Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Jan. 25, 2021	Jun. 30, 2020
Document and Entity Information [Abstract]
Document Type	10-K
Document Fiscal Period Focus	FY
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Amendment Flag	false
Document Fiscal Year Focus	2020
Current Fiscal Year End Date	--12-31
Entity File Number	1-16411
Entity Registrant Name	NORTHROP GRUMMAN CORP /DE/
Entity Central Index Key	0001133421
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	80-0640649
Entity Address, Address Line One	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
Title of 12(b) Security	Common Stock
Trading Symbol	NOC
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 51.2
Entity Common Stock, Shares Outstanding		166,718,384
Documents Incorporated by Reference	Portions of Northrop Grumman Corporation’s Proxy Statement to be filed with the Securities and Exchange Commission pursuant to Regulation 14A for the 2021 Annual Meeting of Shareholders are incorporated by reference in Part III of this Form 10-K.