CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss		$ 466.1	$ 18.9	$ 1,104.2	$ (1.0)
Other comprehensive earnings (loss), net of tax:
Unrealized gain (loss) on investments and other financial instruments, net (excluding investments in unconsolidated affiliates)	[1]	5.9	0.1	11.2	(0.1)
Unrealized (loss) gain relating to investments in unconsolidated affiliates	[2]	(2.5)	2.3	(6.4)	8.2
Reclassification adjustments for unrealized gains and losses on unconsolidated affiliates, net of tax, included in net earnings	[3]	0.0	4.1	44.3	4.7
Other comprehensive earnings		3.4	6.5	49.1	12.8
Comprehensive earnings		469.5	25.4	1,153.3	11.8
Less: Comprehensive loss attributable to noncontrolling interests		(9.2)	(4.5)	(18.8)	(7.6)
Comprehensive earnings attributable to Cannae Holdings, Inc.		$ 478.7	$ 29.9	$ 1,172.1	$ 19.4

[1] Net of income tax expense (benefit) of $1.6 million and less than $0.1 million for the three months ended June 30, 2020 and 2019, respectively, and $3.0 million and less than $(0.1) million for the six months ended June 30, 2020 and 2019, respectively.

[2] Net of income tax (benefit) expense of $(0.7) million and $0.6 million for the three months ended June 30, 2020 and 2019, respectively, and $(1.7) million and $2.2 million for the six months ended June 30, 2020 and 2019, respectively.

[3] Net of income tax expense of $1.0 million for the three months ended June 30, 2019 and $11.8 million and $1.2 million for the six months ended June 30, 2020 and 2019, respectively.