| Document and Entity Information Document | Dec. 07, 2020 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 7, 2020 |
| Entity Registrant Name | NORTHROP GRUMMAN CORP /DE/ |
| Entity Central Index Key | 0001133421 |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-16411 |
| Entity Tax Identification Number | 80-0640649 |
| Entity Address, Address Line 1 | 2980 Fairview Park Drive |
| Entity Address, City or Town | Falls Church |
| Entity Address, State or Province | VA |
| Entity Address, Postal ZIP Code | 22042 |
| City Area Code | 703 |
| Local Phone Number | 280-2900 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-Commencement Tender Offer | false |
| Pre-Commencement Issuer Tender Offer | false |
| Security 12(b) Title | Common Stock |
| Trading Symbol | NOC |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
