Cover - shares	9 Months Ended
	Sep. 30, 2020	Oct. 31, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	1-38300
Entity Registrant Name	CANNAE HOLDINGS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-1273460
Entity Address, Address Line One	1701 Village Center Circle,
Entity Address, City or Town	Las Vegas,
Entity Address, State or Province	NV
Entity Address, Postal Zip Code	89134
City Area Code	702
Local Phone Number	323-7330
Title of 12(b) Security	Cannae Common Stock, $0.0001 par value
Trading Symbol	CNNE
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		91,656,245
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001704720
Current Fiscal Year End Date	--12-31