v3.26.3
Stockholders' Equity - Schedule of Other Ownership Interests (Details) - shares
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Class of Stock [Roll Forward]          
Ending balance (in shares) 347,066,915 346,042,267 347,066,915 346,042,267  
Common stock, shares, issued (in shares) 347,066,915 346,042,267 347,066,915 346,042,267  
THG units held by Hagerty, Inc.          
Class of Stock [Roll Forward]          
Beginning of period 29.40% 26.20% 29.10% 26.10%  
End of period 34.70% 29.00% 34.70% 29.00%  
THG units held by other unit holders          
Class of Stock [Roll Forward]          
Beginning balance (in shares) 244,996,392 255,100,044 245,420,794 255,178,346  
Ending balance (in shares) 226,497,481 245,615,794 226,497,481 245,615,794  
Beginning of period 70.60% 73.80% 70.90% 73.90%  
End of period 65.30% 71.00% 65.30% 71.00%  
Class A Common Stock          
Class of Stock [Roll Forward]          
Beginning balance (in shares)     100,706,893    
Ending balance (in shares) 120,569,434   120,569,434    
Common stock, shares, issued (in shares) 120,569,434   120,569,434   100,706,893
Class A Common Stock | THG units held by Hagerty, Inc.          
Class of Stock [Roll Forward]          
Beginning balance (in shares) 101,804,938 90,715,648 100,706,893 90,032,391  
Issuance of shares under employee plans (in shares) 265,585 226,575 939,228 831,530  
Exchange of THG units for Class A Common Stock (in shares) (18,498,911) (9,484,250) (18,923,313) (9,562,552)  
Ending balance (in shares) 120,569,434 100,426,473 120,569,434 100,426,473  
Class A Common Stock | THG units held by other unit holders          
Class of Stock [Roll Forward]          
Exchange of THG units for Class A Common Stock (in shares) (18,498,911) (9,484,250) (18,923,313) (9,562,552)