v3.19.1
Document and Entity Information - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Mar. 13, 2019
Jun. 29, 2018
Document and Entity Information [Abstract]      
Entity Registrant Name NI Holdings, Inc.    
Entity Central Index Key 0001681206    
Current Fiscal Year End Date --12-31    
Entity Filer Category Accelerated Filer    
Entity Small Business true    
Entity Shell Company false    
Entity Emerging Growth Company true    
Entity Ex Transition Period false    
Entity Common Stock, Shares Outstanding   22,209,599  
Document Type 10-K    
Amendment Flag false    
Entity Current Reporting Status Yes    
Entity Public Float     $ 163
Entity Well-known Seasoned Issuer No    
Document Period End Date Dec. 31, 2018    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2018    
Entity Voluntary Filers No