Basis of Presentation (Policies)	9 Months Ended
Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation	Principles of Consolidation - The unaudited condensed consolidated financial statements of HII and its subsidiaries have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and the instructions to Form 10-Q promulgated by the Securities and Exchange Commission ("SEC"). As used in the Notes to the Condensed Consolidated Financial Statements (Unaudited), the terms "HII" and "the Company" refer to HII and its subsidiaries. All intercompany transactions and balances are eliminated in consolidation. For classification of current assets and liabilities related to its long-term production contracts, the Company uses the duration of these contracts as its operating cycle, which is generally longer than one year. Additionally, certain prior year amounts have been reclassified to conform to the current year presentation. These unaudited condensed consolidated financial statements include all adjustments of a normal recurring nature considered necessary by management for a fair presentation of the unaudited condensed consolidated financial position, results of operations, and cash flows and should be read in conjunction with the Company's audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2023 (the "2023 Annual Report on Form 10-K").
Fiscal Period Policy	The quarterly information is labeled using a calendar convention; that is, first quarter is consistently labeled as ending on March 31, second quarter as ending on June 30, and third quarter as ending on September 30. It is management's long-standing practice to establish interim closing dates using a "fiscal" calendar, which requires the businesses to close their books on a Friday near these quarter-end dates in order to normalize the potentially disruptive effects of quarterly closings on business processes. This practice only exists for interim periods within a reporting year.
Accounting Estimates	Accounting Estimates - The preparation of the Company's unaudited condensed consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets and liabilities and the disclosure of contingencies at 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 those estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments - Except for the Company's long-term debt, the carrying amounts of the Company's financial instruments that are recorded at historical cost approximate fair value due to the short-term nature of the instruments and low credit risk associated with the respective counterparties. The Company maintains multiple grantor trusts to fund certain non-qualified pension plans. These trusts were valued at $235 million and $220 million as of September 30, 2024, and December 31, 2023, respectively, and are presented within miscellaneous other assets within the unaudited condensed consolidated statements of financial position. These trusts consist primarily of investments in marketable securities, which are held at fair value within Level 1 of the fair value hierarchy. The estimated fair values of the Company's total long-term debt (including current portion), excluding finance lease liabilities, as of September 30, 2024, and December 31, 2023, were $2,146 million and $2,309 million, respectively. The estimated fair values of the current portion of the Company's long-term debt, excluding finance lease liabilities, were $496 million and $229 million as of September 30, 2024, and December 31, 2023, respectively. The fair values of the Company's long-term debt were calculated based on recent trades of the Company's debt instruments in inactive markets, which fall within Level 2 of the fair value hierarchy.
Debt Policy	Debt – In September 2024, the Company amended and restated its existing $1.5 billion credit facility, increasing the capacity thereunder to $1.7 billion and extending the maturity date for five years from signing (the “Second Amended and Restated Revolving Credit Facility”). The Second Amended and Restated Revolving Credit Facility has a variable interest rate on outstanding borrowings based on the Secured Overnight Financing Rate (“SOFR”) plus an interest spread based upon the Company’s credit rating, which may vary between 1.225% and 2.100%. The Second Amended and Restated Revolving Credit Facility also has a commitment fee on unutilized amounts based on the Company’s credit rating, which may vary between 0.125% and 0.300%. The Second Amended and Restated Revolving Credit Facility includes a letter of credit sub-facility of $300 million. As of September 30, 2024, the Company had not drawn on the Second Amended and Restated Revolving Credit Facility. Based on the Company’s current credit rating, the interest rate spread on drawn amounts would be 1.475% and the commitment fee would be 0.200%. The Second Amended and Restated Revolving Credit Facility contains customary affirmative and negative covenants and events of default, as well as a financial covenant based on a maximum total leverage ratio. Each of the Company's existing and future material wholly owned domestic subsidiaries, except those that are specifically designated as unrestricted subsidiaries, are and will be guarantors under the Second Amended and Restated Revolving Credit Facility. Additionally, in September 2024, the Company's borrowing capacity under its commercial paper program increased from $1 billion to $1.7 billion.

Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Principles of Consolidation - The unaudited condensed consolidated financial statements of HII and its subsidiaries have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and the instructions to Form 10-Q promulgated by the Securities and Exchange Commission ("SEC"). As used in the Notes to the Condensed Consolidated Financial Statements (Unaudited), the terms "HII" and "the Company" refer to HII and its subsidiaries. All intercompany transactions and balances are eliminated in consolidation. For classification of current assets and liabilities related to its long-term production contracts, the Company uses the duration of these contracts as its operating cycle, which is generally longer than one year. Additionally, certain prior year amounts have been reclassified to conform to the current year presentation.

These unaudited condensed consolidated financial statements include all adjustments of a normal recurring nature considered necessary by management for a fair presentation of the unaudited condensed consolidated financial position, results of operations, and cash flows and should be read in conjunction with the Company's audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2023 (the "2023 Annual Report on Form 10-K").

Fiscal Period Policy

The quarterly information is labeled using a calendar convention; that is, first quarter is consistently labeled as ending on March 31, second quarter as ending on June 30, and third quarter as ending on September 30. It is management's long-standing practice to establish interim closing dates using a "fiscal" calendar, which requires the businesses to close their books on a Friday near these quarter-end dates in order to normalize the potentially disruptive effects of quarterly closings on business processes. This practice only exists for interim periods within a reporting year.

Accounting Estimates

Accounting Estimates - The preparation of the Company's unaudited condensed consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets and liabilities and the disclosure of contingencies at 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 those estimates.

Fair Value of Financial Instruments

Fair Value of Financial Instruments - Except for the Company's long-term debt, the carrying amounts of the Company's financial instruments that are recorded at historical cost approximate fair value due to the short-term nature of the instruments and low credit risk associated with the respective counterparties.

The Company maintains multiple grantor trusts to fund certain non-qualified pension plans. These trusts were valued at $235 million and $220 million as of September 30, 2024, and December 31, 2023, respectively, and are presented within miscellaneous other assets within the unaudited condensed consolidated statements of financial position. These trusts consist primarily of investments in marketable securities, which are held at fair value within Level 1 of the fair value hierarchy.

The estimated fair values of the Company's total long-term debt (including current portion), excluding finance lease liabilities, as of September 30, 2024, and December 31, 2023, were $2,146 million and $2,309 million, respectively. The estimated fair values of the current portion of the Company's long-term debt, excluding finance lease liabilities, were $496 million and $229 million as of September 30, 2024, and December 31, 2023, respectively. The fair values of the Company's long-term debt were calculated based on recent trades of the Company's debt instruments in inactive markets, which fall within Level 2 of the fair value hierarchy.

Debt Policy

Debt – In September 2024, the Company amended and restated its existing $1.5 billion credit facility, increasing the capacity thereunder to $1.7 billion and extending the maturity date for five years from signing (the “Second Amended and Restated Revolving Credit Facility”). The Second Amended and Restated Revolving Credit Facility has a variable interest rate on outstanding borrowings based on the Secured Overnight Financing Rate (“SOFR”) plus an interest spread based upon the Company’s credit rating, which may vary between 1.225% and 2.100%. The Second Amended and Restated Revolving Credit Facility also has a commitment fee on unutilized amounts based on the Company’s credit rating, which may vary between 0.125% and 0.300%. The Second Amended and Restated Revolving Credit Facility includes a letter of credit sub-facility of $300 million.

As of September 30, 2024, the Company had not drawn on the Second Amended and Restated Revolving Credit Facility. Based on the Company’s current credit rating, the interest rate spread on drawn amounts would be 1.475% and the commitment fee would be 0.200%.

The Second Amended and Restated Revolving Credit Facility contains customary affirmative and negative covenants and events of default, as well as a financial covenant based on a maximum total leverage ratio. Each of the Company's existing and future material wholly owned domestic subsidiaries, except those that are specifically designated as unrestricted subsidiaries, are and will be guarantors under the Second Amended and Restated Revolving Credit Facility.

Additionally, in September 2024, the Company's borrowing capacity under its commercial paper program increased from $1 billion to $1.7 billion.