Cover Page - shares	6 Months Ended
	Jun. 30, 2026	Jul. 24, 2026
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2026
Document Transition Report	false
Entity File Number	001-42878
Entity Registrant Name	Neptune Insurance Holdings Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-4189588
Entity Address, Address Line One	400 6th Street S,
Entity Address, Address Line Two	Suite 2
Entity Address, City or Town	St. Petersburg
Entity Address, State or Province	FL
Entity Address, Postal Zip Code	33701
City Area Code	(727)
Local Phone Number	202-4815
Title of 12(b) Security	Class A common stock, $0.00001 par value
Trading Symbol	NP
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Central Index Key	0002067129
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q2
Amendment Flag	false
Document Fiscal Year Focus	2026
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		93,798,090
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		43,435,000