Business and Summary of Significant Accounting Policies (Policies)	3 Months Ended
Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated balance sheet data as of March 31, 2024, was derived from the March 31, 2024, audited financial statements but does not include all disclosures required by U.S. GAAP. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with our audited consolidated financial statements and accompanying notes in our 2024 Form 10-K. Management believes that all adjustments necessary for the fair statement of results, consisting of normally recurring items, have been included in the unaudited condensed consolidated financial statements for the interim periods presented.
Consolidation Policy	Consolidation Policy Our condensed consolidated financial statements have been prepared in accordance with U.S. GAAP and include the assets, liabilities, revenues, and expenses of all wholly owned subsidiaries, majority-owned subsidiaries over which we exercise control, and entities in which we have a controlling financial interest or are deemed to be the primary beneficiary. We eliminate intercompany accounts and transactions from our condensed consolidated financial statements. We use the equity method to account for our investments in entities that we do not control but have the ability to exercise significant influence over operating and financial policies. Consolidated net income attributable to our common shareholder includes our share of the net income (loss) of these entities. The difference between consolidation and the equity method impacts certain of our financial ratios because of the presentation of the detailed line items reported in the condensed consolidated financial statements for consolidated entities, compared to a two-line presentation of investment in and advances to non-consolidated affiliates and equity in net income of non-consolidated affiliates.
Restructuring Activities	Restructuring Activities Restructuring charges, which are recorded within restructuring and impairment expenses, net on our condensed consolidated statements of operations, include employee severance and benefit costs, impairments or accelerated depreciation of certain long-lived assets, and other costs associated with exit activities. In March 2024, the Company approved the plan to close the cold rolling and finishing plant in Buckhannon, West Virginia. The plant ceased substantially all operations in June 2024. As a result, in the first quarter of fiscal 2025, the Company recorded approximately $18 million in charges for restructuring activities related to the plant closure, which consisted primarily of charges for accelerated depreciation and employee-related restructuring expenses.
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of our condensed consolidated financial statements in accordance with U.S. GAAP requires us to make estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities, the disclosures of contingent assets and liabilities as of the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. The principal areas of judgment relate to (1) impairment of goodwill; (2) actuarial assumptions related to pension and other postretirement benefit plans; (3) tax uncertainties and valuation allowances; and (4) assessment of loss contingencies, including environmental and litigation liabilities. Future events and their effects cannot be predicted with certainty, and accordingly, our accounting estimates require the exercise of judgment. The accounting estimates used in the preparation of our condensed consolidated financial statements may change as new events occur, more experience is acquired, additional information is obtained, and our operating environment changes. We evaluate and update our assumptions and estimates on an ongoing basis and may employ outside experts to assist in our evaluations. Actual results could differ from the estimates we have used.
Recently Adopted Accounting Standards and Recently Issued Accounting Standards (Not Yet Adopted)	Recently Adopted Accounting Standards In September 2022, the FASB issued ASU 2022-04, Liabilities—Supplier Finance Programs (Topic 405-50): Disclosure of Supplier Finance Program Obligations ("ASU 2022-04"). This ASU requires a buyer in a supplier finance program to disclose qualitative and quantitative information about its supplier finance programs, including the key terms of the program, the amount of obligations outstanding at the end of the reporting period, and a description of where those obligations are presented in the balance sheet. On April 1, 2023, the Company adopted ASU 2022-04, except for the amendment on roll-forward information, which is effective for fiscal years beginning after December 15, 2023. The adoption of this guidance resulted in enhanced disclosures regarding these programs (see Supplier Finance Programs above) and did not have a material impact on our consolidated financial condition, results of operations, or cash flows. We did not adopt any new accounting pronouncements during the three months ended June 30, 2024, that had a material impact on our consolidated financial condition, results of operations, or cash flows. Recently Issued Accounting Standards (Not Yet Adopted) In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. This ASU updates reportable segment disclosure requirements primarily through enhanced disclosures about significant segment expenses. This ASU is effective for all entities for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The amendments should be applied retrospectively to all prior periods presented in the financial statements. We are currently evaluating this ASU to determine its impact on the Company's disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. This ASU expands disclosures in an entity's income tax rate reconciliation table and disclosures regarding cash taxes paid both in the U.S. and foreign jurisdictions. This ASU is effective for all entities for fiscal years beginning after December 15, 2024. We are currently evaluating this ASU to determine its impact on the Company's disclosures. There are no other recent accounting pronouncements pending adoption that we expect will have a material impact on our consolidated financial condition, results of operations, or cash flows.

Business and Summary of Significant Accounting Policies (Policies)

3 Months Ended

Jun. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The condensed consolidated balance sheet data as of March 31, 2024, was derived from the March 31, 2024, audited financial statements but does not include all disclosures required by U.S. GAAP. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with our audited consolidated financial statements and accompanying notes in our 2024 Form 10-K. Management believes that all adjustments necessary for the fair statement of results, consisting of normally recurring items, have been included in the unaudited condensed consolidated financial statements for the interim periods presented.

Consolidation Policy

Our condensed consolidated financial statements have been prepared in accordance with U.S. GAAP and include the assets, liabilities, revenues, and expenses of all wholly owned subsidiaries, majority-owned subsidiaries over which we exercise control, and entities in which we have a controlling financial interest or are deemed to be the primary beneficiary. We eliminate intercompany accounts and transactions from our condensed consolidated financial statements.

We use the equity method to account for our investments in entities that we do not control but have the ability to exercise significant influence over operating and financial policies. Consolidated net income attributable to our common shareholder includes our share of the net income (loss) of these entities. The difference between consolidation and the equity method impacts certain of our financial ratios because of the presentation of the detailed line items reported in the condensed consolidated financial statements for consolidated entities, compared to a two-line presentation of investment in and advances to non-consolidated affiliates and equity in net income of non-consolidated affiliates.

Restructuring Activities

Restructuring charges, which are recorded within restructuring and impairment expenses, net on our condensed consolidated statements of operations, include employee severance and benefit costs, impairments or accelerated depreciation of certain long-lived assets, and other costs associated with exit activities. In March 2024, the Company approved the plan to close the cold rolling and finishing plant in Buckhannon, West Virginia. The plant ceased substantially all operations in June 2024. As a result, in the first quarter of fiscal 2025, the Company recorded approximately $18 million in charges for restructuring activities related to the plant closure, which consisted primarily of charges for accelerated depreciation and employee-related restructuring expenses.

Use of Estimates and Assumptions

The preparation of our condensed consolidated financial statements in accordance with U.S. GAAP requires us to make estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities, the disclosures of contingent assets and liabilities as of the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. The principal areas of judgment relate to (1) impairment of goodwill; (2) actuarial assumptions related to pension and other postretirement benefit plans; (3) tax uncertainties and valuation allowances; and (4) assessment of loss contingencies, including environmental and litigation liabilities. Future events and their effects cannot be predicted with certainty, and accordingly, our accounting estimates require the exercise of judgment. The accounting estimates used in the preparation of our condensed consolidated financial statements may change as new events occur, more experience is acquired, additional information is obtained, and our operating environment changes. We evaluate and update our assumptions and estimates on an ongoing basis and may employ outside experts to assist in our evaluations. Actual results could differ from the estimates we have used.

Recently Adopted Accounting Standards and Recently Issued Accounting Standards (Not Yet Adopted)

Recently Adopted Accounting Standards

In September 2022, the FASB issued ASU 2022-04, Liabilities—Supplier Finance Programs (Topic 405-50): Disclosure of Supplier Finance Program Obligations ("ASU 2022-04"). This ASU requires a buyer in a supplier finance program to disclose qualitative and quantitative information about its supplier finance programs, including the key terms of the program, the amount of obligations outstanding at the end of the reporting period, and a description of where those obligations are presented in the balance sheet. On April 1, 2023, the Company adopted ASU 2022-04, except for the amendment on roll-forward information, which is effective for fiscal years beginning after December 15, 2023. The adoption of this guidance resulted in enhanced disclosures regarding these programs (see Supplier Finance Programs above) and did not have a material impact on our consolidated financial condition, results of operations, or cash flows.

We did not adopt any new accounting pronouncements during the three months ended June 30, 2024, that had a material impact on our consolidated financial condition, results of operations, or cash flows.

Recently Issued Accounting Standards (Not Yet Adopted)

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. This ASU updates reportable segment disclosure requirements primarily through enhanced disclosures about significant segment expenses. This ASU is effective for all entities for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The amendments should be applied retrospectively to all prior periods presented in the financial statements. We are currently evaluating this ASU to determine its impact on the Company's disclosures.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. This ASU expands disclosures in an entity's income tax rate reconciliation table and disclosures regarding cash taxes paid both in the U.S. and foreign jurisdictions. This ASU is effective for all entities for fiscal years beginning after December 15, 2024. We are currently evaluating this ASU to determine its impact on the Company's disclosures.

There are no other recent accounting pronouncements pending adoption that we expect will have a material impact on our consolidated financial condition, results of operations, or cash flows.