v3.25.2
Unrestricted Net Assets - Condensed Financial Information on Financial Position (Parenthetical) (Detail) - $ / shares
 6 Months Ended 12 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Mar. 31, 2025
Condensed Financial Information on Financial Position [Line Items]      
Common stock, par value $ 0.001 $ 0.001  
Common shares authorized 400,000,000 400,000,000  
Common shares issued 95,464,000 55,464,000  
Common shares outstanding 95,464,000 55,464,000  
Stockholders equity reverse stock split 2-for-1    
Northann Corp [Member]      
Condensed Financial Information on Financial Position [Line Items]      
Stockholders equity reverse stock split 2-for-1 2-for-1  
Northann Corp [Member] | Common Stock [Member]      
Condensed Financial Information on Financial Position [Line Items]      
Common stock, par value   $ 0.001 $ 0.001
Common shares authorized   400,000,000 400,000,000
Common shares issued   55,464,000 95,464,000
Common shares outstanding   55,464,000 95,464,000
Series A Preferred Stock [Member]      
Condensed Financial Information on Financial Position [Line Items]      
Preferred stock, par value $ 0.001 $ 0.001  
Preferred shares authorized 100,000,000 100,000,000  
Preferred shares issued 10,000,000 10,000,000  
Preferred shares outstanding 10,000,000 10,000,000  
Series A Preferred Stock [Member] | Northann Corp [Member]      
Condensed Financial Information on Financial Position [Line Items]      
Preferred stock, par value   $ 0.001 $ 0.001
Preferred shares authorized   100,000,000 100,000,000
Preferred shares issued   10,000,000 10,000,000
Preferred shares outstanding     10,000,000