| Document and Entity Information | Feb. 24, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | Huntington Ingalls Inc |
| Entity Incorporation State Country Code | DE |
| Amendment Flag | false |
| Entity Central Index Key | 0001536678 |
| Document Type | 8-K |
| Document Period End Date | Feb. 24, 2020 |
| Entity File Number | 1-34910 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock |
| Trading Symbol | HII |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
