| Document and Entity Information | Aug. 19, 2021 |
| Cover [Abstract] | |
| Amendment Flag | true |
| Entity Central Index Key | 0001501585 |
| Document Type | 8-K/A |
| Document Period End Date | Aug. 19, 2021 |
| Entity Registrant Name | HUNTINGTON INGALLS INDUSTRIES, INC. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-34910 |
| Entity Tax Identification Number | 90-0607005 |
| Entity Address, Address Line One | 4101 Washington Avenue |
| Entity Address, City or Town | Newport News |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 23607 |
| City Area Code | (757) |
| Local Phone Number | 380-2000 |
| Security 12b Title | Common Stock |
| Trading Symbol | HII |
| Security Exchange Name | NYSE |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Description | This Current Report on Form 8-K/A amends the Initial 8-K to include the historical audited financial statements and unaudited interim financial statements of Alion and the pro forma combined financial information required by Items 9.01(a) and 9.01(b) of Form 8-K and should be read in conjunction with the Initial 8-K. |
