v2.4.0.8
Document and Entity Information
6 Months Ended
Jun. 30, 2014
Aug. 04, 2014
Document and Entity Information [Abstract]    
Entity Registrant Name NMI HOLDINGS, INC.  
Entity Central Index Key 0001547903  
Document Type 10-Q  
Document Period End Date Jun. 30, 2014  
Amendment Flag false  
Document Fiscal Year Focus 2014  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   58,363,334