v3.8.0.1
Document And Entity Information - shares
3 Months Ended
Mar. 31, 2018
Apr. 30, 2018
Document and Entity Information [Abstract]    
Document Type 10-Q  
Document Period End Date Mar. 31, 2018  
Amendment Flag false  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q1  
Entity Registrant Name Cannae Holdings, Inc.  
Entity Central Index Key 0001704720  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   70,858,143