirement assets to employee participants based upon employer and employee contributions to the participant’s individual investment account. The Company also provides retiree medical insurance coverage to certain U.S. employees and a life insurance benefit to most U.S. employees. For salaried employees, the retiree medical and retiree insurance plans have been closed to new participants.

	Expense related to defined contribution plans totaled $6.9 million, $5.3 million and $4.7 million for the years ended December 31, 2014, 2013 and 2012, respectively. Expense related to contributions to multi-employer pension plans totaled $0.2 million, $0.4 million and $0.4 million for the years ended December 31, 2014, 2013 and 2012, respectively.

	Net periodic pension costs for 2014, 2013 and 2012 were as follows:



			December 31,
			Pension Benefits												Other Benefits
			2014				2013				2012				2014			2013			2012
	(Dollars in millions)
	Components of net periodic benefit cost:
	Service cost		$	2.7			$	3.4			$	3.5			$	0.1		$	0.1		$	0.1
	Interest cost			11.8				10.7				10.7				0.5			0.5			0.5
	Expected return on plan assets			(13.9	)			(12.5	)			(10.7	)			0			0			0
	Amortization of prior service cost			(0.2	)			0.1				0.1				0			0			0
	Amortization of net loss			4				7.6				8.1				0.2			(0.1	)		0
	Amortization of transition asset			0				0				(0.3	)			0			0			0
	Settlements and curtailments			0				0.1				0.3				0			0			0

	Net periodic benefit cost		$	4.4			$	9.4			$	11.7			$	0.4		$	0.5		$	0.6




	Net periodic pension (credit) cost that is expected to be recognized from the amortization of prior service cost and net loss is estimated to total $(0.3) million and $6.3 million, respectively, for all plans in 2015.

	The change in the funded status of the pension and postretirement plans as of December 31, 2014 and December 31, 2013 is as follows:



			December 31,
			Pension Benefits								Other Benefits
			2014				2013				2014				2013
	(Dollars in millions)
	Change in benefit obligation:
	Benefit obligation at beginning of year		$	237.8			$	255.2			$	10.4			$	11.2
	Service cost			2.7				3.4				0.1				0.1
	Interest cost			11.8				10.7				0.5				0.5
	Plan participants’ contributions			0.2				0.2				0				0
	Actuarial losses (gains)			39.4				(18.6	)			(1.1	)			(1.3	)
	Plan amendments			0				(1.5	)			0				0
	Settlements			0				(0.9	)			0				0
	Currency translation			(4.4	)			0.2				0				0
	Benefits paid			(11.8	)			(10.9	)			(0.1	)			(0.1	)

	Benefit obligation at end of year			275.7				237.8				9.8				10.4
	Change in plan assets:
	Fair value of plan assets at beginning of year			205.7				175.6				0				0
	Actual return on plan assets			24				19.2				0				0
	Employer contribution			15.1				22.5				0.1				0.1
	Plan participants’ contributions			0.2				0.2				0				0
	Settlements			0				(0.9	)			0				0
	Currency translation			(3.7	)			0				0				0
	Benefits paid			(11.8	)			(10.9	)			(0.1	)			(0.1	)

	Fair value of plan assets at end of year			229.5				205.7				0				0

Funded status of the plan		$	(46.2	)		$	(32.1	)		$	(9.8	)		$	(10.4	)

Amounts recognized in the balance sheet consist of:
Noncurrent assets		$	0.2			$	0.6			$	0			$	0
Current liabilities			0.9				0.7				0.7				0.8
Noncurrent liabilities			45.5				32				9.1				9.6
Pension plans with benefit obligations in excess of plan assets:
Benefit obligation		$	237			$	231.9
Fair value of plan assets			200.2				199.2
Pension plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligation		$	230.7			$	225
Fair value of plan assets			200.2				199.2


The measurement date for all pension and postretirement assets and obligations is December 31 for each respective year.

The accumulated benefit obligation for all defined benefit pension plans as of December 31, 2014 and 2013 was $269.0 million and $230.6 million, respectively.



Expected Contributions for the 2015 Fiscal Year

The expected contributions by the Company for 2015 are estimated to be $3.1 million for pension plans and $0.7 million for other benefit plans.

Projected Benefit Payments

Benefit payments for pension benefits, which are primarily funded by the pension plan assets, and other benefits, which are funded by general corporate assets and reflecting future expected service as appropriate, are expected to be paid as follows:



		Pension Benefits				Other Benefits
(Dollars in millions)
2015		$	12.1			$	0.7
2016			12.4				0.7
2017			13.3				0.7
2018			14.3				0.7
2019			13.8				0.8
2020 – 2024			78.9				3.1


Weighted-Average Assumptions as of December 31

		December 31,
		Pension Benefits								Other Benefits
		2014				2013				2014				2013
Discount rate			4.12	%			5.06	%			4.32	%			5.25	%
Expected return on plan assets			6.31				7.04
Rate of compensation increase			4				3.13
Initial medical trend rate											6.95				7.15


Basis for the Selection of the Long-Term Rate of Return on Assets

The long-term rate of return on assets assumption was determined by using the plan’s asset allocation as described in the plan’s investment policy and modeling a distribution of compound average returns over a time horizon. The model uses asset class return, variance, and correlation assumptions to produce the expected return. The return assumptions used forward looking gross returns influenced by the current bond yields, corporate bond spreads and equity risk premiums based on current market conditions.

In general, the long-term rate of return is the sum of the portion of total assets in each asset class multiplied by the expected return for that class, adjusted for expected expenses to be paid from the assets. To develop the expected long-term rate of return on assets assumption, the Company considered the historical returns and the future expectations for returns for each asset class, as well as the target asset allocation of the pension portfolio.

Investment Strategy

The weighted average asset allocation for the Company’s pension plans at December 31 by asset category is as follows:

		December 31,
		2014				2013
Debt securities			71	%			59	%
Equity securities			26				38
Other			3				3

			100	%			100	%


The Company’s investment strategy for its pension plans is to maintain an adequate level of diversification, to reduce interest rate and market risk and to provide adequate liquidity to meet immediate and future benefit payment requirements. The Company’s overall investment strategy is to achieve a mix of growth seeking assets, principally U.S. and international public company equity securities and income generating assets, principally debt securities, real estate and cash. Currently, the Company targets an allocation of 30 percent to 40 percent growth seeking assets and 60 percent to 70 percent income generating assets on an overall basis. The Company utilizes investment managers to assist in identifying and monitoring investments that meet these allocation criteria. With respect to the largest pension plan, the Company has implemented a strategy of reallocating pension assets from growth seeking assets to income generating assets as certain funded status levels are reached.

The investment valuation policy of the Company is to value investments at fair value. Most of the assets are invested in pooled or commingled investment vehicles. The Company’s interest in these investment vehicles is expressed as a unit of account with a value per unit that is the result of the accumulated values of the underlying investments. Equity securities held within these investment vehicles are typically priced on a daily basis using the closing market price from the exchange the security is traded. Debt securities held within these investment vehicles are typically priced on a daily basis by independent pricing services. The fair value of real estate investments are either priced through a listing on an exchange or are subject to periodic appraisals.

The pension assets are all substantially held in pooled or commingled investment vehicles. The following table sets forth by level, the Company’s pension plan assets at fair value, within the fair value hierarchy, as of December 31, 2014 and December 31, 2013:

		As of December 31, 2014
		Quoted prices				Significant				Significant				Total
		in active				observable				unobservable
		markets for				inputs				inputs
		identical assets				(Level 2)				(Level 3)
		(Level 1)
(Dollars in millions)
U.S. equity securities		$	17.5			$	10.5			$	0				$ 28.0
International equity securities			12.7				20				0				32.7
U.S. debt securities			36.4				92.1				0				128.5
International debt securities			7.8				26.8				0				34.6
Real estate and other investments			0				1.9				0				1.9
Cash and cash equivalents			0				3.8				0				3.8

		$	74.4			$	155.1			$	0				$229.50


		As of December 31, 2013
		Quoted prices				Significant				Significant				Total
		in active				observable				unobservable
		markets for				inputs				inputs
		identical assets				(Level 2)				(Level 3)
		(Level 1)
(Dollars in millions)
U.S. equity securities		$	17.8			$	15.9			$	0				$ 33.7
International equity securities			0				44.3				0				44.3
U.S. debt securities			24.8				64.7				0				89.5
International debt securities			7.4				24.9				0				32.3
Real estate and other investments			0				1.5				0				1.5
Cash and cash equivalents			0				4.4				0				4.4

		$	50			$	155.7			$	0				$205.70




Health Care Cost Trend Rates

The 2014 initial health care cost trend rate is assumed to be 7.15 percent and is assumed to decrease gradually to 4.5 percent in 2027 and remain at that level thereafter. The assumed health care cost trend rate has a significant effect on the amounts reported for other postretirement benefit liability. A one-percentage-point change in the assumed health care cost trend rate would have the following effects:



		1% Increase				1% Decrease
(Dollars in millions)
Increase (decrease) from change in health care cost trend rates:
Postretirement benefit expense		$	0			$	0
Postretirement benefit liability			0.2				(0.2	)


Incentive Plan

The Company has short-term management incentive plans that pay cash bonuses if certain Company performance and individual goals are met. The charge to operating expense for these plans was $3.8 million in 2014, $2.3 million in 2013 and $5.2 million in 2012.

Debt

Debt	12 Months Ended
Debt	Dec. 31, 2014
Debt Disclosure [Abstract]
Debt	16. Debt
	Debt at December 31, 2014 and December 31, 2013 was as follows:


							December 31,
		Weighted			Maturity		2014		2013
		Average
		Interest Rate
	(Dollars in millions, except interest rates)
	Term Loan		3.63%			2019	$	292.5	$	0
	Revolving credit facility		3.63%			2019		204.5	$	0
	Construction and other loans		5.81%			2018		56.5		6.6
	Senior Notes		7⁷/ ⁸%			2019		297		296.5

	Total debt							850.5		303.1
	Less short-term debt and current maturities of long-term debt							43.9		0

	Long-term debt (excluding current portion)						$	806.6	$	303.1

	Revolving Credit Facility
	On August 15, 2014, Koppers Inc. replaced its $350.0 million revolving credit facility with a new $500.0 senior secured revolving credit facility and a $300.0 million senior secured term loan to finance its acquisition of the Osmose Entities (the “Senior Secured Credit Facilities”). Both borrowings mature on August 15, 2019. The interest rates on the new borrowings are variable and are based on LIBOR. The initial interest rate on the borrowings at August 15, 2014 was 3.25 percent. The senior secured term loan has quarterly principal repayment obligations of 2.5 percent of the original principal amount borrowed, or $7.5 million.
	Borrowings under the revolving credit facility and term loan are secured by a first priority lien on substantially all of the assets of Koppers Inc. and its material domestic subsidiaries. The revolving credit facility and term loan contain certain covenants for Koppers Inc. and its restricted subsidiaries that limit capital expenditures, additional indebtedness, liens, dividends, investments or acquisitions. In addition, such covenants give rise to events of default upon the failure by Koppers Inc. and its restricted subsidiaries to meet certain financial ratios.
	As of December 31, 2014, the Company had $233.4 million of unused revolving credit availability for working capital purposes after restrictions from certain letter of credit commitments and other covenants. As of December 31, 2014, $61.5 million of commitments were utilized by outstanding letters of credit.

	Construction Loans
	On November 18, 2013, the Company’s 75-percent owned subsidiary, Koppers (Jiangsu) Carbon Chemical Company Limited (“KJCC”) entered into two committed loan facility agreements for a combined commitment of RMB 265 million or approximately $44 million. The third party bank provided facility has a commitment amount of RMB 198.8 million and the other committed facility of RMB 66.2 million is provided by the 25-percent non-controlling shareholder in KJCC. Borrowings under the third party bank facility are secured by a letter of credit issued by a bank under the Koppers Inc. revolving credit facility. The committed facilities were used to finance the costs related to the construction of the coal tar distillation plant in Pizhou, Jiangsu province in China. The facilities are variable rate and have certain financial covenants that monitor minimum net worth and leverage. KJCC will repay the loans in six installments every six months starting in May 2016 with a final repayment on November 18, 2018, the maturity date of the loans.
	Senior Notes
	The Koppers Inc. 7⁷/₈ percent Senior Notes due 2019 (the “Senior Notes”) were issued on December 1, 2009 at an offering price of 98.311 percent of face value, or $294.9 million and have a principal amount at maturity of $300.0 million. The Senior Notes have an effective interest rate yield of 8¹/₈ percent per annum. The 2009 Senior Notes are our senior obligations, are fully and unconditionally guaranteed by KH and certain of our wholly-owned domestic subsidiaries, and, as of August 15, 2014, are secured equally and ratably with the obligations under our Senior Secured Credit Facilities.
	Interest on the Senior Notes is payable semiannually on December 1 and June 1 each year. On or after December 1, 2014, the Company is entitled to redeem all or a portion of the Senior Notes at a redemption price of 103.938 percent of principal value, declining annually in ratable amounts until the redemption price is equivalent to the principal value on December 1, 2017.
	The indenture governing the Senior Notes includes customary covenants that restrict, among other things, the ability of Koppers Inc. and its restricted subsidiaries to incur additional debt, pay dividends or make certain other restricted payments, incur liens, merge or sell all or substantially all of the assets of Koppers Inc. or its subsidiaries or enter into various transactions with affiliates.
	Debt Maturities and Deferred Financing Costs
	At December 31, 2014 the aggregate debt maturities for the next five years are as follows:


	(Dollars in millions)
	2015	$	43.9
	2016		36.4
	2017		44.9
	2018		51.3
	2019		677
	Thereafter		0

	Total maturities		853.5
	Future accretion on Senior Notes		(3.0	)

	Total debt	$	850.5

	Unamortized deferred financing costs (net of accumulated amortization of $0.8 million and $5.9 million at December 31, 2014 and 2013, respectively) were $10.3 million and $7.2 million at December 31, 2014 and 2013, respectively, and are included in other assets.

Leases

Leases	12 Months Ended
Leases	Dec. 31, 2014
Leases [Abstract]
Leases	17. Leases

	Future minimum commitments for operating leases having non-cancelable lease terms in excess of one year are as follows:



	(Dollars in millions)
	2015	$	35.6
	2016		30.5
	2017		27.5
	2018		21.2
	2019		7.6
	Thereafter		33.7

	Total	$	156.1


	Operating lease expense for 2014, 2013 and 2012 was $36.7 million, $39.4 million and $44.3 million, respectively.

Derivative_Financial_Instrumen

Derivative Financial Instruments	12 Months Ended
Derivative Financial Instruments	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	18. Derivative Financial Instruments

	The Company utilizes derivative instruments to manage exposures to risks that have been identified and measured and are capable of being controlled. The primary risks managed by the company by using derivative instruments are commodity price risk associated with copper and foreign currency exchange risk associated with a number of currencies, principally the U.S. dollar, the Canadian dollar, the Euro and British pounds. Swap contracts on copper are used to manage the price risk associated with forecasted purchases of materials used in the Company’s manufacturing processes. Generally, the Company will not hedge cash flow exposures for durations longer than 30 months. The Company enters into foreign currency forward contracts to manage foreign currency risk associated with the Company’s receivable and payable balances. Generally, the Company enters into master netting arrangements with the counterparties and offsets net derivative positions with the same counterparties. Currently, the Company’s agreements do not require cash collateral.

	ASC Topic 815-10, “Derivatives and Hedging,” requires companies to recognize all derivative instruments as either assets or liabilities at fair value in the balance sheet. Derivative instruments’ fair value is determined using significant other observable inputs, or Level 2 in the fair value hierarchy. In accordance with ASC Topic 815-10, the Company designates commodity swaps as cash flow hedges of forecasted purchases of commodities. For derivative instruments that are designated and qualify as cash flow hedges, the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive (loss) income and is reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Gains and losses on the derivative instruments representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current earnings.

	As of December 31, 2014, the Company has outstanding copper swap contracts totaling 19.6 million pounds and the fair value of these swap contracts was $(6.5) million which is classified in accrued liabilities in the consolidated balance sheet. The amount of loss recognized in other comprehensive loss totaled $3.8 million, net of tax, at December 31, 2014. The ineffective portion of the copper swap contracts totaled $0.1 million and was charged to cost of sales for the year ended December 31, 2014. In the next twelve months the Company estimates that $2.8 million of unrealized losses, net of tax, related to commodity price hedging will be reclassified from other comprehensive loss into earnings.

	Forward contracts related to foreign currency are not designated as hedges and fair value changes in these contracts are immediately charged to earnings and are classified in other income in the condensed consolidated statement of income. As of December 31, 2014, the Company has outstanding foreign currency forward contracts with a net fair value totaling $0.0 million, consisting of a gross derivative asset of $0.2 million and a gross derivative liability of $0.2 million. The currency units outstanding at December 31, 2014 were British Pound of GBP 15.6 million, Canadian Dollar of CAD 8.0 million and United States Dollar of USD 7.6 million.

Common_Stock_and_Senior_Conver

Common Stock and Senior Convertible Preferred Stock	12 Months Ended
Common Stock and Senior Convertible Preferred Stock	Dec. 31, 2014
Text Block [Abstract]
Common Stock and Senior Convertible Preferred Stock	19. Common Stock and Senior Convertible Preferred Stock
	Changes in senior convertible preferred stock, common stock and treasury stock for the three years ended December 31, 2014 are as follows:

		Year Ended December 31,
		2014			2013			2012
	(Shares in thousands)
	Senior Convertible Preferred Stock:
	Balance at beginning and end of year		0			0			0

	Common Stock:
	Balance at beginning of year		21,722			21,585			21,309
	Issued for employee stock plans		216			137			276

	Balance at end of year		21,938			21,722			21,585

	Treasury Stock:
	Balance at beginning of year		(1,390	)		(951	)		(706	)
	Shares repurchased		(53	)		(439	)		(245	)

	Balance at end of year		(1,443	)		(1,390	)		(951	)

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	20. Commitments and Contingent Liabilities

	The Company and its subsidiaries are involved in litigation and various proceedings relating to environmental laws and regulations and toxic tort, product liability and other matters. Certain of these matters are discussed below. The ultimate resolution of these contingencies is subject to significant uncertainty and should the Company or its subsidiaries fail to prevail in any of these legal matters or should several of these legal matters be resolved against the Company or its subsidiaries in the same reporting period, these legal matters could, individually or in the aggregate, be material to the consolidated financial statements.

	Legal Proceedings

	Coal Tar Pitch Cases. Koppers Inc., along with other defendants, is currently a defendant in lawsuits filed in two states in which the plaintiffs claim they suffered a variety of illnesses (including cancer) as a result of exposure to coal tar pitch sold by the defendants. There are approximately 112 plaintiffs in 60 cases pending as of December 31, 2014 as compared to 111 plaintiffs in 61 cases pending as of December 31, 2013. As of December 31, 2014, there are a total of 59 cases pending in state court in Pennsylvania, and one case pending in state court in Tennessee. Koppers Inc. has been dismissed from three cases formerly pending in state court in Arkansas.

	The plaintiffs in all 60 pending cases seek to recover compensatory damages, while plaintiffs in 55 cases also seek to recover punitive damages. The plaintiffs in the 59 cases filed in Pennsylvania state court seek unspecified damages in excess of the court’s minimum jurisdictional limit. The plaintiffs in the Tennessee state court case each seek damages of $15.0 million. The other defendants in these lawsuits vary from case to case and include companies such as Beazer East, Inc., United States Steel Corporation, Honeywell International Inc., Vertellus Specialties Inc., Dow Chemical Company, UCAR Carbon Company, Inc., Exxon Mobil Corporation, SGL Carbon Corporation and Alcoa, Inc. Discovery is proceeding in these cases. No trial dates have been set in any of these cases.

	The Company has not provided a reserve for these lawsuits because, at this time, the Company cannot reasonably determine the probability of a loss, and the amount of loss, if any, cannot be reasonably estimated. The timing of resolution of these cases cannot be reasonably determined. Although Koppers Inc. is vigorously defending these cases, an unfavorable resolution of these matters may have a material adverse effect on the Company’s business, financial condition, cash flows and results of operations.

	Gainesville. Koppers Inc. operated a utility pole treatment plant in Gainesville from December 29, 1988 until its closure in 2009. The property upon which the utility pole treatment plant was located was sold by Koppers Inc. to Beazer East, Inc. in 2010.



	In November 2010, a class action complaint was filed in the Circuit Court of the Eighth Judicial Circuit located in Alachua County, Florida by residential real property owners located in a neighborhood west of and immediately adjacent to the former utility pole treatment plant in Gainesville. The complaint named Koppers Holdings Inc., Koppers Inc., Beazer East and several other parties as defendants. In a second amended complaint, plaintiffs define the putative class as consisting of all persons who are present record owners of residential real properties located in an area within a two-mile radius of the former Gainesville wood treating plant. Plaintiffs further allege that chemicals and contaminants from the Gainesville plant have contaminated real properties within the two mile geographical area, have caused property damage (diminution in value) and have placed residents and owners of the putative class properties at an elevated risk of exposure to and injury from the chemicals at issue. The second amended complaint seeks damages for diminution in property values, the establishment of a medical monitoring fund and punitive damages.

	The case was removed to the United States District Court for the Northern District of Florida in December 2010. The district court dismissed Koppers Holdings Inc. in September 2013 on the ground that there was no personal jurisdiction. Plaintiffs’ appeal of the dismissal of Koppers Holdings Inc. was dismissed in December 2013. Under the current scheduling order, the Court has set a deadline of February 23, 2015 for completion of class factual discovery with expert witness discovery to follow. Discovery on the merits is stayed until further order of the court.

	The Company has not provided a reserve for this matter because, at this time, it cannot reasonably determine the probability of a loss, and the amount of loss, if any, cannot be reasonably estimated. The timing of resolution of this case cannot be reasonably determined. Although the Company is vigorously defending this case, an unfavorable resolution of this matter may have a material adverse effect on the Company’s business, financial condition, cash flows and results of operations.

	Virgin Islands. Koppers Performance Chemicals Inc. (“KPC”) is currently a defendant in a putative class action lawsuit filed in the United States District Court of the Virgin Islands. The plaintiffs claim, on behalf of themselves and others similarly situated, that KPC’s wood preservative products and formulas are defective, and the complaint alleges the following causes of action: breach of contract, negligence, strict liability, fraud and violation of Virgin Islands Consumer Fraud and Deceptive Business Practices statute. The putative class is defined as all users (residential or commercial) of wood products treated with KPC wood preserving products in the United States who purchased such wood products from January 1, 2004 to the present. Alternatively, plaintiffs allege that the putative class should be all persons and entities that have owned or acquired buildings or other structures physically located in the U.S. Virgin Islands that contain wood products treated with KPC wood preserving products from January 1, 2004 to the present. The complaint alleges plaintiffs are entitled to unspecified “economic and compensatory damages”, punitive damages, costs and disgorgement of profits. The complaint further requests a declaratory judgment and injunction to establish an inspection and disposal program for class members’ structures. The lawsuit was filed on July 16, 2014, and KPC has filed a motion to dismiss. Plaintiffs have responded to the motion and KPC has filed a reply. The motion has been fully briefed and we are awaiting a ruling by the court. The Company has not provided a reserve for this matter because, at this time, it cannot reasonably determine the probability of a loss, and the amount of loss, if any, cannot be reasonably estimated. The timing of resolution of this case cannot be reasonably determined.

	Other Matters. In July 2012, Koppers Netherlands B.V.’s (“Koppers Netherlands”) coal tar distillation plant suffered a series of electrical disruptions which significantly affected plant operations and prevented the resumption of plant operations for a period of approximately three weeks. As a result of the suspension of operations, the coal tar distillation plant was unable to provide steam and other services to an adjacent unaffiliated plant. This unaffiliated plant and Koppers Netherlands’ plant share certain services and plant infrastructure under a cost sharing agreement. In September 2012, Koppers Netherlands received a business interruption claim from the owner of the unaffiliated plant that included an initial claim for lost profits of approximately $1.7 million. In July 2013 the owner of the unaffiliated plant filed a request for arbitration with the Netherlands Arbitration Institute seeking damages for the business interruption claim plus interest, costs and legal fees. In its statement of claim to the arbitration board, the owner of the unaffiliated facility has claimed damages of at least $3.1 million for these costs. The arbitration hearing was held in June 2014. This matter was settled on January 19, 2015 for $1.4 million, which amount will be paid by the insurance carrier for Koppers Netherlands.



	Environmental and Other Litigation Matters

	The Company and its subsidiaries are subject to federal, state, local and foreign laws and regulations and potential liabilities relating to the protection of the environment and human health and safety including, among other things, the cleanup of contaminated sites, the treatment, storage and disposal of wastes, the discharge of effluent into waterways, the emission of substances into the air and various health and safety matters. The Company’s subsidiaries expect to incur substantial costs for ongoing compliance with such laws and regulations. The Company’s subsidiaries may also face governmental or third-party claims, or otherwise incur costs, relating to cleanup of, or for injuries resulting from, contamination at sites associated with past and present operations. The Company accrues for environmental liabilities when a determination can be made that a liability is probable and reasonably estimable.

	Environmental and Other Liabilities Retained or Assumed by Others. The Company’s subsidiaries have agreements with former owners of certain of their operating locations under which the former owners retained, assumed and/or agreed to indemnify such subsidiaries against certain environmental and other liabilities. The most significant of these agreements was entered into at Koppers Inc.’s formation on December 29, 1988 (the “Acquisition”). Under the related asset purchase agreement between Koppers Inc. and Beazer East, subject to certain limitations, Beazer East retained the responsibility for and agreed to indemnify Koppers Inc. against certain liabilities, damages, losses and costs, including, with certain limited exceptions, liabilities under and costs to comply with environmental laws to the extent attributable to acts or omissions occurring prior to the Acquisition and liabilities related to products sold by Beazer East prior to the Acquisition (the “Indemnity”). Beazer Limited, the parent company of Beazer East, unconditionally guaranteed Beazer East’s performance of the Indemnity pursuant to a guarantee (the “Guarantee”). In 1998, the parent company of Beazer East purchased an insurance policy under which the funding and risk of certain environmental and other liabilities relating to the former Koppers Company, Inc. operations of Beazer East (which includes locations purchased from Beazer East by Koppers Inc.) are underwritten by Centre Solutions (a member of the Zurich Group) and Swiss Re. Beazer East is a wholly-owned, indirect subsidiary of Heidelberg Cement AG.

	The Indemnity provides different mechanisms, subject to certain limitations, by which Beazer East is obligated to indemnify Koppers Inc. with regard to certain environmental, product and other liabilities and imposes certain conditions on Koppers Inc. before receiving such indemnification, including, in some cases, certain limitations regarding the time period as to which claims for indemnification can be brought. In July 2004, Koppers Inc. and Beazer East agreed to amend the environmental indemnification provisions of the December 29, 1988 asset purchase agreement to extend the indemnification period for pre-closing environmental liabilities through July 2019. As consideration for the amendment, Koppers Inc. paid Beazer East a total of $7.0 million and agreed to share toxic tort litigation defense costs arising from any sites acquired from Beazer East. The July 2004 amendment did not change the provisions of the Indemnity with respect to indemnification for non-environmental claims, such as product liability claims, which claims may continue to be asserted after July 2019.

	Qualified expenditures under the Indemnity are not subject to a monetary limit. Qualified expenditures under the Indemnity include (i) environmental cleanup liabilities required by third parties, such as investigation, remediation and closure costs, relating to pre-December 29, 1988 or (“Pre-Closing”) acts or omissions of Beazer East or its predecessors; (ii) environmental claims by third parties for personal injuries, property damages and natural resources damages relating to Pre-Closing acts or omissions of Beazer East or its predecessors; (iii) punitive damages for the acts or omissions of Beazer East and its predecessors without regard to the date of the alleged conduct, and (iv) product liability claims for products sold by Beazer East or its predecessors without regard to the date of the alleged conduct. If the third party claims described in sections (i) and (ii) above are not made by July 2019, Beazer East will not be required to pay the costs arising from such claims under the Indemnity. However, with respect to any such claims which are made by July 2019, Beazer East will continue to be responsible for such claims under the Indemnity beyond July 2019. The Indemnity provides for the resolution of issues between Koppers Inc. and Beazer East by an arbitrator on an expedited basis upon the request of either party. The arbitrator could be asked, among other things, to make a determination regarding the allocation of environmental responsibilities between Koppers Inc. and Beazer East. Arbitration decisions under the Indemnity are final and binding on the parties.

	Contamination has been identified at most manufacturing and other sites of the Company’s subsidiaries. Currently, at the properties acquired from Beazer East (which include all but two of the sites permitted under the Resource Conservation and Recovery Act (“RCRA”)), a significant portion of all investigative, cleanup and closure activities are being conducted and paid for by Beazer East pursuant to the terms of the Indemnity. In addition, other of Koppers Inc.’s sites are or have been operated under RCRA and various other environmental permits, and remedial and closure activities are being conducted at some of these sites.



	To date, the parties that retained, assumed and/or agreed to indemnify the Company against the liabilities referred to above, including Beazer East, have performed their obligations in all material respects. The Company believes that, for the last three years ended December 31, 2014, amounts paid by Beazer East as a result of its environmental remediation obligations under the Indemnity have averaged in total approximately $13 million per year. Periodically, issues have arisen between Koppers Inc. and Beazer East and/or other indemnitors that have been resolved without arbitration. Koppers Inc. and Beazer East engage in discussions from time to time that involve, among other things, the allocation of environmental costs related to certain operating and closed facilities.

	If for any reason (including disputed coverage or financial incapability) one or more of such parties fail to perform their obligations and the Company or its subsidiaries are held liable for or otherwise required to pay all or part of such liabilities without reimbursement, the imposition of such liabilities on the Company or its subsidiaries could have a material adverse effect on its business, financial condition, cash flows and results of operations. Furthermore, the Company could be required to record a contingent liability on its balance sheet with respect to such matters, which could result in a negative impact to the Company’s business, financial condition, cash flows and results of operations.

	Domestic Environmental Matters. Koppers Inc. has been named as one of the potentially responsible parties (“PRPs”) at the Portland Harbor CERCLA site located on the Willamette River in Oregon. Koppers Inc. currently maintains a coal tar pitch terminal near the site. Koppers Inc. has responded to an Environmental Protection Agency (“EPA”) information request and has executed a PRP agreement which outlines the process to develop an allocation of past and future costs among more than 80 parties to the site. Koppers Inc. believes it is a de minimus contributor at the site. Additionally, a separate natural resources damages assessment (“NRDA”) is being conducted by a local trustee group. The NRDA is intended to identify further information necessary to estimate liabilities for remediation based settlements of national resource damages (“NRD”) claims. Koppers Inc. may also incur liabilities under the NRD process and has entered into a separate process to develop an allocation of NRDA cost.

	In March 2012, a draft Feasibility Study (“FS”) was submitted to EPA by the Lower Willamette Group, a group of certain PRPs which has been conducting the investigation of the site. The draft FS identifies ten possible remedial alternatives which range in cost from approximately $170 million to $1.8 billion. The FS does not determine who is responsible for remediation costs or select remedies. The FS is under review by the EPA which will issue a final decision on the nature and extent of the final remediation. Responsibility for implementing and funding that work will be decided in the separate allocation process.

	In September 2009, Koppers Inc. received a general notice letter notifying it that it may be a PRP at the Newark Bay CERCLA site. In January 2010, Koppers Inc. submitted a response to the general notice letter asserting that Koppers Inc. is a de minimus party at this site.

	Other than the estimated costs of participating in the PRP group at the Portland Harbor and Newark Bay CERCLA sites totaling $0.7 million at December 31, 2014, the Company has not provided a reserve for these matters because there has not been a determination of the total cost of the investigations, the remediation that will be required, the amount of natural resources damages or how those costs will be allocated among the PRPs. Accordingly, the Company believes that it cannot reasonably determine the probability of a loss, and the amount of loss, if any, cannot be reasonably estimated. An unfavorable resolution of these matters may have a material adverse effect on the Company’s business, financial condition, cash flows and results of operations.

	Australian Environmental Matters. Soil and groundwater contamination has been detected at certain of the Company’s Australian facilities. At the Company’s tar distillation facility in Newcastle, New South Wales, Australia, soil contamination from an abandoned underground coal tar pipeline and other groundwater contamination have been detected at a property adjacent to the facility. In 2011, the Company and the owner of the adjacent property reached an agreement in which the Company will contribute $1.6 million and the owner of the adjacent property will contribute $7.5 million toward remediation of the property. The agreement provides that the Company will assume responsibility for the management of the remediation effort and will indemnify the current owner for any remediation costs in excess of its agreed contribution. At the completion of the remediation, the agreement provides that the property will be transferred to the Company. The remediation project commenced in 2011 and the Company has reserved its expected remaining remediation costs of $0.9 million and has recorded a receivable, net of cash collections, from the owner of the adjacent property of $0.8 million as of December 31, 2014.



	In December 2011, the Company ceased manufacturing operations at its Continental Carbon facility located in Kurnell, Australia. The Company has accrued its expected cost of site remediation resulting from the closure of $4.1 million as of December 31, 2014.

	Environmental Reserves Rollforward. The following table reflects changes in the accrued liability for environmental matters, of which $3.3 million and $8.2 million are classified as current liabilities at December 31, 2014 and 2013, respectively:



		Year Ended December 31,
		2014			2013
(Dollars in millions)
Balance at beginning of year			$11.90			$14.10
Expense			0.8			1.8
Reversal of reserves			(1.5	)		(1.2	)
Cash expenditures			(3.7	)		(0.9	)
Acquisition			0.7			0
Currency translation			(0.4	)		(1.9	)

Balance at end of year			$7.80			$11.90

Related_Party_Transactions

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions	21. Related Party Transactions
Related Party Transactions	As of December 31, 2014, the Company has loaned $9.5 million to TKK, a 30-percent owned company in China. The loan is repayable in November 2015 with six equal installments beginning June 2015.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
Selected Quarterly Financial Data (Unaudited)	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	22. Selected Quarterly Financial Data (Unaudited)

	The following is a summary of the quarterly results of operations for the years ended December 31, 2014 and 2013:



		Year Ended December 31, 2014
		1^stQuarter			2^ndQuarter			3^rdQuarter			4^thQuarter			Fiscal Year
	(Dollars in millions, except per share amounts)
	Statement of operations data:
	Net sales	$	331.4		$	356.8		$	440.1		$	426.7		$	1,555.00
	Operating profit		0.5			13.3			17.3			2.1			33.2
	Income (loss) from continuing operations		(0.1	)		0.8			(4.3	)		(36.4	)		(40.0	)
	Net income (loss)		(0.1	)		0.7			(4.2	)		(35.8	)		(39.4	)
	Net income (loss) attributable to Koppers^(c)		2.2			1.6			(2.7	)		(33.5	)		(32.4	)
	Common stock data:
	Earnings (loss) per common share attributable to Koppers common shareholders:^(a)
	Basic –
	Continuing operations	$	0.11		$	0.08		$	(0.14	)	$	(1.66	)	$	(1.61	)
	Discontinued operations		0			0			0			0.03			0.03

	Earnings (loss) per basic common share	$	0.11		$	0.08		$	(0.14	)	$	(1.63	)	$	(1.58	)

	Diluted –
	Continuing operations	$	0.11		$	0.08		$	(0.14	)	$	(1.66	)	$	(1.61	)
	Discontinued operations		0			0			0			0.03			0.03

	Earnings (loss) per diluted common share	$	0.11		$	0.08		$	(0.14	)	$	(1.63	)	$	(1.58	)

	Dividends declared per common share	$	0.25		$	0.25		$	0.25		$	0.25		$	1
	Price range of common stock:
	High	$	45.92		$	45.51		$	39.45		$	39.88		$	45.92
	Low		35.51			35.53			33.02			22.52			22.52





		Year Ended December 31, 2013
		1^stQuarter			2^ndQuarter			3^rdQuarter			4^thQuarter			Fiscal Year
	(Dollars in millions, except per share amounts)
	Statement of operations data:
	Net sales	$	370.4		$	370.9		$	395.2		$	341.8		$	1,478.30
	Operating profit^(b)		24.9			28.5			39.1			7.8			100.3
	Income from continuing operations		11.4			14.8			19.6			(5.6	)		40.2
	Net income		11.5			14.7			19.5			(5.6	)		40.1
	Net income attributable to Koppers		11			14.4			19.1			(4.1	)		40.4
	Common stock data:
	Earnings (loss) per common share attributable to Koppers common shareholders:^(a)
	Basic –
	Continuing operations	$	0.53		$	0.7		$	0.93		$	(0.20	)	$	1.96
	Discontinued operations		0			(0.01	)		0			0			0

	Earnings per basic common share	$	0.53		$	0.69		$	0.93		$	(0.20	)	$	1.96

	Diluted –
	Continuing operations	$	0.53		$	0.7		$	0.92		$	(0.20	)	$	1.94
	Discontinued operations		0			(0.01	)		0			0			0

	Earnings per diluted common share	$	0.53		$	0.69		$	0.92		$	(0.20	)	$	1.94

	Dividends declared per common share	$	0.25		$	0.25		$	0.25		$	0.25		$	1
	Price range of common stock:
	High	$	45.72		$	46.48		$	42.43		$	49.99		$	49.99
Low		38.7			37.45			34.69			41.61			34.69



(a)	The cumulative sum of quarterly basic and diluted net income per share amounts may not equal total basic and diluted net income per share amounts for the year due to differences in weighted average and equivalent shares outstanding for each of the periods presented.
(b)	In the fourth quarter of 2013, the Company recorded asset impairment charges totaling $11.9 million primarily consisting of write-downs related to the Company’s coal tar distillation facilities located in Uithoorn, the Netherlands; Tangshan, China; and Follansbee, West Virginia.
(c)	In the fourth quarter of 2014, the Company recorded a $24.3 million income tax charge related to a legal entity reorganization project.

Subsidiary_Guarantor_Informati

Subsidiary Guarantor Information for Koppers Inc. Senior Notes	12 Months Ended
	Dec. 31, 2014
Text Block [Abstract]
Subsidiary Guarantor Information for Koppers Inc. Senior Notes	23. Subsidiary Guarantor Information for Koppers Inc. Senior Notes

	On December 1, 2009, Koppers Inc. issued $300.0 million principal value of Senior Notes. Koppers Holdings and each of Koppers Inc.’s 100 percent-owned material domestic subsidiaries other than Koppers Assurance, Inc. fully and unconditionally guarantee the payment of principal and interest on the Senior Notes. The domestic guarantor subsidiaries include Koppers World-Wide Ventures Corporation, Koppers Delaware, Inc., Koppers Concrete Products, Inc., Concrete Partners, Inc., Koppers Performance Chemicals Inc., Koppers Railroad Structures Inc., Koppers NZ, LLC, Koppers-Nevada Limited Liability Company, Wood Protection LP, Wood Protection Management LLC and Koppers Asia LLC. Non-guarantor subsidiaries are owned directly or indirectly by Koppers Inc. or are owned directly or indirectly by Koppers World-Wide Ventures Corporation.

	The guarantee of a guarantor subsidiary will be automatically and unconditionally released and discharged in the event of:


		¡		any sale of the capital stock or substantially all of the assets of the guarantor subsidiary;


		¡		the designation of the guarantor subsidiary as an unrestricted subsidiary in accordance with the indenture governing the Senior Notes; and


		¡		the legal defeasance, covenant defeasance or satisfaction and discharge of the indenture governing the Senior Notes.

	Koppers Holdings depends on the dividends from the earnings of Koppers Inc. and its subsidiaries to generate the funds necessary to meet its financial obligations, including the payment of any declared dividend of Koppers Holdings. Koppers Inc.’s credit agreement prohibits it from making dividend payments to Koppers Holdings Inc. unless (1) such dividend payments are permitted by the indenture governing Koppers Inc.’s Senior Notes and (2) no event of default or potential default has occurred or is continuing under the credit agreement. The indenture governing Koppers Inc.’s Senior Notes restricts its ability to finance Koppers Holdings Inc.’s payment of dividends if (1) a default has occurred or would result from such financing, (2) a restricted subsidiary of Koppers Inc. which is not a guarantor under the indenture is not able to incur additional indebtedness (as defined in the indenture), and (3) the sum of all restricted payments (as defined in the indenture) have exceeded the permitted amount (referred to as the “basket”) at such point in time.



	The Koppers Inc. revolving credit facility agreement provides for a revolving credit facility of up to $500.0 million and a term loan of up to $300 million at variable rates. Borrowings under the revolving credit facility are secured by a first priority lien on substantially all of the assets of Koppers Inc. and its material domestic subsidiaries. The revolving credit facility agreement contains certain covenants for Koppers Inc. and its restricted subsidiaries that limit capital expenditures, additional indebtedness, liens, dividends, investments or acquisitions. In addition, such covenants give rise to events of default upon the failure by Koppers Inc. and its restricted subsidiaries to meet certain financial ratios.

	The amount of restricted net assets unavailable for distribution to Koppers Holdings Inc. by Koppers Inc. totals $20 million as of December 31, 2014. Cash dividends paid to Koppers Holdings Inc. by its subsidiaries totaled $23.6 million, $38.5 million and $27.6 million for the years ended December 31, 2014, 2013 and 2012, respectively.

	Condensed Consolidating Statement of Comprehensive (Loss) Income

	For the Year Ended December 31, 2014



			Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
											Guarantor				Subsidiaries				Adjustments
											Subsidiaries
	(Dollars in millions)
	Net sales		$	0			$	795.9			$	143			$	683.5			$	(67.4	)		$	1,555.00
	Cost of sales including depreciation and amortization			0				724.5				108.8				639				(66.7	)			1,405.60
	Selling, general and administrative			2.2				59.2				17.4				37.4				0				116.2

	Operating profit (loss)			(2.2	)			12.2				16.8				7.1				(0.7	)			33.2
	Other income (expense)			0				0.2				4.7				(0.6	)			(4.3	)			0
	Equity income of subsidiaries			(31.0	)			(15.9	)			(6.4	)			0				(53.3	)			0
	Interest expense			0				36.5				0				6.9				(4.3	)			39.1
	Income taxes			(0.8	)			(9.0	)			30.5				13.4				0				34.1

	Income from continuing operations			(32.4	)			(31.0	)			(15.4	)			(13.8	)			(52.6	)			(40.0	)
	Discontinued operations			0				0				(0.6	)			1.2				0				0.6
	Noncontrolling interests			0				0				0				(7.0	)			0				(7.0	)

	Net loss attributable to Koppers		$	(32.4	)		$	(31.0	)		$	(16.0	)		$	(5.6	)		$	(52.6	)		$	(32.4	)

	Comprehensive loss attributable to Koppers		$	(82.5	)		$	(81.1	)		$	(54.4	)		$	(35.1	)		$	170.6			$	(82.5	)




	Condensed Consolidating Statement of Comprehensive Income

	For the Year Ended December 31, 2013



			Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
											Guarantor				Subsidiaries				Adjustments
											Subsidiaries
	(Dollars in millions)
Net sales		$	0			$	843.7			$	61.8			$	622.2			$	(49.4	)		$	1,478.30
Cost of sales including depreciation and amortization			0				745.4				43.5				566.9				(49.5	)			1,306.30
Selling, general and administrative			1.9				41.5				0.7				27.6				0				71.7

Operating profit (loss)			(1.9	)			56.8				17.6				27.7				0.1				100.3
Other income (expense)			0				1.3				4.2				2.1				(4.1	)			3.5
Equity income of subsidiaries			41.7				17.5				11.4				0				(70.6	)			0
Interest expense			0				26.7				0				4.2				(4.1	)			26.8
Income taxes			(0.6	)			7.3				16.4				13.7				0				36.8

Income from continuing operations			40.4				41.6				16.8				11.9				(70.5	)			40.2
Discontinued operations			0				0.1				0				(0.2	)			0				(0.1	)
Noncontrolling interests			0				0				0				(0.3	)			0				(0.3	)

Net income attributable to Koppers		$	40.4			$	41.7			$	16.8			$	12			$	(70.5	)		$	40.4

Comprehensive income attributable to Koppers		$	52.3			$	53.5			$	8.4			$	13.8			$	(75.7	)		$	52.3


Condensed Consolidating Statement of Comprehensive Income

For the Year Ended December 31, 2012



		Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
										Guarantor				Subsidiaries				Adjustments
										Subsidiaries
(Dollars in millions)
Net sales		$	0			$	893.2			$	97.5			$	638.4			$	(74.1	)		$	1,555.00
Cost of sales including depreciation and amortization			0				786.6				78				562				(73.8	)			1,352.80
Selling, general and administrative			1.6				45.1				2.1				26.8				0				75.6

Operating profit (loss)			(1.6	)			61.5				17.4				49.6				(0.3	)			126.6
Other income (expense)			0				0.4				6.1				0.6				(5.2	)			1.9
Equity income of subsidiaries			66.6				40.8				28.8				0.1				(136.3	)			0
Interest expense			0				27.4				0				5.8				(5.3	)			27.9
Income taxes			(0.6	)			8.7				12.5				12.7				0				33.3

Income from continuing operations			65.6				66.6				39.8				31.8				(136.5	)			67.3
Discontinued operations			0				0				0				(0.1	)			0				(0.1	)
Noncontrolling interests			0				0				0				1.6				0				1.6

Net income attributable to Koppers		$	65.6			$	66.6			$	39.8			$	30.1			$	(136.5	)		$	65.6

Comprehensive income attributable to Koppers		$	73.7			$	74.8			$	44			$	32.4			$	(151.2	)		$	73.7




Condensed Consolidating Balance Sheet

December 31, 2014



		Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
										Guarantor				Subsidiaries				Adjustments
										Subsidiaries
(Dollars in millions)
ASSETS
Cash and cash equivalents		$	0			$	0			$	0.9			$	50.2			$	0			$	51.1
Receivables, net			0				75.7				20				103				0				198.7
Affiliated receivables			0.8				4.5				9.3				1.3				(15.9	)			0
Inventories, net			0				108.8				30.8				102.6				(1.0	)			241.2
Deferred tax assets			0				8				1				1.5				0				10.5
Other current assets			0				3				2.2				34.6				0				39.8

Total current assets			0.8				200				64.2				293.2				(16.9	)			541.3
Equity investments			74.5				767.2				213.5				3.6				(1,053.8	)			5
Property, plant and equipment, net			0				121.2				43.1				135.4				0				299.7
Goodwill			0				39.8				149.9				57.5				0				247.2
Intangible assets, net			0				2.2				128.1				37.4				0				167.7
Deferred tax assets			0				(1.0	)			1.1				7.7				0				7.8
Affiliated loan receivables			0				40.5				212				40.9				(293.4	)			0
Other noncurrent assets			0				19.1				5.2				0.9				0				25.2

Total assets		$	75.3			$	1,189.00			$	817.1			$	576.6			($	1,364.10	)		$	1,293.90

LIABILITIES AND EQUITY
Accounts payable		$	0.1			$	60.9			$	9			$	50.6			$	0			$	120.6
Affiliated payables			0				13.2				2.7				13.5				(29.4	)			0
Accrued liabilities			5.2				37.9				29.5				55				0				127.6
Short-term debt and current portion of long-term debt			0				30				0				13.9				0				43.9

Total current liabilities			5.3				142				41.2				133				(29.4	)			292.1
Long-term debt			0				764				0				42.6				0				806.6
Affiliated debt			0				145.5				35.9				112				(293.4	)			0
Other long-term liabilities			0				68.6				7.7				35				0				111.3

Total liabilities			5.3				1,120.10				84.8				322.6				(322.8	)			1,210.00
Koppers shareholders’ equity			70				68.9				732.3				240.1				(1,041.3	)			70
Noncontrolling interests			0				0				0				13.9				0				13.9

Total liabilities and equity		$	75.3			$	1,189.00			$	817.1			$	576.6			($	1,364.10	)		$	1,293.90




Condensed Consolidating Balance Sheet

December 31, 2013



		Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
										Guarantor				Subsidiaries				Adjustments
										Subsidiaries
(Dollars in millions)
ASSETS
Cash and cash equivalents		$	0			$	29.9			$	0.1			$	52.2			$	0			$	82.2
Receivables, net			0				75.6				9.3				82				0				166.9
Affiliated receivables			0.2				1.1				3.9				2.3				(7.5	)			0
Inventories, net			0				86.1				0				82.9				(0.2	)			168.8
Deferred tax assets			0				7.9				1.5				0.6				0				10
Other current assets			0				7.3				0.6				37.3				0				45.2

Total current assets			0.2				207.9				15.4				257.3				(7.7	)			473.1
Equity investments			174.7				333.5				182.9				4.6				(689.1	)			6.6
Property, plant and equipment, net			0				112.2				0				84.8				0				197
Goodwill			0				39.8				0				32.9				0				72.7
Deferred tax assets			0				2.4				(1.4	)			8.3				0				9.3
Affiliated loan receivables			0				8.5				123.8				40.9				(173.2	)			0
Other noncurrent assets			0				15				0				11.2				0				26.2

Total assets		$	174.9			$	719.3			$	320.7			$	440			$	(870.0	)		$	784.9

LIABILITIES AND EQUITY
Accounts payable		$	0			$	48.3			$	6.7			$	52.6			$	0			$	107.6
Affiliated payables			0				1.9				4				8.6				(14.5	)			0
Accrued liabilities			5.1				27.8				0.5				54.1				0				87.5

Total current liabilities			5.1				78				11.2				115.3				(14.5	)			195.1
Long-term debt			0				296.5				0				6.6				0				303.1
Affiliated debt			0				109.5				8.5				55.2				(173.2	)			0
Other long-term liabilities			0				67.6				2.5				26.8				0				96.9

Total liabilities			5.1				551.6				22.2				203.9				(187.7	)			595.1
Koppers shareholders’ equity			169.8				167.7				298.5				216.1				(682.3	)			169.8
Noncontrolling interests			0				0				0				20				0				20

Total liabilities and equity		$	174.9			$	719.3			$	320.7			$	440			$	(870.0	)		$	784.9




Condensed Consolidating Statement of Cash Flows

For the Year Ended December 31, 2014



		Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
										Guarantor				Subsidiaries				Adjustments
										Subsidiaries
(Dollars in millions)
Cash provided by (used in) operating activities		$	21.8			$	23.8			$	34.7			$	9.5			$	(54.3	)		$	35.5
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions			0				(518.5	)			(16.7	)			(59.9	)			14.8				(580.3	)
(Loans to) repayments from affiliates			0				(32.2	)			(38.9	)			0				71.1				0
Net cash proceeds from divestitures and asset sales			0				0.1				0.1				0.1				0				0.3

Net cash used in investing activities			0				(550.6	)			(55.5	)			(59.8	)			85.9				(580.0	)
Cash provided by (used in) financing activities:
Borrowings (repayments) of long-term debt			0				497				0				50.5				0				547.5
Borrowings (repayments) of affiliated debt			0				35.8				27.6				7.7				(71.1	)			0
Deferred financing costs			0				(11.1	)			0				0				0				(11.1	)
Other financing activities			0				0				0				1.4				0				1.4
Dividends paid			(20.5	)			(23.6	)			(6.1	)			(24.5	)			54.3				(20.4	)
Stock issued (repurchased)			(1.3	)			0				0				14.8				(14.8	)			(1.3	)

Net cash provided by (used in) financing activities			(21.8	)			498.1				21.5				49.9				(31.6	)			516.1
Effect of exchange rates on cash			0				(1.2	)			1				(2.5	)			0				(2.7	)

Net increase (decrease) in cash and cash equivalents			0				(29.9	)			1.7				(2.9	)			0				(31.1	)
Cash and cash equivalents at beginning of year			0				29.9				0.1				52.2				0				82.2

Cash and cash equivalents at end of period		$	0			$	0			$	1.8			$	49.3			$	0			$	51.1


Condensed Consolidating Statement of Cash Flows

For the Year Ended December 31, 2013



		Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
										Guarantor				Subsidiaries				Adjustments
										Subsidiaries
(Dollars in millions)
Cash provided by (used in) operating activities		$	37.8			$	278.7			$	130.1			$	47.6			$	(376.6	)		$	117.6
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions			0				(23.3	)			0				(51.9	)			0				(75.2	)
(Loans to) repayments from affiliates			0				(0.8	)			193.2				(1.7	)			(190.7	)			0
Net cash proceeds (payments) from divestitures and asset sales			0				1.3				0				1.6				0				2.9

Net cash used in investing activities			0				(22.8	)			193.2				(52.0	)			(190.7	)			(72.3	)
Cash provided by (used in) financing activities:
Borrowings (repayments) of long-term debt			0				0				0				6.6				0				6.6
Borrowings of affiliated long-term debt			0				(191.5	)			0.8				0				190.7				0
Deferred financing costs			0				(1.3	)			0				0				0				(1.3	)
Dividends paid			(20.5	)			(38.5	)			(324.0	)			(14.7	)			376.6				(21.1	)
Stock issued and repurchased			(17.3	)			0				0				0				0				(17.3	)
Other financing receipts			0				0.5				0				2.3				0				2.8

Net cash provided by (used in) financing activities			(37.8	)			(230.8	)			(323.2	)			(5.8	)			567.3				(30.3	)
Effect of exchange rates on cash			0				0				0				0.5				0				0.5

Net increase in cash and cash equivalents			0				25.1				0.1				(9.7	)			0				15.5
Cash and cash equivalents at beginning of year			0				4.8				0				61.9				0				66.7

Cash and cash equivalents at end of period		$	0			$	29.9			$	0.1			$	52.2			$	0			$	82.2




Condensed Consolidating Statement of Cash Flows

For the Year Ended December 31, 2012



		Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
										Guarantor				Subsidiaries				Adjustments
										Subsidiaries
(Dollars in millions)
Cash provided by (used in) operating activities		$	26.1			$	44.6			$	8.7			$	30.9			$	(32.5	)		$	77.8
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions			0				(21.3	)			0				(21.6	)			0				(42.9	)
Loan repayment by related party			0				0				0				2.2				0				2.2
(Loans to) repayments from affiliates			0				0.3				(8.4	)			(2.7	)			10.8				0
Net cash proceeds (payments) from divestitures and asset sales			0				0.4				0				0.4				0				0.8

Net cash used in investing activities			0				(20.6	)			(8.4	)			(21.7	)			10.8				(39.9	)
Cash provided by (used in) financing activities:
Repayments of long-term debt			0				(6.4	)			0				0				0				(6.4	)
Borrowings of affiliated long-term debt			0				13.3				(0.3	)			(2.2	)			(10.8	)			0
Deferred financing costs			0				(0.1	)			0				0				0				(0.1	)
Dividends paid			(19.5	)			(27.6	)			0				(4.9	)			32.5				(19.5	)
Stock issued and repurchased			(6.6	)			0				0				0				0				(6.6	)
Other financing receipts			0				1.6				0				3.7				0				5.3

Net cash provided by (used in) financing activities			(26.1	)			(19.2	)			(0.3	)			(3.4	)			21.7				(27.3	)
Effect of exchange rates on cash			0				0				0				2				0				2

Net increase in cash and cash equivalents			0				4.8				0				7.8				0				12.6
Cash and cash equivalents at beginning of year			0				0				0				54.1				0				54.1

Cash and cash equivalents at end of period		$	0			$	4.8			$	0			$	61.9			$	0			$	66.7

Schedule_II_Valuation_and_Qual

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
Schedule II - Valuation and Qualifying Accounts	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS

	For the years ended December 31, 2014, 2013 and 2012



		Balance at		Business		Increase			Net			Currency			Balance
		Beginning		Acquisition		(Decrease)			(Write-			Translation			at End
		of Year				to Expense			Offs)						of Year
									Recoveries
	(Dollars in millions)
	2014
	Allowance for doubtful accounts	$	3.6	$	2.6	$	(0.2	)	$	0		$	(0.4	)	$	5.6

	Inventory obsolescence reserves	$	1.7	$	0.8	$	1		$	0		$	(0.1	)	$	3.4

	Deferred tax valuation allowance	$	19.7	$	1.5	$	11.4		$	0		$	(0.2	)	$	32.4

	2013
	Allowance for doubtful accounts	$	3.7	$	0	$	(0.2	)	$	0		$	0.1		$	3.6

	Inventory obsolescence reserves	$	1.1	$	0	$	0.7		$	0		$	(0.1	)	$	1.7

	Deferred tax valuation allowance	$	17.4	$	0	$	2.6		$	(0.2	)	$	(0.1	)	$	19.7

	2012
	Allowance for doubtful accounts	$	0.3	$	0	$	3.2		$	0		$	0.2		$	3.7

	Inventory obsolescence reserves	$	1.4	$	0	$	0.5		$	(0.8	)	$	0		$	1.1

	Deferred tax valuation allowance	$	10.2	$	0	$	8.8		$	(1.6	)	$	0		$	17.4

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation	Basis of presentation – The consolidated financial statements include the accounts of the Company and all majority-owned subsidiaries for which the Company is deemed to exercise control over its operations. All significant intercompany transactions have been eliminated in consolidation. The Company’s investments in 20 percent to 50 percent-owned companies in which it has the ability to exercise significant influence over operating and financial policies are accounted for using the equity method of accounting. Accordingly, the Company’s share of the earnings of these companies is included in the accompanying consolidated statement of income. Certain prior period amounts in the notes to the consolidated financial statements have been reclassified to conform to the current period’s presentation.
Use of Estimates	Use of estimates – Accounting principles generally accepted in the U.S. require management to make estimates and judgments that affect the reported amounts of assets and liabilities and the disclosure of contingencies on the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Estimates have been prepared on the basis of the most current and best available information and actual results could differ materially from these estimates.
Foreign Currency Translation	Foreign currency translation – For consolidated entities outside of the U.S. that prepare financial statements in currencies other than the U.S. dollar, results of operations and cash flows are translated at average exchange rates during the period, and asset and liabilities are translated at end-of-period exchange rates. Cumulative translation adjustments are included as a separate component of accumulated other comprehensive loss in shareholders’ equity.

	Foreign currency transaction gains and losses result from transactions denominated in a currency which is different than the currency used by the entity to prepare its financial statements. Foreign currency transaction gains (losses) were $0.6 million, $(0.5) million and $(1.7) million for the years ended December 31, 2014, 2013 and 2012, respectively.
Revenue Recognition	Revenue recognition – The Company recognizes revenue when the risks and rewards of ownership and title to the product have transferred to the customer. Revenue recognition generally occurs at the point of shipment; however in certain circumstances as shipping terms dictate, revenue is recognized at the point of destination. Shipping and handling costs are included as a component of cost of sales.

	The Company recognizes revenue related to the procurement of certain untreated railroad crossties upon transfer of title to the customer, which occurs upon delivery to the Company’s plant and acceptance by the customer. Service revenue, consisting primarily of wood treating services, is recognized at the time the service is provided. Payment on sales of untreated railroad crossties and wood treating services are generally due within 30 days of the invoice date. The Company’s recognition of revenue with respect to untreated crossties meets all the recognition criteria of Securities and Exchange Commission Staff Accounting Bulletin Topic 13.A.3., including transfer of title and risk of ownership, the existence of fixed purchase commitments and delivery schedules established by the customer, and the completion of all performance obligations by the Company. Revenue recognized for untreated crosstie sales for the years ended December 31, 2014, 2013 and 2012 amounted to $93.4 million, $108.3 million and $109.0 million, respectively.
Research & Development	Research and development – Research and development costs are expensed as incurred and are included in selling, general and administrative expenses. These costs totaled $3.1 million in 2014, $2.4 million in 2013 and $2.3 million in 2012.
Cash and Cash Equivalents	Cash and cash equivalents – Cash and cash equivalents include cash on hand and on deposit and investments in highly liquid investments with an original maturity of 90 days or less.
Accounts Receivable	Accounts receivable – The Company maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. In circumstances where the Company becomes aware of a specific customer’s inability to meet its financial obligations to Koppers, a specific reserve for bad debts is recorded against amounts due. If the financial condition of the Company’s customers were to deteriorate, resulting in an inability to make payments, additional allowances may be required.
Inventories	Inventories – Inventories are carried at lower of cost or market on a worldwide basis. In the U.S., inventory cost (excluding miscellaneous types of inventory) is determined primarily utilizing the last-in, first-out (“LIFO”) basis. Inventory cost outside the U.S. is determined utilizing the first-in, first-out (“FIFO”) basis. Market represents replacement cost for raw materials and net realizable value for work in process and finished goods. LIFO inventories constituted approximately 61 percent and 62 percent of the FIFO inventory value at December 31, 2014 and 2013, respectively.
Property, Plant & Equipment	Property, plant and equipment – Property, plant and equipment are recorded at purchased cost and include improvements which significantly increase capacities or extend useful lives of existing plant and equipment. Depreciation expense is calculated by applying the straight-line method over estimated useful lives. Estimated useful lives for buildings generally range from 10 to 20 years and depreciable lives for machinery and equipment generally range from 3 to 10 years. Net gains and losses related to asset disposals are recognized in earnings in the period in which the disposal occurs. Routine repairs, replacements and maintenance are expensed as incurred.
Property, Plant & Equipment	The Company periodically evaluates whether current facts and circumstances indicate that the carrying value of its depreciable long-lived assets may not be recoverable. If an asset, or logical grouping of assets, is determined to be impaired, the asset is written down to its fair value using discounted future cash flows and, if available, quoted market prices.
Goodwill & Other Intangible Assets	Goodwill and other intangible assets – Goodwill and other purchased intangible assets are included in the identifiable assets of the business segment to which they have been assigned. The Company performs impairment tests annually for goodwill, and more often as circumstances require. When it is determined that impairment has occurred, an appropriate charge to earnings is recorded. The Company performed its annual impairment test in the fourth quarters of 2014 and 2013 and determined that the estimated fair values substantially exceeded the carrying values of all the reporting units and accordingly, there was no impairment of goodwill.
Goodwill & Other Intangible Assets	Identifiable intangible assets, other than goodwill, are recorded at cost. Identifiable intangible assets that do not have indefinite lives are amortized on a straight-line basis over their estimated useful lives.
Deferred Income Taxes	Deferred income taxes – Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. The effect on deferred tax assets and liabilities of a change in tax laws is recognized in earnings in the period the new laws are enacted. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets unless it is more likely than not that such assets will be realized. Deferred tax liabilities have not been recognized for the undistributed earnings of certain foreign subsidiaries because management intends to permanently reinvest such earnings in foreign operations.
Self-insured Liabilities	Self-insured liabilities – The Company is self-insured for property, casualty and workers’ compensation exposures up to various stop-loss coverage amounts. Losses are accrued based upon the Company’s estimates of the liability for the related deductibles of claims incurred. Such estimates utilize actuarial methods based on various assumptions, which include but are not limited to, the Company’s historical loss experience and projected loss development factors. In 2014 and 2013, reversals of self-insured liabilities occurred as a result of favorable loss trends related to self-insured claims.


		2014			2013
	(Dollars in millions)
	Self-insured liabilities at beginning of year	$	8.4		$	7.6
	Expense		2.4			2.5
	Reversal of self-insured liabilities		(0.8	)		(0.4	)
	Cash expenditures		(1.8	)		(1.3	)

	Self-insured liabilities at end of year	$	8.2		$	8.4

Derivative Financial Instruments	Derivative financial instruments – The Company uses swap contracts to manage copper price risk associated with forecasted purchases of materials used in the Company’s manufacturing processes. The Company uses forward exchange contracts to hedge exposure to currency exchange rate changes on transactions and other commitments denominated in a foreign currency. Contracts are not held for trading or speculative purposes. The Company recognizes the fair value of the swap contracts and forward contracts as an asset or liability at each reporting date. The Company designates the swap contracts as cash flow hedges and the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive (loss) earnings until it is reclassified into earnings when the hedged transaction affects earnings. Gains and losses from hedge ineffectiveness are recognized in current earnings. Because the Company has not elected to designate the forward exchange contracts for hedge accounting treatment, changes in the fair value of the forward exchange contracts are recognized immediately in earnings.
Asset Retirement Obligations	Asset retirement obligations – Asset retirement obligations are initially recorded at fair value and are capitalized as part of the cost of the related long-lived asset when sufficient information is available to estimate fair value. The capitalized costs are subsequently charged to depreciation expense over the estimated useful life of the related long-lived asset. The fair value of the obligation is determined by calculating the discounted value of expected future cash flows and accretion expense is recorded each month to ultimately increase this obligation to full value.
	The Company recognizes asset retirement obligations for the removal and disposal of residues; dismantling of certain tanks required by governmental authorities; cleaning and dismantling costs for owned rail cars; cleaning costs for leased rail cars and barges; and site demolition.
	The following table describes changes to the Company’s asset retirement obligation liabilities at December 31, 2014 and 2013:


		2014			2013
	(Dollars in millions)
	Asset retirement obligation at beginning of year	$	23.2		$	21.5
	Accretion expense		2.3			1.2
	Revision in estimated cash flows		10.3			6.7
	Cash expenditures		(4.6	)		(5.6	)
	Currency translation		(0.7	)		(0.6	)

	Asset retirement obligation at end of year	$	30.5		$	23.2

Litigation & Contingencies	Litigation and contingencies – Amounts associated with litigation and contingencies are accrued when management, after taking into consideration the facts and circumstances of each matter including any settlement offers, has determined that it is probable that a liability has been incurred and the amount of loss can be reasonably estimated. Legal costs for litigation are expensed as incurred with the exception of legal fees relating the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) sites.
Other Current Assets	Other current assets – Included in other current assets are prepaid expenses totaling $20.6 million and $17.3 million at December 31, 2014 and 2013, respectively.
Environmental Liabilities	Environmental liabilities – The Company accrues for remediation costs and penalties when the responsibility to remediate is probable and the amount of related cost is reasonably estimable. If only a range of potential liability can be estimated and no amount within the range is more probable than another, the accrual is recorded at the low end of that range. Remediation liabilities are discounted if the amount and timing of the cash disbursements are readily determinable.
Deferred Revenue from Extended Product Warranty Liabilities	Deferred revenue from extended product warranty liabilities – The Company defers revenues associated with extended product warranty liabilities based on historical loss experience and sales of extended warranties on certain products. The following table describes changes to the Company’s deferred revenue at December 31, 2014 and 2013:


		2014			2013
	(Dollars in millions)
	Deferred revenue at beginning of year	$	3.2		$	3.9
	Revenue earned		(0.7	)		(0.7	)

	Deferred revenue at end of year	$	2.5		$	3.2

Stock-based Compensation	Stock-based compensation – The Company records compensation cost over the vesting period for share-based payments to employees at an amount equivalent to the grant date fair value of the stock award. No compensation cost is recognized for any stock awards that are forfeited in the event the recipient fails to meet the vesting requirements.
New Accounting Pronouncements	In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 requires an entity to recognize revenue in a manner that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that core principle, the amendment provides five steps that an entity should apply when recognizing revenue. The amendment also specifies the accounting of some costs to obtain or fulfill a contract with a customer and expands the disclosure requirements around contracts with customers. An entity can either adopt this amendment retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying the update recognized at the date of initial application. The amendment is effective for annual reporting periods beginning after December 15, 2016. Early adoption is not permitted. The Company is currently evaluating the impact of the adoption of ASU 2014-09 on the Company’s financial statements.
New Accounting Pronouncements	In August 2014, the FASB issued ASU No. 2014-15, “Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern” (“ASU 2014-15”), which requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued and provides guidance on determining when and how to disclose going concern uncertainties in the financial statements. Certain disclosures will be required if conditions give rise to substantial doubt about an entity’s ability to continue as a going concern. ASU 2014-15 applies to all entities and is effective for annual and interim reporting periods ending after December 15, 2016, with early adoption permitted. We do not expect that the adoption of this standard will have a material effect on the Company’s financial statements.
Recently-Enacted Tax Regulations	Recently-Enacted Tax Regulations
Recently-Enacted Tax Regulations	On September 13, 2013, Treasury and the Internal Revenue Service issued final regulations regarding the deduction and capitalization of expenditures related to tangible property. The final regulations under Internal Revenue Code Sections 162, 167 and 263(a) apply to amounts paid to acquire, produce, or improve tangible property as well as dispositions of such property and are generally effective for tax years beginning on or after January 1, 2014. We have evaluated these regulations and determined they do not have a material impact on our consolidated results of operations, cash flows or financial position.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
Summary of Significant Accounting Policies (Tables)	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Self-Insured Liabilities	Company’s historical loss experience and projected loss development factors. In 2014 and 2013, reversals of self-insured liabilities occurred as a result of favorable loss trends related to self-insured claims.


		2014			2013
	(Dollars in millions)
	Self-insured liabilities at beginning of year	$	8.4		$	7.6
	Expense		2.4			2.5
	Reversal of self-insured liabilities		(0.8	)		(0.4	)
	Cash expenditures		(1.8	)		(1.3	)

	Self-insured liabilities at end of year	$	8.2		$	8.4

Summary of Asset Retirement Obligation Liabilities	The following table describes changes to the Company’s asset retirement obligation liabilities at December 31, 2014 and 2013:


		2014			2013
	(Dollars in millions)
	Asset retirement obligation at beginning of year	$	23.2		$	21.5
	Accretion expense		2.3			1.2
	Revision in estimated cash flows		10.3			6.7
	Cash expenditures		(4.6	)		(5.6	)
	Currency translation		(0.7	)		(0.6	)

	Asset retirement obligation at end of year	$	30.5		$	23.2

Summary of Changes to Deferred Revenue	The following table describes changes to the Company’s deferred revenue at December 31, 2014 and 2013:


		2014			2013
	(Dollars in millions)
	Deferred revenue at beginning of year	$	3.2		$	3.9
	Revenue earned		(0.7	)		(0.7	)

	Deferred revenue at end of year	$	2.5		$	3.2

Plant_Closures_and_Discontinue1

Plant Closures and Discontinued Operations (Tables)	12 Months Ended
Plant Closures and Discontinued Operations (Tables)	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Summary of Restructuring Activities and Related Reserves	Details of the restructuring activities and related reserves are as follows:


		Severance			Environmental			Site			Other			Total
		and			remediation			demolition
		employee
		benefits
	(Dollars in millions)
	Reserve at December 31, 2012	$	0.2		$	6.7		$	6.3		$	0.1		$	13.3
	Reversal of accrued charges		(0.1	)		0			(0.3	)		0			(0.4	)
	Cash paid		0			(0.1	)		(2.0	)		(0.1	)		(2.2	)
	Currency translation		0			(1.0	)		(0.7	)		0			(1.7	)

	Reserve at December 31, 2013	$	0.1		$	5.6		$	3.3		$	0		$	9
	Accrual		9.8			0			3.2			0.1			13.1
	Reversal of accrued charges		0			(1.1	)		(0.9	)		0			(2.0	)
	Cash paid		(9.7	)		0			(1.3	)		0			(11.0	)
	Currency translation		(0.2	)		(0.4	)		(0.4	)		0			(1.0	)

	Reserve at December 31, 2014	$	0		$	4.1		$	3.9		$	0.1		$	8.1

Business_Acquisitions_Tables

Business Acquisitions (Tables)	12 Months Ended
Business Acquisitions (Tables)	Dec. 31, 2014
Business Combinations [Abstract]
Schedule of Company's Preliminary Fair Value Estimates for Osmose Entities	The following table summarizes the Company’s preliminary fair value estimates for the Osmose Entities:



	(Dollars in millions)	Initial
	(Dollars in millions)	Allocation
	Cash and cash equivalents	$	27.2
	Accounts receivable, net		60.3
	Inventories, net		51.9
	Other current assets		3.3
	Property, plant and equipment		57.9
	Goodwill		178.8
	Intangible assets		158.9
	Other assets		10.3

	Total assets acquired		548.6

	Accounts payable		21.2
	Accrued liabilities		18.1
	Other liabilities		15.2

	Total liabilities assumed		54.5

	Net assets acquired	$	494.1

Summary of Company's Revenue and Net Income from Continuing Operations	The following unaudited pro forma information presents a summary of the Company’s revenues and net income from continuing operations as if the acquisition occurred on January 1, 2013. The unaudited pro forma information is not necessarily indicative of operating results that would have been achieved had the acquisition been completed as of January 1, 2013 and does not intend to project the future financial results of the Company after the acquisition of the Osmose Entities. The unaudited pro forma information is based on certain assumptions, which management believes are reasonable, and do not reflect the cost of any integration activities or the benefits from the acquisition and synergies that may be derived from any integration activities.



		Year Ended December 31,
		2014			2013
	(Dollars in millions)
	Revenue	$	1,819.60		$	1,864.10
	(Loss) income from continuing operations attributable to Koppers		(13.0	)		41.5

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Schedule of Company's Financial Instruments	Carrying amounts and the related estimated fair values of the Company’s financial instruments as of December 31, 2014 and 2013 are as follows:



			December 31, 2014				December 31, 2013
			Fair Value		Carrying		Fair Value		Carrying
			Fair Value		Value		Fair Value		Value
	(Dollars in millions)
	Financial assets:
	Cash and cash equivalents, including restricted cash		$	51.1	$	51.1	$	82.2	$	82.2
	Investments and other assets^(a)			1.5		1.5		1.4		1.4
	Financial liabilities:
	Long-term debt (including current portion)		$	862.1	$	850.5	$	331.2	$	303.1



	(a)	Excludes equity method investments.

Earnings_per_Common_Share_Tabl

Earnings per Common Share (Tables)	12 Months Ended
Earnings per Common Share (Tables)	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Earnings per Common Share	The following table sets forth the computation of basic and diluted earnings per common share:



		Year Ended December 31,
		2014			2013			2012
	(Dollars in millions, except share amounts, in thousands, and per share amounts)
	Net (loss) income attributable to Koppers	$	(32.4	)	$	40.4		$	65.6
	Less: discontinued operations		0.6			(0.1	)		(0.1	)

	(Loss) income from continuing operations attributable to Koppers	$	(33.0	)	$	40.5		$	65.7

	Weighted average common shares outstanding:
	Basic		20,463			20,575			20,681
	Effect of dilutive securities		0			240			246

	Diluted		20,463			20,815			20,927

	(Loss) earnings per common share – continuing operations:
	Basic (loss) earnings per common share	$	(1.61	)	$	1.96		$	3.18
	Diluted (loss) earnings per common share		(1.61	)		1.94			3.14

	Other data:
	Antidilutive securities excluded from computation of diluted earnings per common share		362			240			194

Stockbased_Compensation_Tables

Stock-based Compensation (Tables)	12 Months Ended
Stock-based Compensation (Tables)	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Performance Stock Units	The following table shows a summary of the performance stock units as of December 31, 2014:


	Performance Period	Minimum			Target			Maximum
	Performance Period	Shares			Shares			Shares
	2012 – 2014		0			87,039			130,559
	2013 – 2015		0			85,207			127,811
	2014 – 2016		0			102,149			153,224

Summary of Status and Activity of Non-Vested Stock Awards	The following table shows a summary of the status and activity of non-vested stock awards for the year ended December 31, 2014:


		Restricted			Performance			Total			Weighted Average
		Stock Units			Stock Units			Stock Units			Grant Date Fair
											Value per Unit
	Non-vested at January 1, 2014		148,836			319,984			468,820		$	40.3
	Granted		99,867			108,506			208,373		$	37.92
	Credited from dividends		3,813			8,425			12,238		$	38.52
	Vested		(90,915	)		(132,317	)		(223,232	)	$	40
	Forfeited		(12,695	)		(24,218	)		(36,913	)	$	39.51

	Non-vested at December 31, 2014		148,906			280,380			429,286		$	39.31

Stock Options Fair Value Assumptions	The fair value of stock options on the date of grant is calculated using the Black-Scholes-Merton model and the assumptions listed below:


		February 2014 Grant			February 2013 Grant			February 2012 Grant
	Grant date price per share of option award	$	37.93		$	42.76		$	38.21
	Expected dividend yield per share		2.75	%		2.75	%		2.75	%
	Expected life in years		6.5			6.5			6.5
	Expected volatility		52.14	%		53.77	%		55.06	%
	Risk-free interest rate		1.98	%		1.29	%		1.34	%
	Grant date fair value per share of option awards	$	15.26		$	17.28		$	15.82

Summary of Status and Activity of Stock Options	The following table shows a summary of the status and activity of stock options for the year ended December 31, 2014:


		Options			Weighted Average			Weighted Average			Aggregate Intrinsic
					Exercise Price			Remaining			Value (in millions)
					per Option			Contractual Term
								(in years)
	Outstanding at December 31, 2013		421,080		$	35.96
	Granted		106,658		$	37.93
	Exercised		(26,349	)	$	25.51
	Expired		(17,870	)	$	40.14
	Forfeited		(34,707	)	$	39.75

	Outstanding at December 31, 2014		448,812		$	36.58			5.96		$	0.2

	Exercisable at December 31, 2014		276,824		$	34.71			4.54		$	0.2

Schedule of Stock-based Compensation Expense Recognized and Cash Received from Exercise of Stock Options	Total stock-based compensation expense recognized and cash received from the exercise of stock options for the three years ended December 31, 2014 is as follows:



		Year Ended December 31,
		2014			2013			2012

	(Dollars in millions)
	Stock-based compensation expense recognized:
	Selling, general and administrative expenses	$	4.7		$	4.3		$	6.9
	Less related income tax benefit		1.9			1.7			2.8

	Decrease in net income attributable to Koppers	$	2.8		$	2.6		$	4.1

	Cash received from the exercise of stock options	$	0.7		$	0.2		$	1.6

Segment_Information_Tables

Segment Information (Tables)	12 Months Ended
Segment Information (Tables)	Dec. 31, 2014
Segment Reporting [Abstract]
Summary of Results of Segment Operations	The following table sets forth certain sales and operating data, net of all intersegment transactions, for the Company’s segments for the periods indicated:



			Year Ended December 31,
			2014			2013			2012
	(Dollars in millions)
	Revenues from external customers:
	Carbon Materials and Chemicals		$	833.7		$	906.1		$	999.7
	Railroad and Utility Products and Services			597.8			572.2			555.3
	Performance Chemicals			123.5			0			0

	Total		$	1,555.00		$	1,478.30		$	1,555.00

	Intersegment revenues:
	Carbon Materials and Chemicals		$	84.8		$	94.2		$	106.5
	Performance Chemicals			3			0			0

	Total		$	87.8		$	94.2		$	106.5

	Depreciation and amortization^(a):
	Carbon Materials and Chemicals		$	25		$	18.2		$	16.9
	Railroad and Utility Products and Services			11.9			11.5			10.7
	Performance Chemicals			7.1			0			0

	Total		$	44		$	29.7		$	27.6

	Operating profit:
	Carbon Materials and Chemicals		$	(5.3	)	$	43.9		$	83.1
	Railroad and Utility Products and Services			53.6			58.3			45.1
	Performance Chemicals			1.6			0			0
	Corporate^(b)			(16.7	)		(1.9	)		(1.6	)

	Total		$	33.2		$	100.3		$	126.6

	Capital expenditures (including acquisitions):
	Carbon Materials and Chemicals		$	63.7		$	58		$	17.3
	Railroad and Utility Products and Services			44.5			15.9			25
	Performance Chemicals			471.1			0			0
	Corporate			0.7			1.3			0.6

	Total		$	580		$	75.2		$	42.9



	(a)	Excludes impairment charges of $4.7 and $11.9 million in 2014 and 2013, respectively, for Carbon Materials and Chemicals and $0.6 million in 2012 for Railroad and Utility Products and Services.
	(b)	Operating loss for Corporate includes general and administrative costs for Koppers Holdings Inc., the parent company of Koppers Inc., acquisition and acquisition-related integration costs.
Summary of Tangible and Intangible Assets by Segments	The following table sets forth certain tangible and intangible assets allocated to each of the Company’s segments as of the dates indicated:


			December 31,
			2014			2013
	(Dollars in millions)
	Assets:
	Carbon Materials and Chemicals		$	514.6		$	535.5
	Railroad and Utility Products and Services			275.2			179.3
	Performance Chemicals			469			0

	Segment assets			1,258.80			714.8
	Cash and cash equivalents			0			30
	Income tax receivable			0			9
	Deferred taxes			10			13.3
	Deferred financing costs			14.5			7.2
	Property, plant and equipment, net			3.9			3.8
	Deferred charges			1.6			2.6
	Other			5.1			4.2

	Total		$	1,293.90		$	784.9

	Goodwill:
	Carbon Materials and Chemicals		$	65.5		$	68
	Railroad and Utility Products and Services			9.3			4.7
	Performance Chemicals			172.4			0

	Total		$	247.2		$	72.7

Schedule of Revenues and Long-Lived Assets by Geographic Area	Revenues and Long-lived Assets by Geographic Area


			Year			Revenue			Long-lived
			Year			Revenue			assets
	(Dollars in millions)
	United States			2014		$	833		$	537.1
				2013			782.5			169.1
				2012			827.6			162.9
	Australasia			2014			349			160.3
				2013			348.3			100.6
				2012			318.9			72.4
	Europe			2014			201.1			47.5
				2013			225.1			32.8
				2012			247.8			36.3
	Other countries			2014			171.9			0
				2013			122.4			0
				2012			160.7			0

	Total			2014		$	1,555.00		$	744.9
				2013		$	1,478.30		$	302.5
				2012		$	1,555.00		$	271.6

Schedule of Segment Revenues for Significant Product Lines
	Segment Revenues for Significant Product Lines



			Year Ended December 31,
			2014			2013			2012
	(Dollars in millions)
	Carbon Materials and Chemicals:
	Carbon pitch		$	330.2		$	384.7		$	442.4
	Creosote and carbon black feedstock			213.7			228.2			233.8
	Phthalic anhydride			91.4			98.6			120
	Naphthalene			73.5			64.5			60.3
	Other products			124.9			130.1			143.2

				833.7			906.1			999.7
	Railroad and Utility Products and Services:
	Railroad crossties			342.2			331.1			341.1
	Utility poles			96.1			119.3			101.3
	Creosote			51.2			61.4			57
	Rail joint bars			27.2			24.5			25.6
	Railroad infrastructure services			14.8			0			0
	Other products			66.3			35.9			30.3

				597.8			572.2			555.3
	Performance Chemicals:
	Wood preservative products			107			0			0
	Other products			16.5			0			0

				123.5			0			0

	Total		$	1,555.00		$	1,478.30		$	1,555.00

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Summary of Income Tax Provision	Components of the Company’s income tax provision from continuing operations are as follows:


		Years Ended December 31,
		2014			2013			2012
	(Dollars in millions)
	Current:
	Federal	$	17.5		$	3.5		$	15.7
	State		0.3			0.6			1.3
	Foreign		14.6			14			8.6

	Total current tax provision		32.4			18.1			25.6
	Deferred:
	Federal		3.1			16.4			4.9
	State		0			2.5			(1.2	)
	Foreign		(1.4	)		(0.2	)		4

	Total deferred tax provision (benefit)		1.7			18.7			7.7

	Total income tax provision	$	34.1		$	36.8		$	33.3

Summary of Income Taxes Reconciled with Federal Statutory Rate	The provision for income taxes is reconciled with the federal statutory rate as follows:



		Years Ended December 31,
		2014			2013			2012
	Federal income tax rate		35	%		35	%		35	%
	State income taxes, net of federal tax benefit		(4.8	)		2.1			(0.5	)
	Foreign earnings taxed at different rates		(440.0	)		15.5			0.5
	Domestic production activities deduction		40.8			(2.0	)		(2.7	)
	Deferred tax adjustments		3.2			(0.2	)		(0.3	)
	Change in tax contingency reserves		(15.2	)		(1.5	)		1.2
	Legal entity tax restructuring project		(1,503.2	)		0			0
	Foreign tax credits		1,203.40			(1.1	)		(0.6	)
	Changes to foreign repatriation plans		104			0			0
	Other		(1.2	)		0			0.5

			(578.0	)%		47.8	%		33.1	%

Summary of Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities are as follows:



		December 31,
		2014			2013
	(Dollars in millions)
	Deferred tax assets:
	Pension and other postretirement benefits obligations	$	19.2		$	10.3
	Tax credits		16.1			10.3
	Net operating loss benefit		14.6			10
	Reserves, including insurance, environmental and deferred revenue		12.4			16.5
	Asset retirement obligations		7.5			6.8
	Accrued employee compensation		6.7			9.4
	Book/tax inventory accounting differences		3.6			3.3
	Book over tax depreciation and amortization		3.2			1.3
	Capital loss benefit		1.1			1.1
	Other		6.4			2.2
	Valuation allowance		(32.4	)		(19.7	)

	Total deferred tax assets		58.4			51.5
	Deferred tax liabilities:
	Tax over book depreciation and amortization		49			35.4
	Unremitted earnings of foreign subsidiaries		0.5			6.8
	Tax/book inventory accounting differences		0.2			1.1
	Other		0.6			3.7

	Total deferred tax liabilities		50.3			47

	Net deferred tax assets	$	8.1		$	4.5

Summary of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:



		December 31,
		2014			2013			2012
	(Dollars in millions)
	Balance at beginning of year	$	6.1		$	7.7		$	9.9
	Additions based on tax provisions related to the current year		0.6			0.4			0.5
	Additions for tax provisions of prior years		0.1			0.4			1.3
	Additions as a result of acquisitions		1.6			0			0
	Reductions of tax provisions of prior years		(0.6	)		(0.8	)		(0.5	)
	Reductions as a result of payments and settlements		0			(1.1	)		(2.8	)
	Reductions as a result of a lapse of the applicable statute of limitations		(0.6	)		(0.5	)		(0.7	)

	Balance at end of year	$	7.2		$	6.1		$	7.7

Inventories_Tables

Inventories (Tables)	12 Months Ended
Inventories (Tables)	Dec. 31, 2014
Inventory Disclosure [Abstract]
Components of Inventories	Inventories as of December 31, 2014 and 2013 were as follows:



		December 31,
		2014		2013
	(Dollars in millions)
	Raw materials	$	191.1	$	105.4
	Work in process		2.6		19.2
	Finished goods		103.6		94.8

			297.3		219.4
	Less revaluation to LIFO		56.1		50.6

	Net	$	241.2	$	168.8

Equity_Investments_Tables

Equity Investments (Tables)	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Equity Earnings (Losses) and Dividends Received	Equity in (losses) earnings for the three years ended December 31, 2014 were as follows:


		Equity
		(loss) income
	(Dollars in millions)
	2014	$	(1.6	)
	2013		0.8
	2012		0.8

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	12 Months Ended
Property, Plant and Equipment (Tables)	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment as of December 31, 2014 and 2013 were as follows:



		December 31,
		2014		2013
	(Dollars in millions)
	Land	$	18.7	$	9.1
	Buildings		45.3		30.6
	Machinery and equipment		678.6		608.1

			742.6		647.8
	Less accumulated depreciation		442.9		450.8

	Net	$	299.7	$	197

Goodwill_and_Other_Identifiabl1

Goodwill and Other Identifiable Intangible Assets (Tables)	12 Months Ended
Goodwill and Other Identifiable Intangible Assets (Tables)	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Carrying Amount of Goodwill	The change in the carrying amount of goodwill attributable to each business segment for the years ended December 31, 2014 and December 31, 2013 was as follows:


		Carbon Materials and			Railroad and			Performance			Total
		Chemicals			Utility Products			Chemicals
					and Services
	(Dollars in millions)
	Balance at December 31, 2012	$	70.2		$	5.4		$	0		$	75.6
	Currency translation		(2.2	)		(0.7	)		(0.0	)		(2.9	)

	Balance at December 31, 2013	$	68		$	4.7		$	0		$	72.7
	Acquisitions		0			5.2			175.4			180.6
	Currency translation		(2.5	)		(0.6	)		(3.0	)		(6.1	)
	Balance at December 31, 2014	$	65.5		$	9.3		$	172.4		$	247.2

Schedule of Identifiable Intangible Assets	The Company’s identifiable intangible assets with finite lives are being amortized over their estimated useful lives and are summarized below:



								December 31,
								2014								2013
		Estimated			Weighted			Gross			Accumulated			Net		Gross		Accumulated		Net
		life in years			average			Carrying			Amortization					Carrying		Amortization
					remaining life in			Amount								Amount
					years

	(Dollars in millions)
	Customer contracts		9 to 17			14.8		$	149.9		$	14.5		$	135.4	$	19.8	$	9.7	$	10.1
	Technology		4 to 12			7			26.7			1.4			25.3		0		0		0
	Trademarks		4 to 7			6.5			5.6			0.3			5.3		0		0		0
	Supply contracts		10			5.2			2.6			1.2			1.4		2.9		1.1		1.8
	Non-compete agreements		12			9.8			1.5			1.2			0.3		1.6		1.3		0.3
	Favorable lease agreements		3			0			0.8			0.8			0		0.8		0.8		0

	Total					13.2		$	187.1		$	19.4		$	167.7	$	25.1	$	12.9	$	12.2

Schedule of Future Amortization Expense	Estimated amortization expense for the next five years is summarized below:


		Estimated
		annual
		amortization
	(Dollars in millions)
	2015		14.9
	2016		14.5
	2017		14.3
	2018		14.3
	2019		14.2

Pensions_and_Postretirement_Be1

Pensions and Post-retirement Benefit Plans (Tables)	12 Months Ended
Pensions and Post-retirement Benefit Plans (Tables)	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost for Pension Plans and Other Benefit Plans	Net periodic pension costs for 2014, 2013 and 2012 were as follows:



		December 31,
		Pension Benefits									Other Benefits
		2014			2013			2012			2014			2013			2012
	(Dollars in millions)
	Components of net periodic benefit cost:
	Service cost	$	2.7		$	3.4		$	3.5		$	0.1		$	0.1		$	0.1
	Interest cost		11.8			10.7			10.7			0.5			0.5			0.5
	Expected return on plan assets		(13.9	)		(12.5	)		(10.7	)		0			0			0
	Amortization of prior service cost		(0.2	)		0.1			0.1			0			0			0
	Amortization of net loss		4			7.6			8.1			0.2			(0.1	)		0
	Amortization of transition asset		0			0			(0.3	)		0			0			0
	Settlements and curtailments		0			0.1			0.3			0			0			0

	Net periodic benefit cost	$	4.4		$	9.4		$	11.7		$	0.4		$	0.5		$	0.6

Schedule of Change in Funded Status of Pension and Post-Retirement Plans	The change in the funded status of the pension and postretirement plans as of December 31, 2014 and December 31, 2013 is as follows:


		December 31,
		Pension Benefits						Other Benefits
		2014			2013			2014			2013
	(Dollars in millions)
	Change in benefit obligation:
	Benefit obligation at beginning of year	$	237.8		$	255.2		$	10.4		$	11.2
	Service cost		2.7			3.4			0.1			0.1
	Interest cost		11.8			10.7			0.5			0.5
	Plan participants’ contributions		0.2			0.2			0			0
	Actuarial losses (gains)		39.4			(18.6	)		(1.1	)		(1.3	)
	Plan amendments		0			(1.5	)		0			0
	Settlements		0			(0.9	)		0			0
	Currency translation		(4.4	)		0.2			0			0
	Benefits paid		(11.8	)		(10.9	)		(0.1	)		(0.1	)

	Benefit obligation at end of year		275.7			237.8			9.8			10.4
	Change in plan assets:
	Fair value of plan assets at beginning of year		205.7			175.6			0			0
	Actual return on plan assets		24			19.2			0			0
	Employer contribution		15.1			22.5			0.1			0.1
	Plan participants’ contributions		0.2			0.2			0			0
	Settlements		0			(0.9	)		0			0
	Currency translation		(3.7	)		0			0			0
	Benefits paid		(11.8	)		(10.9	)		(0.1	)		(0.1	)

	Fair value of plan assets at end of year		229.5			205.7			0			0

	Funded status of the plan	$	(46.2	)	$	(32.1	)	$	(9.8	)	$	(10.4	)

	Amounts recognized in the balance sheet consist of:
	Noncurrent assets	$	0.2		$	0.6		$	0		$	0
	Current liabilities		0.9			0.7			0.7			0.8
	Noncurrent liabilities		45.5			32			9.1			9.6
	Pension plans with benefit obligations in excess of plan assets:
	Benefit obligation	$	237		$	231.9
	Fair value of plan assets		200.2			199.2
	Pension plans with accumulated benefit obligations in excess of plan assets:
	Accumulated benefit obligation	$	230.7		$	225
	Fair value of plan assets		200.2			199.2

Schedule of Projected Benefit Payments	Benefit payments for pension benefits, which are primarily funded by the pension plan assets, and other benefits, which are funded by general corporate assets and reflecting future expected service as appropriate, are expected to be paid as follows:


		Pension Benefits			Other Benefits
	(Dollars in millions)
	2015	$	12.1		$	0.7
	2016		12.4			0.7
	2017		13.3			0.7
	2018		14.3			0.7
	2019		13.8			0.8
	2020 – 2024		78.9			3.1

Schedule of Weighted-Average Assumptions	Weighted-Average Assumptions as of December 31

		December 31,
		Pension Benefits						Other Benefits
		2014			2013			2014			2013
	Discount rate		4.12	%		5.06	%		4.32	%		5.25	%
	Expected return on plan assets		6.31			7.04
	Rate of compensation increase		4			3.13
	Initial medical trend rate								6.95			7.15

Schedule of Weighted Average Asset Allocation for Company's Pension Plans	The weighted average asset allocation for the Company’s pension plans at December 31 by asset category is as follows:

		December 31,
		2014			2013
	Debt securities		71	%		59	%
	Equity securities		26			38
	Other		3			3

			100	%		100	%

Schedule of Pension Plan Assets at Fair Value	The pension assets are all substantially held in pooled or commingled investment vehicles. The following table sets forth by level, the Company’s pension plan assets at fair value, within the fair value hierarchy, as of December 31, 2014 and December 31, 2013:

		As of December 31, 2014
		Quoted prices			Significant			Significant			Total
		in active			observable			unobservable
		markets for			inputs			inputs
		identical assets			(Level 2)			(Level 3)
		(Level 1)
	(Dollars in millions)
	U.S. equity securities	$	17.5		$	10.5		$	0			$ 28.0
	International equity securities		12.7			20			0			32.7
	U.S. debt securities		36.4			92.1			0			128.5
	International debt securities		7.8			26.8			0			34.6
	Real estate and other investments		0			1.9			0			1.9
	Cash and cash equivalents		0			3.8			0			3.8

		$	74.4		$	155.1		$	0			$229.50


		As of December 31, 2013
		Quoted prices			Significant			Significant			Total
		in active			observable			unobservable
		markets for			inputs			inputs
		identical assets			(Level 2)			(Level 3)
		(Level 1)
	(Dollars in millions)
	U.S. equity securities	$	17.8		$	15.9		$	0			$ 33.7
	International equity securities		0			44.3			0			44.3
	U.S. debt securities		24.8			64.7			0			89.5
	International debt securities		7.4			24.9			0			32.3
	Real estate and other investments		0			1.5			0			1.5
	Cash and cash equivalents		0			4.4			0			4.4

		$	50		$	155.7		$	0			$205.70

Schedule of Health Care Cost Trend Rates	A one-percentage-point change in the assumed health care cost trend rate would have the following effects:


		1% Increase			1% Decrease
	(Dollars in millions)
	Increase (decrease) from change in health care cost trend rates:
	Postretirement benefit expense	$	0		$	0
	Postretirement benefit liability		0.2			(0.2	)

Debt_Tables

Debt (Tables)	12 Months Ended
Debt (Tables)	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of Long-Term Debt Instruments	Debt at December 31, 2014 and December 31, 2013 was as follows:


							December 31,
		Weighted			Maturity		2014		2013
		Average
		Interest Rate
	(Dollars in millions, except interest rates)
	Term Loan		3.63%			2019	$	292.5	$	0
	Revolving credit facility		3.63%			2019		204.5	$	0
	Construction and other loans		5.81%			2018		56.5		6.6
	Senior Notes		7⁷/ ⁸%			2019		297		296.5

	Total debt							850.5		303.1
	Less short-term debt and current maturities of long-term debt							43.9		0

	Long-term debt (excluding current portion)						$	806.6	$	303.1

Schedule of Debt Maturities	At December 31, 2014 the aggregate debt maturities for the next five years are as follows:


	(Dollars in millions)
	2015	$	43.9
	2016		36.4
	2017		44.9
	2018		51.3
	2019		677
	Thereafter		0

	Total maturities		853.5
	Future accretion on Senior Notes		(3.0	)

	Total debt	$	850.5

Leases_Tables

Leases (Tables)	12 Months Ended
Leases (Tables)	Dec. 31, 2014
Leases [Abstract]
Future Minimum Commitments for Operating Leases	Future minimum commitments for operating leases having non-cancelable lease terms in excess of one year are as follows:


	(Dollars in millions)
	2015	$	35.6
	2016		30.5
	2017		27.5
	2018		21.2
	2019		7.6
	Thereafter		33.7

	Total	$	156.1

Common_Stock_and_Senior_Conver1

Common Stock and Senior Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2014
Text Block [Abstract]
Schedule of Changes in Senior Convertible Preferred Stock, Common Stock and Treasury Stock	Changes in senior convertible preferred stock, common stock and treasury stock for the three years ended December 31, 2014 are as follows:

		Year Ended December 31,
		2014			2013			2012
	(Shares in thousands)
	Senior Convertible Preferred Stock:
	Balance at beginning and end of year		0			0			0

	Common Stock:
	Balance at beginning of year		21,722			21,585			21,309
	Issued for employee stock plans		216			137			276

	Balance at end of year		21,938			21,722			21,585

	Treasury Stock:
	Balance at beginning of year		(1,390	)		(951	)		(706	)
	Shares repurchased		(53	)		(439	)		(245	)

	Balance at end of year		(1,443	)		(1,390	)		(951	)

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities (Tables)	12 Months Ended
Commitments and Contingent Liabilities (Tables)	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Changes in Accrued Liability for Environmental Matters	The following table reflects changes in the accrued liability for environmental matters, of which $3.3 million and $8.2 million are classified as current liabilities at December 31, 2014 and 2013, respectively:


		Year Ended December 31,
		2014			2013
	(Dollars in millions)
	Balance at beginning of year		$11.90			$14.10
	Expense		0.8			1.8
	Reversal of reserves		(1.5	)		(1.2	)
	Cash expenditures		(3.7	)		(0.9	)
	Acquisition		0.7			0
	Currency translation		(0.4	)		(1.9	)

	Balance at end of year		$7.80			$11.90

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
Selected Quarterly Financial Data (Unaudited) (Tables)	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Financial Data	The following is a summary of the quarterly results of operations for the years ended December 31, 2014 and 2013:



		Year Ended December 31, 2014
		1^stQuarter			2^ndQuarter			3^rdQuarter			4^thQuarter			Fiscal Year
	(Dollars in millions, except per share amounts)
	Statement of operations data:
	Net sales	$	331.4		$	356.8		$	440.1		$	426.7		$	1,555.00
	Operating profit		0.5			13.3			17.3			2.1			33.2
	Income (loss) from continuing operations		(0.1	)		0.8			(4.3	)		(36.4	)		(40.0	)
	Net income (loss)		(0.1	)		0.7			(4.2	)		(35.8	)		(39.4	)
	Net income (loss) attributable to Koppers^(c)		2.2			1.6			(2.7	)		(33.5	)		(32.4	)
	Common stock data:
	Earnings (loss) per common share attributable to Koppers common shareholders:^(a)
	Basic –
	Continuing operations	$	0.11		$	0.08		$	(0.14	)	$	(1.66	)	$	(1.61	)
	Discontinued operations		0			0			0			0.03			0.03

	Earnings (loss) per basic common share	$	0.11		$	0.08		$	(0.14	)	$	(1.63	)	$	(1.58	)

	Diluted –
	Continuing operations	$	0.11		$	0.08		$	(0.14	)	$	(1.66	)	$	(1.61	)
	Discontinued operations		0			0			0			0.03			0.03

	Earnings (loss) per diluted common share	$	0.11		$	0.08		$	(0.14	)	$	(1.63	)	$	(1.58	)

	Dividends declared per common share	$	0.25		$	0.25		$	0.25		$	0.25		$	1
	Price range of common stock:
	High	$	45.92		$	45.51		$	39.45		$	39.88		$	45.92
	Low		35.51			35.53			33.02			22.52			22.52





		Year Ended December 31, 2013
		1^stQuarter			2^ndQuarter			3^rdQuarter			4^thQuarter			Fiscal Year
	(Dollars in millions, except per share amounts)
	Statement of operations data:
	Net sales	$	370.4		$	370.9		$	395.2		$	341.8		$	1,478.30
	Operating profit^(b)		24.9			28.5			39.1			7.8			100.3
	Income from continuing operations		11.4			14.8			19.6			(5.6	)		40.2
	Net income		11.5			14.7			19.5			(5.6	)		40.1
	Net income attributable to Koppers		11			14.4			19.1			(4.1	)		40.4
	Common stock data:
	Earnings (loss) per common share attributable to Koppers common shareholders:^(a)
	Basic –
	Continuing operations	$	0.53		$	0.7		$	0.93		$	(0.20	)	$	1.96
	Discontinued operations		0			(0.01	)		0			0			0

	Earnings per basic common share	$	0.53		$	0.69		$	0.93		$	(0.20	)	$	1.96

	Diluted –
	Continuing operations	$	0.53		$	0.7		$	0.92		$	(0.20	)	$	1.94
	Discontinued operations		0			(0.01	)		0			0			0

	Earnings per diluted common share	$	0.53		$	0.69		$	0.92		$	(0.20	)	$	1.94

	Dividends declared per common share	$	0.25		$	0.25		$	0.25		$	0.25		$	1
	Price range of common stock:
	High	$	45.72		$	46.48		$	42.43		$	49.99		$	49.99
	Low		38.7			37.45			34.69			41.61			34.69



(a)	The cumulative sum of quarterly basic and diluted net income per share amounts may not equal total basic and diluted net income per share amounts for the year due to differences in weighted average and equivalent shares outstanding for each of the periods presented.
(b)	In the fourth quarter of 2013, the Company recorded asset impairment charges totaling $11.9 million primarily consisting of write-downs related to the Company’s coal tar distillation facilities located in Uithoorn, the Netherlands; Tangshan, China; and Follansbee, West Virginia.
(c)	In the fourth quarter of 2014, the Company recorded a $24.3 million income tax charge related to a legal entity reorganization project.

Subsidiary_Guarantor_Informati1

Subsidiary Guarantor Information for Koppers Inc. Senior Notes (Tables)	12 Months Ended
	Dec. 31, 2014
Text Block [Abstract]
Condensed Consolidating Statement of Comprehensive (Loss) Income	Condensed Consolidating Statement of Comprehensive (Loss) Income

	For the Year Ended December 31, 2014



			Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
											Guarantor				Subsidiaries				Adjustments
											Subsidiaries
	(Dollars in millions)
	Net sales		$	0			$	795.9			$	143			$	683.5			$	(67.4	)		$	1,555.00
	Cost of sales including depreciation and amortization			0				724.5				108.8				639				(66.7	)			1,405.60
	Selling, general and administrative			2.2				59.2				17.4				37.4				0				116.2

	Operating profit (loss)			(2.2	)			12.2				16.8				7.1				(0.7	)			33.2
	Other income (expense)			0				0.2				4.7				(0.6	)			(4.3	)			0
	Equity income of subsidiaries			(31.0	)			(15.9	)			(6.4	)			0				(53.3	)			0
	Interest expense			0				36.5				0				6.9				(4.3	)			39.1
	Income taxes			(0.8	)			(9.0	)			30.5				13.4				0				34.1

	Income from continuing operations			(32.4	)			(31.0	)			(15.4	)			(13.8	)			(52.6	)			(40.0	)
	Discontinued operations			0				0				(0.6	)			1.2				0				0.6
	Noncontrolling interests			0				0				0				(7.0	)			0				(7.0	)

	Net loss attributable to Koppers		$	(32.4	)		$	(31.0	)		$	(16.0	)		$	(5.6	)		$	(52.6	)		$	(32.4	)

	Comprehensive loss attributable to Koppers		$	(82.5	)		$	(81.1	)		$	(54.4	)		$	(35.1	)		$	170.6			$	(82.5	)




	Condensed Consolidating Statement of Comprehensive Income

	For the Year Ended December 31, 2013



			Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
											Guarantor				Subsidiaries				Adjustments
											Subsidiaries
	(Dollars in millions)
	Net sales		$	0			$	843.7			$	61.8			$	622.2			$	(49.4	)		$	1,478.30
	Cost of sales including depreciation and amortization			0				745.4				43.5				566.9				(49.5	)			1,306.30
	Selling, general and administrative			1.9				41.5				0.7				27.6				0				71.7

	Operating profit (loss)			(1.9	)			56.8				17.6				27.7				0.1				100.3
	Other income (expense)			0				1.3				4.2				2.1				(4.1	)			3.5
	Equity income of subsidiaries			41.7				17.5				11.4				0				(70.6	)			0
	Interest expense			0				26.7				0				4.2				(4.1	)			26.8
	Income taxes			(0.6	)			7.3				16.4				13.7				0				36.8

	Income from continuing operations			40.4				41.6				16.8				11.9				(70.5	)			40.2
	Discontinued operations			0				0.1				0				(0.2	)			0				(0.1	)
	Noncontrolling interests			0				0				0				(0.3	)			0				(0.3	)

	Net income attributable to Koppers		$	40.4			$	41.7			$	16.8			$	12			$	(70.5	)		$	40.4

	Comprehensive income attributable to Koppers		$	52.3			$	53.5			$	8.4			$	13.8			$	(75.7	)		$	52.3


	Condensed Consolidating Statement of Comprehensive Income

	For the Year Ended December 31, 2012



		Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
										Guarantor				Subsidiaries				Adjustments
										Subsidiaries
(Dollars in millions)
Net sales		$	0			$	893.2			$	97.5			$	638.4			$	(74.1	)		$	1,555.00
Cost of sales including depreciation and amortization			0				786.6				78				562				(73.8	)			1,352.80
Selling, general and administrative			1.6				45.1				2.1				26.8				0				75.6

Operating profit (loss)			(1.6	)			61.5				17.4				49.6				(0.3	)			126.6
Other income (expense)			0				0.4				6.1				0.6				(5.2	)			1.9
Equity income of subsidiaries			66.6				40.8				28.8				0.1				(136.3	)			0
Interest expense			0				27.4				0				5.8				(5.3	)			27.9
Income taxes			(0.6	)			8.7				12.5				12.7				0				33.3

Income from continuing operations			65.6				66.6				39.8				31.8				(136.5	)			67.3
Discontinued operations			0				0				0				(0.1	)			0				(0.1	)
Noncontrolling interests			0				0				0				1.6				0				1.6

Net income attributable to Koppers		$	65.6			$	66.6			$	39.8			$	30.1			$	(136.5	)		$	65.6

Comprehensive income attributable to Koppers		$	73.7			$	74.8			$	44			$	32.4			$	(151.2	)		$	73.7

Condensed Consolidating Balance Sheet
	Condensed Consolidating Balance Sheet

	December 31, 2014



			Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
											Guarantor				Subsidiaries				Adjustments
											Subsidiaries
	(Dollars in millions)
	ASSETS
	Cash and cash equivalents		$	0			$	0			$	0.9			$	50.2			$	0			$	51.1
	Receivables, net			0				75.7				20				103				0				198.7
	Affiliated receivables			0.8				4.5				9.3				1.3				(15.9	)			0
	Inventories, net			0				108.8				30.8				102.6				(1.0	)			241.2
	Deferred tax assets			0				8				1				1.5				0				10.5
	Other current assets			0				3				2.2				34.6				0				39.8

	Total current assets			0.8				200				64.2				293.2				(16.9	)			541.3
	Equity investments			74.5				767.2				213.5				3.6				(1,053.8	)			5
	Property, plant and equipment, net			0				121.2				43.1				135.4				0				299.7
	Goodwill			0				39.8				149.9				57.5				0				247.2
	Intangible assets, net			0				2.2				128.1				37.4				0				167.7
	Deferred tax assets			0				(1.0	)			1.1				7.7				0				7.8
	Affiliated loan receivables			0				40.5				212				40.9				(293.4	)			0
	Other noncurrent assets			0				19.1				5.2				0.9				0				25.2

	Total assets		$	75.3			$	1,189.00			$	817.1			$	576.6			($	1,364.10	)		$	1,293.90

	LIABILITIES AND EQUITY
	Accounts payable		$	0.1			$	60.9			$	9			$	50.6			$	0			$	120.6
	Affiliated payables			0				13.2				2.7				13.5				(29.4	)			0
	Accrued liabilities			5.2				37.9				29.5				55				0				127.6
	Short-term debt and current portion of long-term debt			0				30				0				13.9				0				43.9

	Total current liabilities			5.3				142				41.2				133				(29.4	)			292.1
	Long-term debt			0				764				0				42.6				0				806.6
	Affiliated debt			0				145.5				35.9				112				(293.4	)			0
	Other long-term liabilities			0				68.6				7.7				35				0				111.3

	Total liabilities			5.3				1,120.10				84.8				322.6				(322.8	)			1,210.00
	Koppers shareholders’ equity			70				68.9				732.3				240.1				(1,041.3	)			70
	Noncontrolling interests			0				0				0				13.9				0				13.9

	Total liabilities and equity		$	75.3			$	1,189.00			$	817.1			$	576.6			($	1,364.10	)		$	1,293.90




	Condensed Consolidating Balance Sheet

	December 31, 2013



			Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
											Guarantor				Subsidiaries				Adjustments
											Subsidiaries
	(Dollars in millions)
	ASSETS
	Cash and cash equivalents		$	0			$	29.9			$	0.1			$	52.2			$	0			$	82.2
	Receivables, net			0				75.6				9.3				82				0				166.9
	Affiliated receivables			0.2				1.1				3.9				2.3				(7.5	)			0
Inventories, net			0				86.1				0				82.9				(0.2	)			168.8
Deferred tax assets			0				7.9				1.5				0.6				0				10
Other current assets			0				7.3				0.6				37.3				0				45.2

Total current assets			0.2				207.9				15.4				257.3				(7.7	)			473.1
Equity investments			174.7				333.5				182.9				4.6				(689.1	)			6.6
Property, plant and equipment, net			0				112.2				0				84.8				0				197
Goodwill			0				39.8				0				32.9				0				72.7
Deferred tax assets			0				2.4				(1.4	)			8.3				0				9.3
Affiliated loan receivables			0				8.5				123.8				40.9				(173.2	)			0
Other noncurrent assets			0				15				0				11.2				0				26.2

Total assets		$	174.9			$	719.3			$	320.7			$	440			$	(870.0	)		$	784.9

LIABILITIES AND EQUITY
Accounts payable		$	0			$	48.3			$	6.7			$	52.6			$	0			$	107.6
Affiliated payables			0				1.9				4				8.6				(14.5	)			0
Accrued liabilities			5.1				27.8				0.5				54.1				0				87.5

Total current liabilities			5.1				78				11.2				115.3				(14.5	)			195.1
Long-term debt			0				296.5				0				6.6				0				303.1
Affiliated debt			0				109.5				8.5				55.2				(173.2	)			0
Other long-term liabilities			0				67.6				2.5				26.8				0				96.9

Total liabilities			5.1				551.6				22.2				203.9				(187.7	)			595.1
Koppers shareholders’ equity			169.8				167.7				298.5				216.1				(682.3	)			169.8
Noncontrolling interests			0				0				0				20				0				20

Total liabilities and equity		$	174.9			$	719.3			$	320.7			$	440			$	(870.0	)		$	784.9

Condensed Consolidating Statement of Cash Flows

	Condensed Consolidating Statement of Cash Flows

	For the Year Ended December 31, 2014



			Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
											Guarantor				Subsidiaries				Adjustments
											Subsidiaries
	(Dollars in millions)
	Cash provided by (used in) operating activities		$	21.8			$	23.8			$	34.7			$	9.5			$	(54.3	)		$	35.5
	Cash provided by (used in) investing activities:
	Capital expenditures and acquisitions			0				(518.5	)			(16.7	)			(59.9	)			14.8				(580.3	)
	(Loans to) repayments from affiliates			0				(32.2	)			(38.9	)			0				71.1				0
	Net cash proceeds from divestitures and asset sales			0				0.1				0.1				0.1				0				0.3

	Net cash used in investing activities			0				(550.6	)			(55.5	)			(59.8	)			85.9				(580.0	)
	Cash provided by (used in) financing activities:
	Borrowings (repayments) of long-term debt			0				497				0				50.5				0				547.5
	Borrowings (repayments) of affiliated debt			0				35.8				27.6				7.7				(71.1	)			0
	Deferred financing costs			0				(11.1	)			0				0				0				(11.1	)
	Other financing activities			0				0				0				1.4				0				1.4
	Dividends paid			(20.5	)			(23.6	)			(6.1	)			(24.5	)			54.3				(20.4	)
	Stock issued (repurchased)			(1.3	)			0				0				14.8				(14.8	)			(1.3	)

	Net cash provided by (used in) financing activities			(21.8	)			498.1				21.5				49.9				(31.6	)			516.1
	Effect of exchange rates on cash			0				(1.2	)			1				(2.5	)			0				(2.7	)

	Net increase (decrease) in cash and cash equivalents			0				(29.9	)			1.7				(2.9	)			0				(31.1	)
	Cash and cash equivalents at beginning of year			0				29.9				0.1				52.2				0				82.2

	Cash and cash equivalents at end of period		$	0			$	0			$	1.8			$	49.3			$	0			$	51.1


	Condensed Consolidating Statement of Cash Flows

	For the Year Ended December 31, 2013



			Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
											Guarantor				Subsidiaries				Adjustments
											Subsidiaries
	(Dollars in millions)
	Cash provided by (used in) operating activities		$	37.8			$	278.7			$	130.1			$	47.6			$	(376.6	)		$	117.6
	Cash provided by (used in) investing activities:
	Capital expenditures and acquisitions			0				(23.3	)			0				(51.9	)			0				(75.2	)
	(Loans to) repayments from affiliates			0				(0.8	)			193.2				(1.7	)			(190.7	)			0
	Net cash proceeds (payments) from divestitures and asset sales			0				1.3				0				1.6				0				2.9

	Net cash used in investing activities			0				(22.8	)			193.2				(52.0	)			(190.7	)			(72.3	)
	Cash provided by (used in) financing activities:
	Borrowings (repayments) of long-term debt			0				0				0				6.6				0				6.6
	Borrowings of affiliated long-term debt			0				(191.5	)			0.8				0				190.7				0
	Deferred financing costs			0				(1.3	)			0				0				0				(1.3	)
	Dividends paid			(20.5	)			(38.5	)			(324.0	)			(14.7	)			376.6				(21.1	)
	Stock issued and repurchased			(17.3	)			0				0				0				0				(17.3	)
	Other financing receipts			0				0.5				0				2.3				0				2.8

	Net cash provided by (used in) financing activities			(37.8	)			(230.8	)			(323.2	)			(5.8	)			567.3				(30.3	)
	Effect of exchange rates on cash			0				0				0				0.5				0				0.5

Net increase in cash and cash equivalents			0				25.1				0.1				(9.7	)			0				15.5
Cash and cash equivalents at beginning of year			0				4.8				0				61.9				0				66.7

Cash and cash equivalents at end of period		$	0			$	29.9			$	0.1			$	52.2			$	0			$	82.2




Condensed Consolidating Statement of Cash Flows

For the Year Ended December 31, 2012



		Parent				Koppers Inc.				Domestic				Non-Guarantor				Consolidating				Consolidated
										Guarantor				Subsidiaries				Adjustments
										Subsidiaries
(Dollars in millions)
Cash provided by (used in) operating activities		$	26.1			$	44.6			$	8.7			$	30.9			$	(32.5	)		$	77.8
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions			0				(21.3	)			0				(21.6	)			0				(42.9	)
Loan repayment by related party			0				0				0				2.2				0				2.2
(Loans to) repayments from affiliates			0				0.3				(8.4	)			(2.7	)			10.8				0
Net cash proceeds (payments) from divestitures and asset sales			0				0.4				0				0.4				0				0.8

Net cash used in investing activities			0				(20.6	)			(8.4	)			(21.7	)			10.8				(39.9	)
Cash provided by (used in) financing activities:
Repayments of long-term debt			0				(6.4	)			0				0				0				(6.4	)
Borrowings of affiliated long-term debt			0				13.3				(0.3	)			(2.2	)			(10.8	)			0
Deferred financing costs			0				(0.1	)			0				0				0				(0.1	)
Dividends paid			(19.5	)			(27.6	)			0				(4.9	)			32.5				(19.5	)
Stock issued and repurchased			(6.6	)			0				0				0				0				(6.6	)
Other financing receipts			0				1.6				0				3.7				0				5.3

Net cash provided by (used in) financing activities			(26.1	)			(19.2	)			(0.3	)			(3.4	)			21.7				(27.3	)
Effect of exchange rates on cash			0				0				0				2				0				2

Net increase in cash and cash equivalents			0				4.8				0				7.8				0				12.6
Cash and cash equivalents at beginning of year			0				0				0				54.1				0				54.1

Cash and cash equivalents at end of period		$	0			$	4.8			$	0			$	61.9			$	0			$	66.7

Description_of_Business_Additi

Description of Business - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
	Segment
Collaboration Arrangement Disclosure [Abstract]
Number of operating segments	3

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary Of Significant Accounting Policies [Line Items]
Foreign currency transaction losses									$600,000	($500,000)	($1,700,000)
Period for payment of approval basis sale									30 days
Net sales	426,700,000	440,100,000	356,800,000	331,400,000	341,800,000	395,200,000	370,900,000	370,400,000	1,555,000,000	1,478,300,000	1,555,000,000
Research and development costs									3,100,000	2,400,000	2,300,000
Percentage of LIFO inventory	61.00%				62.00%				61.00%	62.00%
Impairment of goodwill	0				0
Prepaid expenses	20,600,000				17,300,000				20,600,000	17,300,000
Untreated Crosstie Sales [Member]
Summary Of Significant Accounting Policies [Line Items]
Net sales									$93,400,000	$108,300,000	$109,000,000
Minimum [Member] \| Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives									10 years
Minimum [Member] \| Machinery and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives									3 years
Maximum [Member] \| Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives									20 years
Maximum [Member] \| Machinery and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives									10 years

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Summary of Self-lnsured Liabilities (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Self-insured liabilities at beginning of year	$8.40	$7.60
Expense	2.4	2.5
Reversal of self-insured liabilities	-0.8	-0.4
Cash expenditures	-1.8	-1.3
Self-insured liabilities at end of year	$8.20	$8.40

Summary_of_Significant_Account5

Summary of Significant Accounting Policies - Summary of Asset Retirement Obligation Liabilities (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligation at beginning of year	$23.20	$21.50
Accretion expense	2.3	1.2
Revision in estimated cash flows	10.3	6.7
Cash expenditures	-4.6	-5.6
Currency translation	-0.7	-0.6
Asset retirement obligation at end of year	$30.50	$23.20

Summary_of_Significant_Account6

Summary of Significant Accounting Policies - Summary of Changes to Deferred Revenue (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Revenue Disclosure [Abstract]
Deferred revenue at beginning of year	$3.20	$3.90
Revenue earned	-0.7	-0.7
Deferred revenue at end of year	$2.50	$3.20

Plant_Closures_and_Discontinue2

Plant Closures and Discontinued Operations - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Costs related to closure		$13
Impairment charges	6.9	4.7	11.9	0.6
Carbon Materials and Chemicals [Member]
Restructuring Cost and Reserve [Line Items]
Impairment charges		$4.70	$11.90
Carbon Materials and Chemicals [Member] \| Discontinued Operations [Member]
Restructuring Cost and Reserve [Line Items]
Future completion period, closure		2015

Plant_Closures_and_Discontinue3

Plant Closures and Discontinued Operations - Summary of Restructuring Activities and Related Reserves (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Reserve, Beginning Balance	$9	$13.30
Accrual	13.1
Reversal of accrued charges	-2	-0.4
Cash paid	-11	-2.2
Currency translation	-1	-1.7
Reserve, Ending Balance	8.1	9
Severance and Employee Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Reserve, Beginning Balance	0.1	0.2
Accrual	9.8
Reversal of accrued charges	0	-0.1
Cash paid	-9.7	0
Currency translation	-0.2	0
Reserve, Ending Balance	0	0.1
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Reserve, Beginning Balance	5.6	6.7
Accrual	0
Reversal of accrued charges	-1.1	0
Cash paid	0	-0.1
Currency translation	-0.4	-1
Reserve, Ending Balance	4.1	5.6
Site Demolition [Member]
Restructuring Cost and Reserve [Line Items]
Reserve, Beginning Balance	3.3	6.3
Accrual	3.2
Reversal of accrued charges	-0.9	-0.3
Cash paid	-1.3	-2
Currency translation	-0.4	-0.7
Reserve, Ending Balance	3.9	3.3
Other [Member]
Restructuring Cost and Reserve [Line Items]
Reserve, Beginning Balance	0	0.1
Accrual	0.1
Reversal of accrued charges	0	0
Cash paid	0	-0.1
Currency translation	0	0
Reserve, Ending Balance	$0.10	$0

Business_Acquisitions_Addition

Business Acquisitions - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended			0 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 19, 2012	Jan. 20, 2014	Aug. 15, 2014
Business Acquisition [Line Items]
Business acquisition cash payment									$496,500,000	$2,300,000	$14,000,000
Goodwill	247,200,000				72,700,000				247,200,000	72,700,000	75,600,000
Business acquisition, net income from continuing operations									-33,000,000	40,500,000	65,700,000
Revenues from external customers	426,700,000	440,100,000	356,800,000	331,400,000	341,800,000	395,200,000	370,900,000	370,400,000	1,555,000,000	1,478,300,000	1,555,000,000
Operating profit	2,100,000	17,300,000	13,300,000	500,000	7,800,000	39,100,000	28,500,000	24,900,000	33,200,000	100,300,000	126,600,000
Railroad and Utility Products and Services [Member]
Business Acquisition [Line Items]
Revenues from external customers									597,800,000	572,200,000	555,300,000
Performance Chemicals [Member]
Business Acquisition [Line Items]
Revenues from external customers									123,500,000	0	0
Western Poles [Member]
Business Acquisition [Line Items]
Business acquisition cash payment												13,800,000
Amount payable assuming certain sales contracts												4,900,000
Acquisition payment term												36 months
Tolko Industries Ltd [Member]
Business Acquisition [Line Items]
Business acquisition purchase price													29,800,000
Acquired assets, inventory													16,000,000
Acquired assets, plant and equipment													3,600,000
Goodwill recognized	150,000,000								150,000,000
Tolko Industries Ltd [Member] \| Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets, primarily customer relationships													7,400,000
Customer contracts, amortization period													12 years
Tolko Industries Ltd [Member] \| Railroad and Utility Products and Services [Member]
Business Acquisition [Line Items]
Goodwill	3,400,000								3,400,000				1,800,000
Tolko Industries Ltd [Member] \| Performance Chemicals [Member]
Business Acquisition [Line Items]
Goodwill	175,400,000								175,400,000
Osmose Holdings, Inc. [Member]
Business Acquisition [Line Items]
Business acquisition cash payment														494,100,000
Acquired assets, inventory	51,900,000								51,900,000
Acquired assets, plant and equipment	57,900,000								57,900,000
Estimated cash acquired	27,200,000								27,200,000					27,200,000
Acquisition-related costs reported in selling, general and administrative expenses									5,900,000	300,000
Business acquisition, revenues										391,500,000
Business acquisition, net income from continuing operations										19,300,000
Revenues from external customers									144,300,000
Operating profit									5,200,000
Recognized value of amortization of finished goods inventory									3,500,000
Osmose Holdings, Inc. [Member] \| Senior Secured Credit Facilities [Member]
Business Acquisition [Line Items]
Revolving credit facility														500,000,000
Osmose Holdings, Inc. [Member] \| Term Loan Facility [Member]
Business Acquisition [Line Items]
Revolving credit facility														$300,000,000

Business_Acquisitions_Schedule

Business Acquisitions - Schedule of Company's Preliminary Fair Value Estimates for Osmose Entities (Detail) (Osmose Holdings, Inc. [Member], USD $)	Dec. 31, 2014	Aug. 15, 2014
In Millions, unless otherwise specified	Dec. 31, 2014	Aug. 15, 2014
Osmose Holdings, Inc. [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	$27.20	$27.20
Accounts receivable, net	60.3
Inventories, net	51.9
Other current assets	3.3
Property, plant and equipment	57.9
Goodwill	178.8
Intangible assets	158.9
Other assets	10.3
Total assets acquired	548.6
Accounts payable	21.2
Accrued liabilities	18.1
Other liabilities	15.2
Total liabilities assumed	54.5
Net assets acquired	$494.10

Business_Acquisitions_Summary_

Business Acquisitions - Summary of Company's Revenue And Net Income From Continuing Operations (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Business Combination Increase Decrease To Reflect Liabilities Acquired At Fair Value [Abstract]
Revenue	$1,819.60	$1,864.10
(Loss) income from continuing operations attributable to Koppers	($13)	$41.50

Fair_Value_Measurements_Schedu

Fair Value Measurements - Schedule of Company's Financial Instruments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value [Member]
Financial assets:
Cash and cash equivalents, including restricted cash	$51.10	$82.20
Investments and other assets	1.5	1.4
Financial liabilities:
Long-term debt (including current portion)	862.1	331.2
Carrying Value [Member]
Financial assets:
Cash and cash equivalents, including restricted cash	51.1	82.2
Investments and other assets	1.5	1.4
Financial liabilities:
Long-term debt (including current portion)	$850.50	$303.10

Earnings_per_Common_Share_Sche

Earnings per Common Share - Schedule of Computation of Basic and Diluted Earnings per Common Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net (loss) income attributable to Koppers	($33.50)	($2.70)	$1.60	$2.20	($4.10)	$19.10	$14.40	$11	($32.40)	$40.40	$65.60
Less: discontinued operations									0.6	-0.1	-0.1
(Loss) income from continuing operations attributable to Koppers									($33)	$40.50	$65.70
Weighted average common shares outstanding:
Basic									20,463	20,575	20,681
Effect of dilutive securities									0	240	246
Diluted									20,463	20,815	20,927
(Loss) earnings per common share - continuing operations:
Basic (loss) earnings per common share	($1.66)	($0.14)	$0.08	$0.11	($0.20)	$0.93	$0.70	$0.53	($1.61)	$1.96	$3.18
Diluted (loss) earnings per common share	($1.66)	($0.14)	$0.08	$0.11	($0.20)	$0.92	$0.70	$0.53	($1.61)	$1.94	$3.14
Other data:
Antidilutive securities excluded from computation of diluted earnings per common share									362	240	194

Stockbased_Compensation_Additi

Stock-based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Intrinsic value of stock options exercised	$0.30	$0	$2
Future compensation expense related to non-vested stock-based compensation arrangements	$3.60
Future compensation expense, weighted-average expected period of recognition in months	21 months
Restricted Stock Units (RSUs) [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Stock options, vesting period	3 years
Restricted Stock Units (RSUs) [Member] \| Board of Directors [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Stock options, vesting period	1 year
Employee Stock Option [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Stock options, term in years	10 years
Performance Stock Units [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Stock options, vesting period	3 years
Vesting performance stock units if minimum performance criteria are not achieved	0
Performance Stock Units [Member] \| Minimum [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of target award earned by participants	0.00%
Performance Stock Units [Member] \| Maximum [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of target award earned by participants	150.00%

Stockbased_Compensation_Summar

Stock-based Compensation - Summary of Performance Stock Units (Detail)	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	429,286	468,820
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	280,380	319,984
Minimum Shares [Member] \| 2012 - 2014 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	0
Minimum Shares [Member] \| 2013 - 2015 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	0
Minimum Shares [Member] \| 2014 - 2016 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	0
Target Shares [Member] \| 2012 - 2014 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	87,039
Target Shares [Member] \| 2013 - 2015 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	85,207
Target Shares [Member] \| 2014 - 2016 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	102,149
Maximum Shares [Member] \| 2012 - 2014 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	130,559
Maximum Shares [Member] \| 2013 - 2015 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	127,811
Maximum Shares [Member] \| 2014 - 2016 [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding	153,224

Stockbased_Compensation_Summar1

Stock-based Compensation - Summary of Status and Activity of Non-Vested Stock Awards (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested, Beginning Balance	468,820
Granted	208,373
Credited from dividends	12,238
Vested	-223,232
Forfeited	-36,913
Non-vested, Ending Balance	429,286
Beginning Balance, Non-vested, Weighted Average Grant Date Fair Value per Unit	$40.30
Granted, Weighted Average Grant Date Fair Value per Unit	$37.92
Credited from dividends, Weighted Average Grant Date Fair Value per Unit	$38.52
Vested, Weighted Average Grant Date Fair Value per Unit	$40
Forfeited, Weighted Average Grant Date Fair Value per Unit	$39.51
Ending Balance, Non-vested, Weighted Average Grant Date Fair Value per Unit	$39.31
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested, Beginning Balance	148,836
Granted	99,867
Credited from dividends	3,813
Vested	-90,915
Forfeited	-12,695
Non-vested, Ending Balance	148,906
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested, Beginning Balance	319,984
Granted	108,506
Credited from dividends	8,425
Vested	-132,317
Forfeited	-24,218
Non-vested, Ending Balance	280,380

Stockbased_Compensation_Stock_

Stock-based Compensation - Stock Options Fair Value Assumptions (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014
February 2014 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date price per share of option award	$37.93
Expected dividend yield per share	2.75%
Expected life in years	6 years 6 months
Expected volatility	52.14%
Risk-free interest rate	1.98%
Grant date fair value per share of option awards	$15.26
February 2013 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date price per share of option award	$42.76
Expected dividend yield per share	2.75%
Expected life in years	6 years 6 months
Expected volatility	53.77%
Risk-free interest rate	1.29%
Grant date fair value per share of option awards	$17.28
February 2012 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date price per share of option award	$38.21
Expected dividend yield per share	2.75%
Expected life in years	6 years 6 months
Expected volatility	55.06%
Risk-free interest rate	1.34%
Grant date fair value per share of option awards	$15.82

Stockbased_Compensation_Summar2

Stock-based Compensation - Summary of Status and Activity of Stock Options (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options, Outstanding at December 31, 2013	421,080
Options, Granted	106,658
Options, Exercised	-26,349
Options, Expired	-17,870
Options, Forfeited	-34,707
Options, Outstanding at December 31, 2014	448,812
Options, Exercisable at December 31, 2014	276,824
Weighted Average Exercise Price per Option, Outstanding at December 31, 2013	$35.96
Weighted Average Exercise Price per Option, Granted	$37.93
Weighted Average Exercise Price per Option, Exercised	$25.51
Weighted Average Exercise Price per Option, Expired	$40.14
Weighted Average Exercise Price per Option, Forfeited	$39.75
Weighted Average Exercise Price per Option, Outstanding at December 31, 2014	$36.58
Weighted Average Exercise Price per Option, Exercisable at December 31, 2014	$34.71
Weighted Average Remaining Contractual Term, Outstanding at December 31, 2014	5 years 11 months 16 days
Weighted Average Remaining Contractual Term, Exercisable at December 31, 2014	4 years 6 months 15 days
Aggregate Intrinsic Value, Outstanding at December 31, 2014	$0.20
Aggregate Intrinsic Value, Exercisable at December 31, 2014	$0.20

Stockbased_Compensation_Schedu

Stock-based Compensation - Schedule of Stock-Based Compensation Expense Recognized and Cash Received from Exercise of Stock Options (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock-based compensation expense recognized:
Selling, general and administrative expenses	$4.70	$4.30	$6.90
Less related income tax benefit	1.9	1.7	2.8
Decrease in net income attributable to Koppers	2.8	2.6	4.1
Cash received from the exercise of stock options	$0.70	$0.20	$1.60

Segment_Information_Additional

Segment Information - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Segment	Dec. 31, 2013	Dec. 31, 2012
Segment Information [Line Items]
Number of reportable segments									3
Revenues	$426.70	$440.10	$356.80	$331.40	$341.80	$395.20	$370.90	$370.40	$1,555	$1,478.30	$1,555
Non-U.S. Countries [Member]
Segment Information [Line Items]
Revenues									$722	$695.80	$727.40

Segment_Information_Summary_of

Segment Information - Summary of Results of Segment Operations (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue from External Customer [Line Items]
Intersegment revenues	$426.70	$440.10	$356.80	$331.40	$341.80	$395.20	$370.90	$370.40	$1,555	$1,478.30	$1,555
Revenues from external customers:
Revenues from external customers	426.7	440.1	356.8	331.4	341.8	395.2	370.9	370.4	1,555	1,478.30	1,555
Intersegment revenues:
Intersegment revenues	426.7	440.1	356.8	331.4	341.8	395.2	370.9	370.4	1,555	1,478.30	1,555
Depreciation and amortization:
Depreciation and amortization expense									44	29.7	27.6
Operating profit:
Operating profit (loss)	2.1	17.3	13.3	0.5	7.8	39.1	28.5	24.9	33.2	100.3	126.6
Capital expenditures (including acquisitions):
Capital expenditures (including acquisitions)									580	75.2	42.9
Carbon Materials and Chemicals [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									833.7	906.1	999.7
Revenues from external customers:
Revenues from external customers									833.7	906.1	999.7
Intersegment revenues:
Intersegment revenues									833.7	906.1	999.7
Railroad and Utility Products and Services [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									597.8	572.2	555.3
Revenues from external customers:
Revenues from external customers									597.8	572.2	555.3
Intersegment revenues:
Intersegment revenues									597.8	572.2	555.3
Performance Chemicals [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									123.5	0	0
Revenues from external customers:
Revenues from external customers									123.5	0	0
Intersegment revenues:
Intersegment revenues									123.5	0	0
Operating Segments [Member] \| Carbon Materials and Chemicals [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									833.7	906.1	999.7
Revenues from external customers:
Revenues from external customers									833.7	906.1	999.7
Intersegment revenues:
Intersegment revenues									833.7	906.1	999.7
Depreciation and amortization:
Depreciation and amortization expense									25	18.2	16.9
Operating profit:
Operating profit (loss)									-5.3	43.9	83.1
Capital expenditures (including acquisitions):
Capital expenditures (including acquisitions)									63.7	58	17.3
Operating Segments [Member] \| Railroad and Utility Products and Services [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									597.8	572.2	555.3
Revenues from external customers:
Revenues from external customers									597.8	572.2	555.3
Intersegment revenues:
Intersegment revenues									597.8	572.2	555.3
Depreciation and amortization:
Depreciation and amortization expense									11.9	11.5	10.7
Operating profit:
Operating profit (loss)									53.6	58.3	45.1
Capital expenditures (including acquisitions):
Capital expenditures (including acquisitions)									44.5	15.9	25
Operating Segments [Member] \| Performance Chemicals [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									123.5	0	0
Revenues from external customers:
Revenues from external customers									123.5	0	0
Intersegment revenues:
Intersegment revenues									123.5	0	0
Depreciation and amortization:
Depreciation and amortization expense									7.1	0	0
Operating profit:
Operating profit (loss)									1.6	0	0
Capital expenditures (including acquisitions):
Capital expenditures (including acquisitions)									471.1	0	0
Intersegment [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									87.8	94.2	106.5
Revenues from external customers:
Revenues from external customers									87.8	94.2	106.5
Intersegment revenues:
Intersegment revenues									87.8	94.2	106.5
Intersegment [Member] \| Carbon Materials and Chemicals [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									84.8	94.2	106.5
Revenues from external customers:
Revenues from external customers									84.8	94.2	106.5
Intersegment revenues:
Intersegment revenues									84.8	94.2	106.5
Intersegment [Member] \| Performance Chemicals [Member]
Revenue from External Customer [Line Items]
Intersegment revenues									3	0	0
Revenues from external customers:
Revenues from external customers									3	0	0
Intersegment revenues:
Intersegment revenues									3	0	0
Corporate, Non-Segment [Member]
Operating profit:
Operating profit (loss)									-16.7	-1.9	-1.6
Capital expenditures (including acquisitions):
Capital expenditures (including acquisitions)									$0.70	$1.30	$0.60

Segment_Information_Summary_of1

Segment Information - Summary of Results of Segment Operations (Parenthetical) (Detail) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue from External Customer [Line Items]
Impairment charges	$6.90	$4.70	$11.90	$0.60
Carbon Materials and Chemicals [Member]
Revenue from External Customer [Line Items]
Impairment charges		4.7	11.9
Railroad and Utility Products and Services [Member]
Revenue from External Customer [Line Items]
Impairment charges				$0.60

Segment_Information_Summary_of2

Segment Information - Summary of Tangible and Intangible Assets by Segments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets:
Cash and cash equivalents	$51.10	$82.20	$66.70	$54.10
Income tax receivable	0	9
Deferred taxes	58.4	51.5
Deferred financing costs	14.5	7.2
Property, plant and equipment, net	299.7	197
Segment assets	1,293.90	784.9
Goodwill:
Goodwill	247.2	72.7	75.6
Operating Segments [Member]
Assets:
Segment assets	1,258.80	714.8
Corporate, Non-Segment [Member]
Assets:
Cash and cash equivalents	0	30
Income tax receivable	0	9
Deferred taxes	10	13.3
Deferred financing costs	14.5	7.2
Property, plant and equipment, net	3.9	3.8
Deferred charges	1.6	2.6
Other	5.1	4.2
Carbon Materials and Chemicals [Member] \| Operating Segments [Member]
Assets:
Segment assets	514.6	535.5
Goodwill:
Goodwill	65.5	68
Railroad and Utility Products and Services [Member] \| Operating Segments [Member]
Assets:
Segment assets	275.2	179.3
Goodwill:
Goodwill	9.3	4.7
Performance Chemicals [Member] \| Operating Segments [Member]
Assets:
Segment assets	469	0
Goodwill:
Goodwill	$172.40	$0

Segment_Information_Schedule_o

Segment Information - Schedule of Revenues and Long-Lived Assets by Geographic Area (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Information [Line Items]
Revenue from external customers	$426.70	$440.10	$356.80	$331.40	$341.80	$395.20	$370.90	$370.40	$1,555	$1,478.30	$1,555
Long-lived assets	744.9				302.5				744.9	302.5	271.6
United States [Member]
Segment Information [Line Items]
Revenue from external customers									833	782.5	827.6
Long-lived assets	537.1				169.1				537.1	169.1	162.9
Australia [Member]
Segment Information [Line Items]
Revenue from external customers									349	348.3	318.9
Long-lived assets	160.3				100.6				160.3	100.6	72.4
Europe [Member]
Segment Information [Line Items]
Revenue from external customers									201.1	225.1	247.8
Long-lived assets	47.5				32.8				47.5	32.8	36.3
Other Countries [Member]
Segment Information [Line Items]
Revenue from external customers									171.9	122.4	160.7
Long-lived assets	$0				$0				$0	$0	$0

Segment_Information_Schedule_o1

Segment Information - Schedule of Segment Revenues for Significant Product Lines (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Information [Line Items]
Net sales	$426.70	$440.10	$356.80	$331.40	$341.80	$395.20	$370.90	$370.40	$1,555	$1,478.30	$1,555
Carbon Materials and Chemicals [Member]
Segment Information [Line Items]
Net sales									833.7	906.1	999.7
Carbon Materials and Chemicals [Member] \| Carbon Pitch [Member]
Segment Information [Line Items]
Net sales									330.2	384.7	442.4
Carbon Materials and Chemicals [Member] \| Creosote and Carbon Black Feedstock [Member]
Segment Information [Line Items]
Net sales									213.7	228.2	233.8
Carbon Materials and Chemicals [Member] \| Phthalic Anhydride [Member]
Segment Information [Line Items]
Net sales									91.4	98.6	120
Carbon Materials and Chemicals [Member] \| Naphthalene [Member]
Segment Information [Line Items]
Net sales									73.5	64.5	60.3
Carbon Materials and Chemicals [Member] \| Other Products [Member]
Segment Information [Line Items]
Net sales									124.9	130.1	143.2
Railroad and Utility Products and Services [Member]
Segment Information [Line Items]
Net sales									597.8	572.2	555.3
Railroad and Utility Products and Services [Member] \| Other Products [Member]
Segment Information [Line Items]
Net sales									66.3	35.9	30.3
Railroad and Utility Products and Services [Member] \| Railroad Crossties [Member]
Segment Information [Line Items]
Net sales									342.2	331.1	341.1
Railroad and Utility Products and Services [Member] \| Utility Poles [Member]
Segment Information [Line Items]
Net sales									96.1	119.3	101.3
Railroad and Utility Products and Services [Member] \| Creosote [Member]
Segment Information [Line Items]
Net sales									51.2	61.4	57
Railroad and Utility Products and Services [Member] \| Rail Joint Bars [Member]
Segment Information [Line Items]
Net sales									27.2	24.5	25.6
Railroad and Utility Products and Services [Member] \| Railroad Infrastructure Services [Member]
Segment Information [Line Items]
Net sales									14.8	0	0
Performance Chemicals [Member]
Segment Information [Line Items]
Net sales									123.5	0	0
Performance Chemicals [Member] \| Other Products [Member]
Segment Information [Line Items]
Net sales									16.5	0	0
Performance Chemicals [Member] \| Wood Preservative Products [Member]
Segment Information [Line Items]
Net sales									$107	$0	$0

Income_Taxes_Summary_of_Income

Income Taxes - Summary of Income Tax Provision (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current:
Federal	$17.50	$3.50	$15.70
State	0.3	0.6	1.3
Foreign	14.6	14	8.6
Total current tax provision	32.4	18.1	25.6
Deferred:
Federal	3.1	16.4	4.9
State	0	2.5	-1.2
Foreign	-1.4	-0.2	4
Total deferred tax provision (benefit)	1.7	18.7	7.7
Total income tax provision	$34.10	$36.80	$33.30

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Income before income taxes	($1.50)	$24.60	$42.60
Income tax benefit relating to copper swap contracts	-2.6	0	0
Income tax (benefit) provision relating to unfunded status of employee post-retirement benefit plans	-8.1	13.5	2.2
Income tax benefit related to restricted stock and stock options	-0.3	0.5
Valuation allowance, operating loss carryforwards	7.5
Valuation allowance, capital loss	1.1
Expiration of foreign tax credits	2024
Valuation allowance on foreign tax credits	15.2
Unrecognized tax benefits	6	4.5
Interest expense and related penalties	1.5	-0.1	0.3
Accrued interest expense and penalties	2.7	1.2
State [Member]
Income Taxes [Line Items]
Net operating losses	9.5
State [Member] \| Maximum [Member]
Income Taxes [Line Items]
Expiration of operating loss carryforwards	2034
State [Member] \| Minimum [Member]
Income Taxes [Line Items]
Expiration of operating loss carryforwards	2015
Foreign [Member]
Income Taxes [Line Items]
Net operating losses	8.6
Expiration of operating loss carryforwards	2018
Foreign [Member] \| Expiry in 2018 [Member]
Income Taxes [Line Items]
Net operating losses	5.1
Foreign Subsidiary [Member]
Income Taxes [Line Items]
Undistributed earnings	$127

Income_Taxes_Summary_of_Income1

Income Taxes - Summary of Income Taxes Reconciled with Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Federal income tax rate	35.00%	35.00%	35.00%
State income taxes, net of federal tax benefit	-4.80%	2.10%	-0.50%
Foreign earnings taxed at different rates	-440.00%	15.50%	0.50%
Domestic production activities deduction	40.80%	-2.00%	-2.70%
Deferred tax adjustments	3.20%	-0.20%	-0.30%
Change in tax contingency reserves	-15.20%	-1.50%	1.20%
Legal entity tax restructuring project	-1503.20%	0.00%	0.00%
Foreign tax credits	1203.40%	-1.10%	-0.60%
Changes to foreign repatriation plans	104.00%	0.00%	0.00%
Other	-1.20%	0.00%	0.50%
Total effective tax rate	-578.00%	47.80%	33.10%

Income_Taxes_Summary_of_Deferr

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Pension and other postretirement benefits obligations	$19.20	$10.30
Tax credits	16.1	10.3
Net operating loss benefit	14.6	10
Reserves, including insurance, environmental and deferred revenue	12.4	16.5
Asset retirement obligations	7.5	6.8
Accrued employee compensation	6.7	9.4
Book/tax inventory accounting differences	3.6	3.3
Book over tax depreciation and amortization	3.2	1.3
Capital loss benefit	1.1	1.1
Other	6.4	2.2
Valuation allowance	-32.4	-19.7
Total deferred tax assets	58.4	51.5
Deferred tax liabilities:
Tax over book depreciation and amortization	49	35.4
Unremitted earnings of foreign subsidiaries	0.5	6.8
Tax/book inventory accounting differences	0.2	1.1
Other	0.6	3.7
Total deferred tax liabilities	50.3	47
Net deferred tax assets	$8.10	$4.50

Income_taxes_Summary_of_Unreco

Income taxes - Summary of Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Balance at beginning of year	$6.10	$7.70	$9.90
Additions based on tax provisions related to the current year	0.6	0.4	0.5
Additions for tax provisions of prior years	1.9	0.4	1.3
Additions as a result of acquisitions	1.6	0	0
Reductions of tax provisions of prior years	-0.7	-0.8	-0.5
Reductions as a result of payments and settlements	0	-1.1	-2.8
Reductions as a result of a lapse of the applicable statute of limitations	-0.6	-0.5	-0.7
Balance at end of year	$8.90	$6.10	$7.70

Inventories_Components_of_Inve

Inventories - Components of Inventories (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials	$191.10	$105.40
Work in process	2.6	19.2
Finished goods	103.6	94.8
Inventories, gross	297.3	219.4
Less revaluation to LIFO	56.1	50.6
Net	$241.20	$168.80

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013
Inventory Disclosure [Abstract]
Increase in operating profit due to LIFO liquidations	$0.20

Equity_Investments_Additional_

Equity Investments - Additional Information (Detail) (USD $)	36 Months Ended
	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Ownership percentage	30.00%
Dividends received from equity method investment	$0
KSA Limited Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Tangshan Koppers Kailuan Carbon Chemical Company Limited [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	30.00%

Equity_Investments_Equity_Earn

Equity Investments - Equity Earnings (Losses) and Dividends Received (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity Method Investments and Joint Ventures [Abstract]
Equity (loss) income	($1.60)	$0.80	$0.80

Property_Plant_and_Equipment_P

Property, Plant and Equipment - Property, Plant and Equipment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$742.60	$647.80
Less accumulated depreciation	442.9	450.8
Net	299.7	197
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	18.7	9.1
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	45.3	30.6
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$678.60	$608.10

Property_Plant_and_Equipment_A

Property, Plant and Equipment - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Oct. 31, 2013	Feb. 29, 2012	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Battery	T	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Depreciation, including impairment charges				$38.80	$38.30	$25.20
Impairment charges			6.9	4.7	11.9	0.6
Impairment charges, discontinued operations						0.6
Number of coke batteries to be closed	2
Number of coke batteries closed	2
Supply of export commitments				30.00%
Liquid carbon pitch leaked from storage tank		400
Cost associated with leak						2.5
Estimated insurance recoveries, net			1.2	0.1	1.2
Koppers Carbon and Chemical Company Limited [Member]
Property, Plant and Equipment [Line Items]
Percentage of operations in Tangshan, China of owned subsidiary				60.00%
Carbon Materials and Chemicals [Member]
Property, Plant and Equipment [Line Items]
Impairment charges				4.7	11.9
China [Member]
Property, Plant and Equipment [Line Items]
Percentage of operations in Tangshan, China of owned subsidiary				60.00%
China [Member] \| Carbon Materials and Chemicals [Member]
Property, Plant and Equipment [Line Items]
Asset impairment charges, net of non-controlling interest				$2.80

Goodwill_and_Other_Identifiabl2

Goodwill and Other Identifiable Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Balance beginning	$72.70	$75.60
Acquisitions	180.6
Currency translation	-6.1	-2.9
Balance ending	247.2	72.7
Carbon Materials and Chemicals [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Balance beginning	68	70.2
Acquisitions	0
Currency translation	-2.5	-2.2
Balance ending	65.5	68
Railroad and Utility Products and Services [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Balance beginning	4.7	5.4
Acquisitions	5.2
Currency translation	-0.6	-0.7
Balance ending	9.3	4.7
Performance Chemicals [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Balance beginning	0	0
Acquisitions	175.4
Currency translation	-3	0
Balance ending	$172.40	$0

Goodwill_and_Other_Identifiabl3

Goodwill and Other Identifiable Intangible Assets - Schedule of Identifiable Intangible Assets (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average remaining life in years	13 years 2 months 12 days
Gross Carrying Amount	$187.10	$25.10
Accumulated Amortization	19.4	12.9
Net	167.7	12.2
Customer Contracts [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average remaining life in years	14 years 9 months 18 days
Gross Carrying Amount	149.9	19.8
Accumulated Amortization	14.5	9.7
Net	135.4	10.1
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average remaining life in years	7 years
Gross Carrying Amount	26.7	0
Accumulated Amortization	1.4	0
Net	25.3	0
Trademarks [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average remaining life in years	6 years 6 months
Gross Carrying Amount	5.6	0
Accumulated Amortization	0.3	0
Net	5.3	0
Supply Contracts [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	10 years
Weighted average remaining life in years	5 years 2 months 12 days
Gross Carrying Amount	2.6	2.9
Accumulated Amortization	1.2	1.1
Net	1.4	1.8
Non-Compete Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	12 years
Weighted average remaining life in years	9 years 9 months 18 days
Gross Carrying Amount	1.5	1.6
Accumulated Amortization	1.2	1.3
Net	0.3	0.3
Favorable Lease Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	3 years
Weighted average remaining life in years	0 years
Gross Carrying Amount	0.8	0.8
Accumulated Amortization	0.8	0.8
Net	$0	$0
Minimum [Member] \| Customer Contracts [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	9 years
Minimum [Member] \| Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	4 years
Minimum [Member] \| Trademarks [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	4 years
Maximum [Member] \| Customer Contracts [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	17 years
Maximum [Member] \| Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	12 years
Maximum [Member] \| Trademarks [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated life in years	7 years

Goodwill_and_Other_Identifiabl4

Goodwill and Other Identifiable Intangible Assets - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill And Other Intangible Assets [Line Items]
Amortization expense	$8.40	$2.10	$1.90
Customer Relationships [Member]
Goodwill And Other Intangible Assets [Line Items]
Acquired intangible assets	133.8
Technology [Member]
Goodwill And Other Intangible Assets [Line Items]
Acquired intangible assets	26.9
Trademarks [Member]
Goodwill And Other Intangible Assets [Line Items]
Acquired intangible assets	5.6
Foreign Currency Translation [Member]
Goodwill And Other Intangible Assets [Line Items]
Decrease in carrying value of identifiable intangible assets	$2.20

Goodwill_and_Other_Identifiabl5

Goodwill and Other Identifiable Intangible Assets - Schedule of Future Amortization Expense (Detail) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
2015	$14.90
2016	14.5
2017	14.3
2018	14.3
2019	$14.20

Pensions_and_Postretirement_Be2

Pensions and Postretirement Benefit Plans - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Plans	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Number of domestic non-qualified defined benefit plans	3
Defined contribution plan expense	$6.90	$5.30	$4.70
Multi-employer contribution plan expense	0.2	0.4	0.4
Amortization of prior service cost in 2015	-0.3
Amortization of net loss in 2015	6.3
Accumulated benefit obligation, pension plans	269	230.6
Operating expenses	3.8	2.3	5.2
Growth seeking assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation investment strategy, minimum	30.00%
Target allocation investment strategy, maximum	40.00%
Income generating assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation investment strategy, minimum	60.00%
Target allocation investment strategy, maximum	70.00%
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	7.15%
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	4.50%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions by employer	3.1
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions by employer	$0.70
Initial health care cost trend rate	6.95%	7.15%

Pensions_and_Postretirement_Be3

Pensions and Post-retirement Benefit Plans - Components of Net Periodic Benefit Cost for Pension Plans and Other Benefit Plans (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$2.70	$3.40	$3.50
Interest cost	11.8	10.7	10.7
Expected return on plan assets	-13.9	-12.5	-10.7
Amortization of prior service cost	-0.2	0.1	0.1
Amortization of net loss	4	7.6	8.1
Amortization of transition asset	0	0	-0.3
Settlements and curtailments	0	0.1	0.3
Net periodic benefit cost	4.4	9.4	11.7
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.1	0.1	0.1
Interest cost	0.5	0.5	0.5
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Amortization of net loss	0.2	-0.1	0
Amortization of transition asset	0	0	0
Settlements and curtailments	0	0	0
Net periodic benefit cost	$0.40	$0.50	$0.60

Pensions_and_Postretirement_Be4

Pensions and Post-retirement Benefit Plans - Schedule of Change in Funded Status of Pension and Post-Retirement Plans (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	$229.50	$205.70
Noncurrent liabilities	54.7	41.6
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	237.8	255.2
Service cost	2.7	3.4	3.5
Interest cost	11.8	10.7	10.7
Plan participants' contributions	0.2	0.2
Actuarial losses (gains)	39.4	-18.6
Plan amendments	0	-1.5
Settlements	0	-0.9
Currency translation	-4.4	0.2
Benefits paid	-11.8	-10.9
Benefit obligation at end of year	275.7	237.8	255.2
Fair value of plan assets at beginning of year	205.7	175.6
Actual return on plan assets	24	19.2
Employer contribution	15.1	22.5
Plan participants' contributions	0.2	0.2
Settlements	0	-0.9
Currency translation	-3.7	0
Benefits paid	-11.8	-10.9
Fair value of plan assets at end of year	229.5	205.7	175.6
Funded status of the plan	-46.2	-32.1
Noncurrent assets	0.2	0.6
Current liabilities	0.9	0.7
Noncurrent liabilities	45.5	32
Benefit obligation	237	231.9
Fair value of plan assets	200.2	199.2
Accumulated benefit obligation	230.7	225
Fair value of plan assets	200.2	199.2
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	10.4	11.2
Service cost	0.1	0.1	0.1
Interest cost	0.5	0.5	0.5
Plan participants' contributions	0	0
Actuarial losses (gains)	-1.1	-1.3
Plan amendments	0	0
Settlements	0	0
Currency translation	0	0
Benefits paid	-0.1	-0.1
Benefit obligation at end of year	9.8	10.4	11.2
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contribution	0.1	0.1
Plan participants' contributions	0	0
Settlements	0	0
Currency translation	0	0
Benefits paid	-0.1	-0.1
Fair value of plan assets at end of year	0	0	0
Funded status of the plan	-9.8	-10.4
Noncurrent assets	0	0
Current liabilities	0.7	0.8
Noncurrent liabilities	$9.10	$9.60

Pensions_and_Postretirement_Be5

Pensions and Post-retirement Benefit Plans - Schedule of Projected Benefit Payments (Detail) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified	Dec. 31, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2015	$12.10
2016	12.4
2017	13.3
2018	14.3
2019	13.8
2020 - 2024	78.9
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2015	0.7
2016	0.7
2017	0.7
2018	0.7
2019	0.8
2020 - 2024	$3.10

Pensions_and_Postretirement_Be6

Pensions and Post-retirement Benefit Plans - Schedule of Weighted-Average Assumptions (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.12%	5.06%
Expected return on plan assets	6.31%	7.04%
Rate of compensation increase	4.00%	3.13%
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.32%	5.25%
Initial medical trend rate	6.95%	7.15%

Pensions_and_Postretirement_Be7

Pensions and Post-retirement Benefit Plans - Schedule of Weighted Average Asset Allocation for Company's Pension Plans (Detail)	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Total asset allocation	100.00%	100.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total asset allocation	71.00%	59.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total asset allocation	26.00%	38.00%
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total asset allocation	3.00%	3.00%

Pensions_and_Postretirement_Be8

Pensions and Post-retirement Benefit Plans - Schedule of Pension Plan Assets at Fair Value (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$229.50	$205.70
U.S. equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	28	33.7
International equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	32.7	44.3
U.S. debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	128.5	89.5
International debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	34.6	32.3
Real estate and other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.9	1.5
Cash & Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3.8	4.4
Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	74.4	50
Quoted prices in active markets for identical assets (Level 1) [Member] \| U.S. equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	17.5	17.8
Quoted prices in active markets for identical assets (Level 1) [Member] \| International equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	12.7	0
Quoted prices in active markets for identical assets (Level 1) [Member] \| U.S. debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	36.4	24.8
Quoted prices in active markets for identical assets (Level 1) [Member] \| International debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	7.8	7.4
Quoted prices in active markets for identical assets (Level 1) [Member] \| Real estate and other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Quoted prices in active markets for identical assets (Level 1) [Member] \| Cash & Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Significant observable inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	155.1	155.7
Significant observable inputs (Level 2) [Member] \| U.S. equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	10.5	15.9
Significant observable inputs (Level 2) [Member] \| International equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	20	44.3
Significant observable inputs (Level 2) [Member] \| U.S. debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	92.1	64.7
Significant observable inputs (Level 2) [Member] \| International debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	26.8	24.9
Significant observable inputs (Level 2) [Member] \| Real estate and other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.9	1.5
Significant observable inputs (Level 2) [Member] \| Cash & Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3.8	4.4
Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Significant unobservable inputs (Level 3) [Member] \| U.S. equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Significant unobservable inputs (Level 3) [Member] \| International equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Significant unobservable inputs (Level 3) [Member] \| U.S. debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Significant unobservable inputs (Level 3) [Member] \| International debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Significant unobservable inputs (Level 3) [Member] \| Real estate and other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0	0
Significant unobservable inputs (Level 3) [Member] \| Cash & Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$0	$0

Pensions_and_Postretirement_Be9

Pensions and Post-retirement Benefit Plans - Schedule of Health Care Cost Trend Rates (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Postemployment Benefits [Abstract]
Postretirement benefit expense one-percentage increase	$0
Postretirement benefit liability one-percentage increase	0.2
Postretirement benefit expense one-percentage decrease	0
Postretirement benefit liability one-percentage decrease	($0.20)

Debt_Schedule_of_LongTerm_Debt

Debt - Schedule of Long-Term Debt Instruments (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Total debt	$850.50	$303.10
Less short term debt and current maturities of long-term debt	43.9	0
Long-term debt	806.6	303.1
Total debt	850.5	303.1
Term Loan [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	3.63%
Debt, Maturity	2019
Total debt	292.5	0
Total debt	292.5	0
Construction Loans [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.81%
Debt, Maturity	2018
Total debt	56.5	6.6
Total debt	56.5	6.6
Senior Notes [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	7.88%
Debt, Maturity	2019
Total debt	297	296.5
Long-term debt	806.6	303.1
Total debt	297	296.5
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	3.63%
Debt, Maturity	2019
Total debt	204.5	0
Total debt	$204.50	$0

Debt_Additional_Information_De

Debt - Additional Information (Detail)

Dec. 31, 2014

Dec. 31, 2013

Aug. 15, 2014

Dec. 31, 2014

Aug. 15, 2014

Dec. 31, 2014

Dec. 01, 2009

Dec. 31, 2014

Dec. 01, 2009

Nov. 18, 2013

Dec. 31, 2014

Nov. 18, 2013

USD ($)

Revolving Credit Facility [Member]

Koppers Carbon and Chemical Company Limited [Member]

Senior Notes [Member]

Construction Loans [Member]

USD ($)

Installment

Third Party Debt [Member]

Lender [Member]

Koppers Carbon and Chemical Company Limited [Member]

CNY

Committed Credit Facility [Member]

USD ($)

CNY

Debt Instrument [Line Items]

Revolving credit facility

$350,000,000

Revolving credit facility, current borrowing capacity

500,000,000

Senior secured term loan for acquiring Osmose

300,000,000

Revolving credit facility, borrowing maturity date

19-Aug-13

Initial interest rate

3.25%

Quarterly principal repayment obligations, interest rate

2.50%

Quarterly principal repayment obligations

7,500,000

Debt instrument, unused borrowing capacity

113,500,000

Letters of credit, amount outstanding

61,500,000

Percentage of owned subsidiary

60.00%

100.00%

75.00%

Construction loan facility borrowing capacity

198,800,000

66,200,000

44,000,000

265,000,000

Percentage of non-controlling shareholders

25.00%

Debt maturity date

18-Nov-18

Number of installments for repayment of loans

Installment frequency for repayment of loans

6 months

Commencement period of debt repayment

2016-05

Debt, Weighted Average Interest Rate

3.63%

7.88%

5.81%

Debt instrument, issuance date

1-Dec-09

Debt instrument, offering price percentage

98.31%

Debt instrument, offering value

294,900,000

Debt instrument, face amount

300,000,000

Debt instrument, effective interest rate

8.13%

Debt instrument, redemption price percentage

103.94%

Frequency of interest payment on senior notes

Interest on the Senior Notes is payable semiannually on December 1 and June 1 each year

Accumulated amortization

3,900,000

5,900,000

Unamortized deferred financing costs

$14,500,000

$7,200,000

Debt_Schedule_of_Debt_Maturiti

Debt - Schedule of Debt Maturities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
2015	$43.90
2016	36.4
2017	44.9
2018	51.3
2019	677
Thereafter	0
Total maturities	853.5
Future accretion on Senior Notes	-3
Total debt	$850.50	$303.10

Leases_Future_Minimum_Commitme

Leases - Future Minimum Commitments for Operating Leases (Detail) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified	Dec. 31, 2014
Leases [Abstract]
2015	$35.60
2016	30.5
2017	27.5
2018	21.2
2019	7.6
Thereafter	33.7
Total	$156.10

Leases_Additional_Information_

Leases - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Leases [Abstract]
Operating lease expense	$36.70	$39.40	$44.30

Derivative_Financial_Instrumen1

Derivative Financial Instruments - Additional Information (Detail)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014
		Copper Swap Contracts [Member]	Copper Swap Contracts [Member]	Accrued Liabilities [Member]	Accrued Liabilities [Member]	Forward Contracts [Member]	Forward Contracts [Member]	Forward Contracts [Member]
		USD ($)	Commodity Price [Member]	Copper Swap Contracts [Member]	Copper Swap Contracts [Member]	USD ($)	CAD	GBP (£)
			USD ($)	USD ($)	GBP (£)
Derivative [Line Items]
Maximum period hedged in cash flow hedge	30 months
Derivative fair value, net				($6.50)	£ 19.6	$0
Change in derivative financial instrument, net loss		3.8
Ineffective portion of swap contracts charged to cost of sales		0.1
Unrealized losses, net of tax			2.8
Gross derivative assets						0.2
Gross derivative liability						0.2
Currency units outstanding						$7.60	8	£ 15.6

Common_Stock_and_Senior_Conver2

Common Stock and Senior Convertible Preferred Stock - Schedule of Changes in Senior Convertible Preferred Stock, Common Stock and Treasury Stock (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Senior Convertible Preferred Stock:
Balance at beginning and end of year	0	0	0
Common Stock:
Balance at beginning of year	21,722,492	21,585	21,309
Issued for employee stock plans	216,000	137,000	276,000
Balance at end of year	21,938,260	21,722,492	21,585
Treasury Stock:
Balance at beginning of year	-1,390,494	-951	-706
Shares repurchased	-53,000	-439,000	-245,000
Balance at end of year	-1,443,248	-1,390,494	-951

Commitments_and_Contingent_Lia2

Commitments and Contingent Liabilities - Additional Information (Detail)

1 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

Jul. 31, 2013

Sep. 30, 2012

Jul. 31, 2012

Jul. 31, 2004

Dec. 31, 2014

Dec. 31, 2013

Mar. 30, 2012

Jan. 19, 2015

Dec. 31, 2014

Dec. 31, 2011

USD ($)

Subsequent Event [Member]

Compensatory Damages [Member]

Punitive Damages [Member]

Pennsylvania [Member]

Arkansas [Member]

Tennessee [Member]

Australia [Member]

State

Plaintiff

site

EUR (€)

Cases

USD ($)

site

Cases

Plaintiff

Cases

Commitments And Contingent Liabilities [Line Items]

Number of states with new claims filed

Number of plaintiffs

112

111

Number of cases

Compensatory damages

$3,100,000

$1,700,000

$15,000,000

Plant operation resumption period

21 days

Legal settlement

1,400,000

Environmental legal indemnification expense

7,000,000

Sites listed on National Priorities List

Environmental remediation costs paid by others, per year

13,000,000

Environmental Protection Agency

Possible remedial alternatives

Remedial alternatives

170,000,000

Remedial alternatives

1,800,000,000

Environmental contingencies reserve not provided by company

700,000

Environmental remediation expense

4,100,000

1,600,000

Amount contributable by third party

7,500,000

Environmental remediation reserve

800,000

1,800,000

900,000

Net amount contributed by third party

800,000

Accrued liability for environmental matters, current

$3,300,000

$8,200,000

Commitments_and_Contingent_Lia3

Commitments and Contingent Liabilities - Changes in Accrued Liability for Environmental Matters (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of year	$11.90	$14.10
Expense	0.8	1.8
Reversal of reserves	-1.5	-1.2
Cash expenditures	-3.7	-0.9
Acquisition	0.7	0
Currency translation	-0.4	-1.9
Balance at end of year	$7.80	$11.90

Related_Party_Transactions_Add

Related Party Transactions - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Loan to related party	$9.50	$9.50
Ownership percentage	30.00%
Equity Method Investee [Member]
Related Party Transaction [Line Items]
Loan to related party	$9.50
Ownership percentage	30.00%
Loan repayable date	2015-11
Loan repayable beginning date	2015-06

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data - Schedule of Selected Quarterly Financial Data (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of operations data:
Net sales	$426.70	$440.10	$356.80	$331.40	$341.80	$395.20	$370.90	$370.40	$1,555	$1,478.30	$1,555
Operating profit	2.1	17.3	13.3	0.5	7.8	39.1	28.5	24.9	33.2	100.3	126.6
Income (loss) from continuing operations	-36.4	-4.3	0.8	-0.1	-5.6	19.6	14.8	11.4	-40	40.2	67.3
Net income	-35.8	-4.2	0.7	-0.1	-5.6	19.5	14.7	11.5	-39.4	40.1	67.2
Net income (loss) attributable to Koppers	($33.50)	($2.70)	$1.60	$2.20	($4.10)	$19.10	$14.40	$11	($32.40)	$40.40	$65.60
Basic -
Continuing operations	($1.66)	($0.14)	$0.08	$0.11	($0.20)	$0.93	$0.70	$0.53	($1.61)	$1.96	$3.18
Discontinued operations	$0.03	$0	$0	$0	$0	$0	($0.01)	$0	$0.03	$0	($0.01)
Earnings (loss) per basic common share	($1.63)	($0.14)	$0.08	$0.11	($0.20)	$0.93	$0.69	$0.53	($1.58)	$1.96	$3.17
Diluted -
Continuing operations	($1.66)	($0.14)	$0.08	$0.11	($0.20)	$0.92	$0.70	$0.53	($1.61)	$1.94	$3.14
Discontinued operations	$0.03	$0	$0	$0	$0	$0	($0.01)	$0	$0.03	$0	($0.01)
Earnings (loss) per diluted common share	($1.63)	($0.14)	$0.08	$0.11	($0.20)	$0.92	$0.69	$0.53	($1.58)	$1.94	$3.13
Dividends declared per common share	$0.25	$0.25	$0.25	$0.25	$0.25	$0.25	$0.25	$0.25	$1	$1	$0.96
Maximum [Member]
Price range of common stock:
Price range of common stock	$39.88	$39.45	$45.51	$45.92	$49.99	$42.43	$46.48	$45.72	$45.92	$49.99
Minimum [Member]
Price range of common stock:
Price range of common stock	$22.52	$33.02	$35.53	$35.51	$41.61	$34.69	$37.45	$38.70	$22.52	$34.69

Selected_Quarterly_Financial_D3

Selected Quarterly Financial Data - Schedule of Selected Quarterly Financial Data (Parenthetical) (Detail) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Fixed asset impairment charges		$6.90	$4.70	$11.90	$0.60
Income taxes	$24.30

Subsidiary_Guarantor_Informati2

Subsidiary Guarantor Information for Koppers Inc. Senior Notes - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Dec. 01, 2009	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Aug. 15, 2014
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit facility, current borrowing capacity					$500,000,000
Revolving credit facility					350,000,000
Senior Notes [Member]
Debt Instrument [Line Items]
Principal value of Senior Notes	300,000,000
Percent-owned material domestic subsidiaries	100.00%
Payment Guarantee by Subsidiaries for Senior Notes [Member]
Debt Instrument [Line Items]
Revolving credit facility, current borrowing capacity		500,000,000
Cash dividends paid		23,600,000	38,500,000	27,600,000
Payment Guarantee by Subsidiaries for Senior Notes [Member] \| Term Loan Facility [Member]
Debt Instrument [Line Items]
Revolving credit facility		300,000,000
Payment Guarantee by Subsidiaries for Senior Notes [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Restricted net assets		$20,000,000

Subsidiary_Guarantor_Informati3

Subsidiary Guarantor Information for Koppers Inc. Senior Notes - Condensed Consolidating Statement of Comprehensive Income (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Subsidiary Guarantor Information For Subsidiary Senior Notes [Line Items]
Net sales	$426.70	$440.10	$356.80	$331.40	$341.80	$395.20	$370.90	$370.40	$1,555	$1,478.30	$1,555
Selling, general and administrative									116.2	71.7	75.6
Operating profit (loss)	2.1	17.3	13.3	0.5	7.8	39.1	28.5	24.9	33.2	100.3	126.6
Other income (expense)									0	3.5	1.9
Equity income of subsidiaries									-1.6	0.8	0.8
Interest expense									39.1	26.8	27.9
Income taxes									34.1	36.8	33.3
(Loss) income from continuing operations	-36.4	-4.3	0.8	-0.1	-5.6	19.6	14.8	11.4	-40	40.2	67.3
Discontinued operations									0.6	-0.1	-0.1
Noncontrolling interests									-7	-0.3	1.6
Net (loss) income attributable to Koppers	-33.5	-2.7	1.6	2.2	-4.1	19.1	14.4	11	-32.4	40.4	65.6
Comprehensive (loss) income attributable to Koppers									-82.5	52.3	73.7
Intersegment [Member]
Subsidiary Guarantor Information For Subsidiary Senior Notes [Line Items]
Net sales									87.8	94.2	106.5
Senior Notes [Member]
Subsidiary Guarantor Information For Subsidiary Senior Notes [Line Items]
Net sales									1,555	1,478.30	1,555
Cost of sales including depreciation and amortization									1,405.60	1,306.30	1,352.80
Selling, general and administrative									116.2	71.7	75.6
Operating profit (loss)									33.2	100.3	126.6
Other income (expense)									0	3.5	1.9
Equity income of subsidiaries									0	0	0
Interest expense									39.1	26.8	27.9
Income taxes									34.1	36.8	33.3
(Loss) income from continuing operations									-40	40.2	67.3
Discontinued operations									0.6	-0.1	-0.1
Noncontrolling interests									-7	-0.3	1.6
Net (loss) income attributable to Koppers									-32.4	40.4	65.6
Comprehensive (loss) income attributable to Koppers									-82.5	52.3	73.7
Senior Notes [Member] \| Intersegment [Member]
Subsidiary Guarantor Information For Subsidiary Senior Notes [Line Items]
Net sales									-67.4	-49.4	-74.1
Cost of sales including depreciation and amortization									-66.7	-49.5	-73.8
Selling, general and administrative									0	0	0
Operating profit (loss)									-0.7	0.1	-0.3
Other income (expense)									-4.3	-4.1	-5.2
Equity income of subsidiaries									53.3	-70.6	-136.3
Interest expense									-4.3	-4.1	-5.3
Income taxes									0	0	0
(Loss) income from continuing operations									52.6	-70.5	-136.5
Discontinued operations									0	0	0
Noncontrolling interests									0	0	0
Net (loss) income attributable to Koppers									52.6	-70.5	-136.5
Comprehensive (loss) income attributable to Koppers									170.6	-75.7	-151.2
Senior Notes [Member] \| Parent [Member]
Subsidiary Guarantor Information For Subsidiary Senior Notes [Line Items]
Net sales									0	0	0
Cost of sales including depreciation and amortization									0	0	0
Selling, general and administrative									2.2	1.9	1.6
Operating profit (loss)									-2.2	-1.9	-1.6
Other income (expense)									0	0	0
Equity income of subsidiaries									-31	41.7	66.6
Interest expense									0	0	0
Income taxes									-0.8	-0.6	-0.6
(Loss) income from continuing operations									-32.4	40.4	65.6
Discontinued operations									0	0	0
Noncontrolling interests									0	0	0
Net (loss) income attributable to Koppers									-32.4	40.4	65.6
Comprehensive (loss) income attributable to Koppers									-82.5	52.3	73.7
Senior Notes [Member] \| Koppers Inc. [Member]
Subsidiary Guarantor Information For Subsidiary Senior Notes [Line Items]
Net sales									795.9	843.7	893.2
Cost of sales including depreciation and amortization									724.5	745.4	786.6
Selling, general and administrative									59.2	41.5	45.1
Operating profit (loss)									12.2	56.8	61.5
Other income (expense)									0.2	1.3	0.4
Equity income of subsidiaries									-15.9	17.5	40.8
Interest expense									36.5	26.7	27.4
Income taxes									-9	7.3	8.7
(Loss) income from continuing operations									-31	41.6	66.6
Discontinued operations									0	0.1	0
Noncontrolling interests									0	0	0
Net (loss) income attributable to Koppers									-31	41.7	66.6
Comprehensive (loss) income attributable to Koppers									-81.1	53.5	74.8
Senior Notes [Member] \| Domestic Guarantor Subsidiaries [Member]
Subsidiary Guarantor Information For Subsidiary Senior Notes [Line Items]
Net sales									143	61.8	97.5
Cost of sales including depreciation and amortization									108.8	43.5	78
Selling, general and administrative									17.4	0.7	2.1
Operating profit (loss)									16.8	17.6	17.4
Other income (expense)									4.7	4.2	6.1
Equity income of subsidiaries									-6.4	11.4	28.8
Interest expense									0	0	0
Income taxes									30.5	16.4	12.5
(Loss) income from continuing operations									-15.4	16.8	39.8
Discontinued operations									-0.6	0	0
Noncontrolling interests									0	0	0
Net (loss) income attributable to Koppers									-16	16.8	39.8
Comprehensive (loss) income attributable to Koppers									-54.4	8.4	44
Senior Notes [Member] \| Non-Guarantor Subsidiaries [Member]
Subsidiary Guarantor Information For Subsidiary Senior Notes [Line Items]
Net sales									683.5	622.2	638.4
Cost of sales including depreciation and amortization									639	566.9	562
Selling, general and administrative									37.4	27.6	26.8
Operating profit (loss)									7.1	27.7	49.6
Other income (expense)									-0.6	2.1	0.6
Equity income of subsidiaries									0	0	0.1
Interest expense									6.9	4.2	5.8
Income taxes									13.4	13.7	12.7
(Loss) income from continuing operations									-13.8	11.9	31.8
Discontinued operations									1.2	-0.2	-0.1
Noncontrolling interests									-7	-0.3	1.6
Net (loss) income attributable to Koppers									-5.6	12	30.1
Comprehensive (loss) income attributable to Koppers									($35.10)	$13.80	$32.40

Subsidiary_Guarantor_Informati4

Subsidiary Guarantor Information for Koppers Inc. Senior Notes - Condensed Consolidating Balance Sheet (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$51.10	$82.20	$66.70	$54.10
Receivables, net	198.7	157.9
Inventories, net	241.2	168.8
Deferred tax assets	10.5	10
Other current assets	30.3	35.7
Total current assets	541.3	473.1
Equity investments	5	6.6
Property, plant and equipment, net	299.7	197
Goodwill	247.2	72.7	75.6
Intangible assets, net	167.7	12.2
Deferred tax assets	7.8	9.3
Other noncurrent assets	25.2	14
Total assets	1,293.90	784.9
LIABILITIES AND EQUITY
Accounts payable	120.6	107.6
Accrued liabilities	122.5	82.4
Short-term debt and current portion of long-term debt	43.9	0
Total current liabilities	292.1	195.1
Long-term debt	806.6	303.1
Other long-term liabilities	46.4	40.6
Total liabilities	1,210	595.1
Koppers shareholders' equity	70	169.8
Noncontrolling interests	13.9	20
Total liabilities and equity	1,293.90	784.9
Senior Notes [Member]
Assets
Cash and cash equivalents	51.1	82.2	66.7	54.1
Receivables, net	198.7	166.9
Affiliated receivables	0	0
Inventories, net	241.2	168.8
Deferred tax assets	10.5	10
Other current assets	39.8	45.2
Total current assets	541.3	473.1
Equity investments	5	6.6
Property, plant and equipment, net	299.7	197
Goodwill	247.2	72.7
Intangible assets, net	167.7
Deferred tax assets		9.3
Deferred tax assets	7.8
Affiliated loan receivables	0	0
Other noncurrent assets	25.2	26.2
Total assets	1,293.90	784.9
LIABILITIES AND EQUITY
Accounts payable	120.6	107.6
Affiliated payables	0	0
Accrued liabilities	127.6	87.5
Short-term debt and current portion of long-term debt	43.9
Total current liabilities	292.1	195.1
Long-term debt	806.6	303.1
Affiliated debt	0	0
Other long-term liabilities	111.3
Other long-term liabilities		96.9
Total liabilities	1,210	595.1
Koppers shareholders' equity	70	169.8
Noncontrolling interests	13.9	20
Total liabilities and equity	1,293.90	784.9
Senior Notes [Member] \| Intersegment [Member]
Assets
Cash and cash equivalents	0	0	0	0
Receivables, net	0	0
Affiliated receivables	-15.9	-7.5
Inventories, net	-1	-0.2
Deferred tax assets	0	0
Other current assets	0	0
Total current assets	-16.9	-7.7
Equity investments	-1,053.80	-689.1
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0
Deferred tax assets		0
Deferred tax assets	0
Affiliated loan receivables	-293.4	-173.2
Other noncurrent assets	0	0
Total assets	-1,364.10	-870
LIABILITIES AND EQUITY
Accounts payable	0	0
Affiliated payables	-29.4	-14.5
Accrued liabilities	0	0
Short-term debt and current portion of long-term debt	0
Total current liabilities	-29.4	-14.5
Long-term debt	0	0
Affiliated debt	293.4	-173.2
Other long-term liabilities	0
Other long-term liabilities		0
Total liabilities	-322.8	-187.7
Koppers shareholders' equity	-1,041.30	-682.3
Noncontrolling interests	0	0
Total liabilities and equity	-1,364.10	-870
Senior Notes [Member] \| Parent [Member]
Assets
Cash and cash equivalents	0	0	0	0
Receivables, net	0	0
Affiliated receivables	0.8	0.2
Inventories, net	0	0
Deferred tax assets	0	0
Other current assets	0	0
Total current assets	0.8	0.2
Equity investments	74.5	174.7
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0
Deferred tax assets		0
Deferred tax assets	0
Affiliated loan receivables	0	0
Other noncurrent assets	0	0
Total assets	75.3	174.9
LIABILITIES AND EQUITY
Accounts payable	0.1	0
Affiliated payables	0	0
Accrued liabilities	5.2	5.1
Short-term debt and current portion of long-term debt	0
Total current liabilities	5.3	5.1
Long-term debt	0	0
Affiliated debt	0	0
Other long-term liabilities	0
Other long-term liabilities		0
Total liabilities	5.3	5.1
Koppers shareholders' equity	70	169.8
Noncontrolling interests	0	0
Total liabilities and equity	75.3	174.9
Senior Notes [Member] \| Koppers Inc. [Member]
Assets
Cash and cash equivalents	0	29.9	4.8	0
Receivables, net	75.7	75.6
Affiliated receivables	4.5	1.1
Inventories, net	108.8	86.1
Deferred tax assets	8	7.9
Other current assets	3	7.3
Total current assets	200	207.9
Equity investments	767.2	333.5
Property, plant and equipment, net	121.2	112.2
Goodwill	39.8	39.8
Intangible assets, net	2.2
Deferred tax assets		2.4
Deferred tax assets	-1
Affiliated loan receivables	40.5	8.5
Other noncurrent assets	19.1	15
Total assets	1,189	719.3
LIABILITIES AND EQUITY
Accounts payable	60.9	48.3
Affiliated payables	13.2	1.9
Accrued liabilities	37.9	27.8
Short-term debt and current portion of long-term debt	30
Total current liabilities	142	78
Long-term debt	764	296.5
Affiliated debt	145.5	109.5
Other long-term liabilities	68.6
Other long-term liabilities		67.6
Total liabilities	1,120.10	551.6
Koppers shareholders' equity	68.9	167.7
Noncontrolling interests	0	0
Total liabilities and equity	1,189	719.3
Senior Notes [Member] \| Domestic Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	0.9	0.1	0	0
Receivables, net	20	9.3
Affiliated receivables	9.3	3.9
Inventories, net	30.8	0
Deferred tax assets	1	1.5
Other current assets	2.2	0.6
Total current assets	64.2	15.4
Equity investments	213.5	182.9
Property, plant and equipment, net	43.1	0
Goodwill	149.9	0
Intangible assets, net	128.1
Deferred tax assets		-1.4
Deferred tax assets	1.1
Affiliated loan receivables	212	123.8
Other noncurrent assets	5.2	0
Total assets	817.1	320.7
LIABILITIES AND EQUITY
Accounts payable	9	6.7
Affiliated payables	2.7	4
Accrued liabilities	29.5	0.5
Short-term debt and current portion of long-term debt	0
Total current liabilities	41.2	11.2
Long-term debt	0	0
Affiliated debt	35.9	8.5
Other long-term liabilities	7.7
Other long-term liabilities		2.5
Total liabilities	84.8	22.2
Koppers shareholders' equity	732.3	298.5
Noncontrolling interests	0	0
Total liabilities and equity	817.1	320.7
Senior Notes [Member] \| Non-Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	50.2	52.2	61.9	54.1
Receivables, net	103	82
Affiliated receivables	1.3	2.3
Inventories, net	102.6	82.9
Deferred tax assets	1.5	0.6
Other current assets	34.6	37.3
Total current assets	293.2	257.3
Equity investments	3.6	4.6
Property, plant and equipment, net	135.4	84.8
Goodwill	57.5	32.9
Intangible assets, net	37.4
Deferred tax assets		8.3
Deferred tax assets	7.7
Affiliated loan receivables	40.9	40.9
Other noncurrent assets	0.9	11.2
Total assets	576.6	440
LIABILITIES AND EQUITY
Accounts payable	50.6	52.6
Affiliated payables	13.5	8.6
Accrued liabilities	55	54.1
Short-term debt and current portion of long-term debt	13.9
Total current liabilities	133	115.3
Long-term debt	42.6	6.6
Affiliated debt	112	55.2
Other long-term liabilities	35
Other long-term liabilities		26.8
Total liabilities	322.6	203.9
Koppers shareholders' equity	240.1	216.1
Noncontrolling interests	13.9	20
Total liabilities and equity	$576.60	$440

Subsidiary_Guarantor_Informati5

Subsidiary Guarantor Information for Koppers Inc. Senior Notes - Condensed Consolidating Statement of Cash Flows (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Subsidiary, Sale of Stock [Line Items]
Cash provided by (used in) operating activities	$35.50	$117.60	$77.80
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions	-83.8	-72.9	-28.9
Loan repayment by related party	0	0	2.2
Net cash proceeds (payments) from divestitures and asset sales	0.3	2.9	0.8
Net cash used in investing activities	-580	-72.3	-39.9
Capital expenditures and acquisitions	-83.8	-72.9	-28.9
Net cash proceeds (payments) from divestitures and asset sales	0.3	2.9	0.8
Net cash used in investing activities	-580	-72.3	-39.9
Cash provided by (used in) financing activities:
Deferred financing costs	-11.1	-1.3	-0.1
Dividends paid	-20.4	-21.1	-19.5
Net cash provided by (used in) financing activities	516.1	-30.3	-27.3
Effect of exchange rates on cash	-2.7	0.5	2
Net increase in cash and cash equivalents	-31.1	15.5	12.6
Cash and cash equivalents at beginning of year	82.2	66.7	54.1
Cash and cash equivalents at end of period	51.1	82.2	66.7
Deferred financing costs	-11.1	-1.3	-0.1
Dividends paid	-20.4	-21.1	-19.5
Net cash provided by (used in) financing activities	516.1	-30.3	-27.3
Effect of exchange rates on cash	-2.7	0.5	2
Net increase (decrease) in cash and cash equivalents	-31.1	15.5	12.6
Cash and cash equivalents at beginning of year	82.2	66.7	54.1
Cash and cash equivalents at end of period	51.1	82.2	66.7
Senior Notes [Member]
Subsidiary, Sale of Stock [Line Items]
Cash provided by (used in) operating activities	35.5	117.6	77.8
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions	-580.3	-75.2	-42.9
Loan repayment by related party			2.2
(Loans to) repayments from affiliates	0	0	0
Net cash proceeds (payments) from divestitures and asset sales	0.3	2.9	0.8
Net cash used in investing activities	-580	-72.3	-39.9
Capital expenditures and acquisitions	-580.3	-75.2	-42.9
(Loans to) repayments from affiliates	0	0	0
Net cash proceeds (payments) from divestitures and asset sales	0.3	2.9	0.8
Net cash used in investing activities	-580	-72.3	-39.9
Cash provided by (used in) financing activities:
Repayments of long-term debt	547.5	6.6	-6.4
Borrowings of affiliated long-term debt	0	0	0
Deferred financing costs	-11.1	-1.3	-0.1
Dividends paid	-20.4	-21.1	-19.5
Stock issued and repurchased	-1.3	-17.3	-6.6
Other financing receipts	1.4	2.8	5.3
Net cash provided by (used in) financing activities	516.1	-30.3	-27.3
Effect of exchange rates on cash	-2.7	0.5	2
Net increase in cash and cash equivalents	-31.1	15.5	12.6
Cash and cash equivalents at beginning of year	82.2	66.7	54.1
Cash and cash equivalents at end of period	51.1	82.2	66.7
Borrowings (repayments) of long-term debt	547.5	6.6	-6.4
Borrowings (repayments) of affiliated debt	0	0	0
Deferred financing costs	-11.1	-1.3	-0.1
Other financing activities	1.4	2.8	5.3
Dividends paid	-20.4	-21.1	-19.5
Stock issued (repurchased)	-1.3	-17.3	-6.6
Net cash provided by (used in) financing activities	516.1	-30.3	-27.3
Effect of exchange rates on cash	-2.7	0.5	2
Net increase (decrease) in cash and cash equivalents	-31.1	15.5	12.6
Cash and cash equivalents at beginning of year	82.2	66.7	54.1
Cash and cash equivalents at end of period	51.1	82.2	66.7
Senior Notes [Member] \| Intersegment [Member]
Subsidiary, Sale of Stock [Line Items]
Cash provided by (used in) operating activities	-54.3	-376.6	-32.5
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions	14.8	0	0
Loan repayment by related party			0
(Loans to) repayments from affiliates	71.1	-190.7	10.8
Net cash proceeds (payments) from divestitures and asset sales	0	0	0
Net cash used in investing activities	85.9	-190.7	10.8
Capital expenditures and acquisitions	14.8	0	0
(Loans to) repayments from affiliates	71.1	-190.7	10.8
Net cash proceeds (payments) from divestitures and asset sales	0	0	0
Net cash used in investing activities	85.9	-190.7	10.8
Cash provided by (used in) financing activities:
Repayments of long-term debt	0	0	0
Borrowings of affiliated long-term debt	-71.1	190.7	-10.8
Deferred financing costs	0	0	0
Dividends paid	54.3	376.6	32.5
Stock issued and repurchased	-14.8	0	0
Other financing receipts	0	0	0
Net cash provided by (used in) financing activities	-31.6	567.3	21.7
Effect of exchange rates on cash	0	0	0
Net increase in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of period	0	0	0
Borrowings (repayments) of long-term debt	0	0	0
Borrowings (repayments) of affiliated debt	-71.1	190.7	-10.8
Deferred financing costs	0	0	0
Other financing activities	0	0	0
Dividends paid	54.3	376.6	32.5
Stock issued (repurchased)	-14.8	0	0
Net cash provided by (used in) financing activities	-31.6	567.3	21.7
Effect of exchange rates on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of period	0	0	0
Senior Notes [Member] \| Parent [Member]
Subsidiary, Sale of Stock [Line Items]
Cash provided by (used in) operating activities	21.8	37.8	26.1
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions	0	0	0
Loan repayment by related party			0
(Loans to) repayments from affiliates	0	0	0
Net cash proceeds (payments) from divestitures and asset sales	0	0	0
Net cash used in investing activities	0	0	0
Capital expenditures and acquisitions	0	0	0
(Loans to) repayments from affiliates	0	0	0
Net cash proceeds (payments) from divestitures and asset sales	0	0	0
Net cash used in investing activities	0	0	0
Cash provided by (used in) financing activities:
Repayments of long-term debt	0	0	0
Borrowings of affiliated long-term debt	0	0	0
Deferred financing costs	0	0	0
Dividends paid	-20.5	-20.5	-19.5
Stock issued and repurchased	-1.3	-17.3	-6.6
Other financing receipts	0	0	0
Net cash provided by (used in) financing activities	-21.8	-37.8	-26.1
Effect of exchange rates on cash	0	0	0
Net increase in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of period	0	0	0
Borrowings (repayments) of long-term debt	0	0	0
Borrowings (repayments) of affiliated debt	0	0	0
Deferred financing costs	0	0	0
Other financing activities	0	0	0
Dividends paid	-20.5	-20.5	-19.5
Stock issued (repurchased)	-1.3	-17.3	-6.6
Net cash provided by (used in) financing activities	-21.8	-37.8	-26.1
Effect of exchange rates on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of period	0	0	0
Senior Notes [Member] \| Koppers Inc. [Member]
Subsidiary, Sale of Stock [Line Items]
Cash provided by (used in) operating activities	23.8	278.7	44.6
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions	-518.5	-23.3	-21.3
Loan repayment by related party			0
(Loans to) repayments from affiliates	-32.2	-0.8	0.3
Net cash proceeds (payments) from divestitures and asset sales	0.1	1.3	0.4
Net cash used in investing activities	-550.6	-22.8	-20.6
Capital expenditures and acquisitions	-518.5	-23.3	-21.3
(Loans to) repayments from affiliates	-32.2	-0.8	0.3
Net cash proceeds (payments) from divestitures and asset sales	0.1	1.3	0.4
Net cash used in investing activities	-550.6	-22.8	-20.6
Cash provided by (used in) financing activities:
Repayments of long-term debt	497	0	-6.4
Borrowings of affiliated long-term debt	35.8	-191.5	13.3
Deferred financing costs	-11.1	-1.3	-0.1
Dividends paid	-23.6	-38.5	-27.6
Stock issued and repurchased	0	0	0
Other financing receipts	0	0.5	1.6
Net cash provided by (used in) financing activities	498.1	-230.8	-19.2
Effect of exchange rates on cash	-1.2	0	0
Net increase in cash and cash equivalents	-29.9	25.1	4.8
Cash and cash equivalents at beginning of year	29.9	4.8	0
Cash and cash equivalents at end of period	0	29.9	4.8
Borrowings (repayments) of long-term debt	497	0	-6.4
Borrowings (repayments) of affiliated debt	35.8	-191.5	13.3
Deferred financing costs	-11.1	-1.3	-0.1
Other financing activities	0	0.5	1.6
Dividends paid	-23.6	-38.5	-27.6
Stock issued (repurchased)	0	0	0
Net cash provided by (used in) financing activities	498.1	-230.8	-19.2
Effect of exchange rates on cash	-1.2	0	0
Net increase (decrease) in cash and cash equivalents	-29.9	25.1	4.8
Cash and cash equivalents at beginning of year	29.9	4.8	0
Cash and cash equivalents at end of period	0	29.9	4.8
Senior Notes [Member] \| Domestic Guarantor Subsidiaries [Member]
Subsidiary, Sale of Stock [Line Items]
Cash provided by (used in) operating activities	34.7	130.1	8.7
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions	-16.7	0	0
Loan repayment by related party			0
(Loans to) repayments from affiliates	-38.9	193.2	-8.4
Net cash proceeds (payments) from divestitures and asset sales	0.1	0	0
Net cash used in investing activities	-55.5	193.2	-8.4
Capital expenditures and acquisitions	-16.7	0	0
(Loans to) repayments from affiliates	-38.9	193.2	-8.4
Net cash proceeds (payments) from divestitures and asset sales	0.1	0	0
Net cash used in investing activities	-55.5	193.2	-8.4
Cash provided by (used in) financing activities:
Repayments of long-term debt	0	0	0
Borrowings of affiliated long-term debt	27.6	0.8	-0.3
Deferred financing costs	0	0	0
Dividends paid	-6.1	-324	0
Stock issued and repurchased	0	0	0
Other financing receipts	0	0	0
Net cash provided by (used in) financing activities	21.5	-323.2	-0.3
Effect of exchange rates on cash	1	0	0
Net increase in cash and cash equivalents	1.7	0.1	0
Cash and cash equivalents at beginning of year	0.1	0	0
Cash and cash equivalents at end of period	0.9	0.1	0
Borrowings (repayments) of long-term debt	0	0	0
Borrowings (repayments) of affiliated debt	27.6	0.8	-0.3
Deferred financing costs	0	0	0
Other financing activities	0	0	0
Dividends paid	-6.1	-324	0
Stock issued (repurchased)	0	0	0
Net cash provided by (used in) financing activities	21.5	-323.2	-0.3
Effect of exchange rates on cash	1	0	0
Net increase (decrease) in cash and cash equivalents	1.7	0.1	0
Cash and cash equivalents at beginning of year	0.1	0	0
Cash and cash equivalents at end of period	0.9	0.1	0
Senior Notes [Member] \| Non-Guarantor Subsidiaries [Member]
Subsidiary, Sale of Stock [Line Items]
Cash provided by (used in) operating activities	9.5	47.6	30.9
Cash provided by (used in) investing activities:
Capital expenditures and acquisitions	-59.9	-51.9	-21.6
Loan repayment by related party			2.2
(Loans to) repayments from affiliates	0	-1.7	-2.7
Net cash proceeds (payments) from divestitures and asset sales	0.1	1.6	0.4
Net cash used in investing activities	-59.8	-52	-21.7
Capital expenditures and acquisitions	-59.9	-51.9	-21.6
(Loans to) repayments from affiliates	0	-1.7	-2.7
Net cash proceeds (payments) from divestitures and asset sales	0.1	1.6	0.4
Net cash used in investing activities	-59.8	-52	-21.7
Cash provided by (used in) financing activities:
Repayments of long-term debt	50.5	6.6	0
Borrowings of affiliated long-term debt	7.7	0	-2.2
Deferred financing costs	0	0	0
Dividends paid	-24.5	-14.7	-4.9
Stock issued and repurchased	14.8	0	0
Other financing receipts	1.4	2.3	3.7
Net cash provided by (used in) financing activities	49.9	-5.8	-3.4
Effect of exchange rates on cash	-2.5	0.5	2
Net increase in cash and cash equivalents	-2.9	-9.7	7.8
Cash and cash equivalents at beginning of year	52.2	61.9	54.1
Cash and cash equivalents at end of period	50.2	52.2	61.9
Borrowings (repayments) of long-term debt	50.5	6.6	0
Borrowings (repayments) of affiliated debt	7.7	0	-2.2
Deferred financing costs	0	0	0
Other financing activities	1.4	2.3	3.7
Dividends paid	-24.5	-14.7	-4.9
Stock issued (repurchased)	14.8	0	0
Net cash provided by (used in) financing activities	49.9	-5.8	-3.4
Effect of exchange rates on cash	-2.5	0.5	2
Net increase (decrease) in cash and cash equivalents	-2.9	-9.7	7.8
Cash and cash equivalents at beginning of year	52.2	61.9	54.1
Cash and cash equivalents at end of period	$50.20	$52.20	$61.90

Schedule_II_Valuation_and_Qual1

Schedule II - Valuation and Qualifying Accounts (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$3.60	$3.70	$0.30
Business Acquisition	2.6	0	0
Increase (Decrease) to Expense	-0.2	-0.2	3.2
Net (Write- Offs) Recoveries	0	0	0
Currency Translation	-0.4	0.1	0.2
Balance at End of Year	5.6	3.6	3.7
Inventory Obsolescence Reserves [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	1.7	1.1	1.4
Business Acquisition	0.8	0	0
Increase (Decrease) to Expense	1	0.7	0.5
Net (Write- Offs) Recoveries	0	0	-0.8
Currency Translation	-0.1	-0.1	0
Balance at End of Year	3.4	1.7	1.1
Deferred Tax Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	19.7	17.4	10.2
Business Acquisition	1.5	0	0
Increase (Decrease) to Expense	11.4	2.6	8.8
Net (Write- Offs) Recoveries	0	-0.2	-1.6
Currency Translation	-0.2	-0.1	0
Balance at End of Year	$32.40	$19.70	$17.40