Basis of Presentation (Policies)	9 Months Ended
Mar. 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, 2015 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, 2015 (the “2015 Form 10-K”). Operating results for the three and nine months ended March 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.
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 April 2015, the FASB issued ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30) Simplifying the Presentation of Debt Issuance Costs. The guidance in ASU 2015-03 requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of a debt discount. The guidance in ASU 2015-03 is required for annual reporting periods beginning after December 15, 2015, including interim periods within the reporting period. Early adoption is permitted for financial statements that have not been previously issued. If adopted as of March 31, 2016, the reclassification impact on the consolidated balance sheets would be $3.0 million from other assets to long-term debt. In August 2015, the FASB issued ASU 2015-15, Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line of Credit Arrangements. This guidance indicates that the guidance in ASU 2015-03 did not address presentation or subsequent measurement of debt issuance costs related to line of credit arrangements. Given the absence of authoritative guidance within ASU 2015-03, the SEC staff has indicated that they would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the costs ratably over the term of the line of credit arrangement, regardless of whether there are any outstanding borrowings on the line of credit arrangement. The Company does not expect the adoption of ASU 2015-15 to have any effect on the consolidated financial statements. In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes, requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as noncurrent on the balance sheet. The classification change for all deferred taxes as noncurrent simplifies entities’ processes as it eliminates the need to separately identify the net current and net noncurrent deferred tax asset or liability in each jurisdiction and allocate valuation allowances. The guidance in ASU 2015-17 is effective for public entities in fiscal years beginning after December 15, 2016, and for interim periods within those fiscal years. ASU 2015-17 can be applied retrospectively or prospectively and early adoption is permitted. The Company is evaluating the impact of the adoption of ASU 2015-17 on the consolidated financial statements. In February 2016, the FASB issued ASU 2016-02 Leases (Topic 842). ASU No. 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 No. 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 No. 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 No. 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 No. 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 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 April 2015, the FASB issued ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30) Simplifying the Presentation of Debt Issuance Costs. The guidance in ASU 2015-03 requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of a debt discount. The guidance in ASU 2015-03 is required for annual reporting periods beginning after December 15, 2015, including interim periods within the reporting period. Early adoption is permitted for financial statements that have not been previously issued. If adopted as of March 31, 2016, the reclassification impact on the consolidated balance sheets would be $3.0 million from other assets to long-term debt.

In August 2015, the FASB issued ASU 2015-15, Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line of Credit Arrangements. This guidance indicates that the guidance in ASU 2015-03 did not address presentation or subsequent measurement of debt issuance costs related to line of credit arrangements. Given the absence of authoritative guidance within ASU 2015-03, the SEC staff has indicated that they would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the costs ratably over the term of the line of credit arrangement, regardless of whether there are any outstanding borrowings on the line of credit arrangement. The Company does not expect the adoption of ASU 2015-15 to have any effect on the consolidated financial statements.

In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes, requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as noncurrent on the balance sheet. The classification change for all deferred taxes as noncurrent simplifies entities’ processes as it eliminates the need to separately identify the net current and net noncurrent deferred tax asset or liability in each jurisdiction and allocate valuation allowances. The guidance in ASU 2015-17 is effective for public entities in fiscal years beginning after December 15, 2016, and for interim periods within those fiscal years. ASU 2015-17 can be applied retrospectively or prospectively and early adoption is permitted. The Company is evaluating the impact of the adoption of ASU 2015-17 on the consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02 Leases (Topic 842). ASU No. 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 No. 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 No. 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 No. 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 No. 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.