v3.26.1
Cover Page - shares
 3 Months Ended
Mar. 31, 2026
Apr. 27, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 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 Q1  
Document Fiscal Year Focus 2026  
Amendment Flag false  
Class A Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   94,895,913
Class B Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   43,435,000