Basis of Presentation (Policies)	6 Months Ended
Basis of Presentation (Policies)	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments, consisting of normal and recurring adjustments, considered necessary for a fair statement of the results are reflected in the interim periods presented. The June 30, 2016 consolidated balance sheet data was derived from audited financial statements, but does not include all of the disclosures required by U.S. generally accepted accounting principles. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and footnotes thereto included in Carpenter’s annual report on Form 10-K for the year ended June 30, 2016 (the “2016 Form 10-K”). Operating results for the three and six months ended December 31, 2016 are not necessarily indicative of the operating results for any future period. As used throughout this report, unless the context requires otherwise, the terms “Carpenter”, the “Company”, “Registrant”, “Issuer”, “we” and “our” refer to Carpenter Technology Corporation.
Earnings per Common Share	The Company calculates basic and diluted earnings per share using the two class method. Under the two class method, earnings are allocated to common stock and participating securities (non-vested restricted shares and units that receive non-forfeitable dividends) according to their participation rights in dividends and undistributed earnings. The earnings available to each class of stock are divided by the weighted average number of outstanding shares for the period in each class. Diluted earnings per share assumes the issuance of common stock for all potentially dilutive share equivalents outstanding.
Inventories	Inventories are valued at the lower of cost or market. Cost for inventories is principally determined using the last-in, first-out (“LIFO”) method. The Company also uses the first-in, first-out (“FIFO”) and average costs methods.
Regulatory Environmental Costs	The Company is subject to various federal, state, local and international environmental laws and regulations relating to pollution, protection of public health and the environment, natural resource damages and occupational safety and health. Although compliance with these laws and regulations may affect the costs of the Company’s operations, compliance costs to date have not been material. The Company has environmental remediation liabilities at some of its owned operating facilities and has been designated as a potentially responsible party (“PRP”) with respect to certain third party Superfund waste-disposal sites and other third party-owned sites. The Company accrues amounts for environmental remediation costs that represent management’s best estimate of the probable and reasonably estimable future costs related to environmental remediation.
Contingencies and Commitments	The Company is defending various routine claims and legal actions that are incidental to its business and common to its operations, including those pertaining to product claims, commercial disputes, patent infringement, employment actions, employee benefits, compliance with domestic and foreign laws, personal injury claims and tax issues. Like many other manufacturing companies in recent years, the Company, from time to time, has been named as a defendant in lawsuits alleging personal injury as a result of exposure to chemicals and substances in the workplace such as asbestos. The Company provides for costs relating to these matters when a loss is probable and the amount of the loss is reasonably estimable. The effect of the outcome of these matters on the Company’s future results of operations and liquidity cannot be predicted because any such effect depends on future results of operations and the amount and timing (both as to recording future charges to operations and cash expenditures) of the resolution of such matters. While it is not feasible to determine the outcome of these matters, management believes that the total liability from these matters will not have a material effect on the Company’s financial position, results of operations or cash flows over the long-term. However, there can be no assurance that an increase in the scope of pending matters or that any future lawsuits, claims, proceedings or investigations will not be material to the Company’s financial position, results of operations or cash flows in a particular future quarter or year.
Fair Value Measurements	The fair value hierarchy has three levels based on the inputs used to determine fair value. Level 1 refers to quoted prices in active markets for identical assets or liabilities. Level 2 refers to observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. Level 3 refers to unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. Currently, the Company does not use Level 1 and 3 inputs.
Fair Value of Financial Instruments	The Company’s derivative financial instruments consist of commodity forward contracts, foreign currency forward contracts and interest rate swaps. These instruments are measured at fair value using the market method valuation technique. The inputs to this technique utilize information related to foreign exchange rates, commodity prices and interest rates published by third party leading financial news and data providers. This is observable data; however, the valuation of these instruments is not based on actual transactions for the same instruments and, as such, they are classified as Level 2. The Company’s use of derivatives and hedging policies are more fully discussed in Note 11. The Company has currently chosen not to elect the fair value option for any items that are not already required to be measured at fair value in accordance with accounting principles generally accepted in the United States of America.
Recent 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). The guidance in ASU 2014-09 requires that an entity should recognize revenue to depict 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. The guidance in ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. In August 2015, the FASB issued ASU 2015-14, which defers the effective date of this guidance by one year. As such, the Company is required to adopt this standard for its interim and annual periods beginning after December 15, 2017. Early adoption is permitted for interim and annual periods beginning after December 15, 2016. The Company is evaluating the impact of the adoption of ASU 2014-09 on the consolidated financial statements. In February 2016, the FASB issued ASU 2016-02 Leases (Topic 842). ASU 2016-02 improves transparency and comparability among companies by recognizing lease assets and lease liabilities on the balance sheet and by disclosing key information about leasing arrangements. ASU 2016-02 is effective for public business entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2018, with early application permitted. The Company is evaluating the impact of the adoption of ASU 2016-02 on the consolidated financial statements. In March 2016, the FASB issued ASU 2016-08 Revenue from Contracts with Customers (Topic 606) - Principal versus Agent Considerations (Reporting Revenue Gross versus Net). ASU 2016-08 requires an entity to determine whether the nature of its promise to provide goods or services to a customer is performed in a principal or agent capacity and to recognize revenue in a gross or net manner based on its principal/agent designation. ASU 2016-08 is effective for public business entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2017, with early application permitted. The Company is evaluating the impact of the adoption of ASU 2016-08 on the consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation — Stock Compensation (Topic 718) - Improvements to Employee Share-Based Payment Accounting, which outlines new provisions intended to simplify various aspects related to accounting for share-based payments and their presentation in the financial statements. ASU 2016-09 is effective for public business entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2016, with early application permitted. The Company is evaluating the impact of the adoption of ASU 2016-09 on the consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments, which outlines new provisions intended to reduce the existing diversity in practice related to accounting for the cash flow and its presentation in the financial statements. ASU 2016-15 is effective for public business entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2017, with early application permitted. The Company is evaluating the impact of the adoption of ASU 2016-15 on the consolidated financial statements. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740) - Intra-Entity Transfers of Assets Other Than Inventory, which outlines updates to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. ASU 2016-16 is effective for public business entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2017, with early application permitted. The Company is evaluating the impact of the adoption of ASU 2016-16 on the consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230) - Restricted Cash, which outlines that a statement of cash flows explains the change during the period in total cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. ASU 2016-18 is effective for public business entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2017, with early application permitted. The Company is evaluating the impact of the adoption of ASU 2016-18 on the consolidated financial statements.