Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2025	Nov. 03, 2025
Entity Information [Line Items]
Entity Registrant Name	NextNav Inc.
Document Type	10-Q
Amendment Flag	false
Entity Central Index Key	0001865631
Document Period End Date	Sep. 30, 2025
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q3
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-40985
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	87-0854654
Entity Address, Address Line One	11911 Freedom Dr.
Entity Address, Address Line Two	Ste. 200
Entity Address, City or Town	Reston
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	20190
City Area Code	800
Local Phone Number	775-0982
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		134,829,088
Common Stock, par value $0.0001 per share
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	NN
Security Exchange Name	NASDAQ
Warrants, each to purchase one share of Common Stock
Entity Information [Line Items]
Title of 12(b) Security	Warrants, each to purchase one share of Common Stock
Trading Symbol	NNAVW
Security Exchange Name	NASDAQ