Initial Public Offering (IPO) - Narrative (Details) $ / shares in Units, $ in Millions					1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 06, 2020 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 23, 2020 shares	Aug. 08, 2018 USD ($) shares	Feb. 07, 2019 USD ($)	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2019 USD ($)	Dec. 31, 2019 $ / shares shares
Class of Stock [Line Items]
Common stock, par value (USD per share) | $ / shares		$ 0.0001				$ 0.0001		$ 0.0001		$ 0.0001
Gross proceeds from sale of stock				$ 1,028.4
Common stock authorized (shares) | shares		2,000,000,000	2,000,000,000			2,000,000,000		2,000,000,000		2,000,000,000
Preferred stock authorized (shares) | shares			25,000,000
Stock split ratio			314,494.968
Total compensation expense for stock options granted					$ 11.7	$ 25.1	$ 3.7	$ 28.9	$ 4.2
Director and Executive
Class of Stock [Line Items]
Expiration period of stock options		7 years
Total compensation expense for stock options granted		$ 39.9
Director
Class of Stock [Line Items]
Stock options granted during period (shares) | shares		4,160,000
Exercise price of stock options granted during period (USD per share) | $ / shares		$ 22.00
Executive
Class of Stock [Line Items]
Stock options granted during period (shares) | shares		3,840,000
Vesting period of stock options		3 years
Stock option
Class of Stock [Line Items]
Total compensation expense for stock options granted						20.0		20.0
Profit Interest Units
Class of Stock [Line Items]
Total compensation expense for stock options granted						$ 3.4		$ 3.4
Common Stock
Class of Stock [Line Items]
Stock issued (shares) | shares				314,494,968
Subsequent Event
Class of Stock [Line Items]
Stock issued (shares) | shares	108,506,312
Gross proceeds from sale of stock	$ 2,381.0
Subsequent Event | IPO
Class of Stock [Line Items]
Stock issued (shares) | shares	90,047,612
Common stock, par value (USD per share) | $ / shares	$ 0.0001
Offering price (USD per share) | $ / shares	$ 22.00
Subsequent Event | Private Placement
Class of Stock [Line Items]
Stock issued (shares) | shares	18,458,700
Issuance price per share relative to IPO price per share (as a percent)	98.50%
Subsequent Event | Private Placement | Subsidiary of Cannae Holdings
Class of Stock [Line Items]
Gross proceeds from sale of stock	$ 200.0
Subsequent Event | Private Placement | Subsidiary of Black Knight
Class of Stock [Line Items]
Gross proceeds from sale of stock	100.0
Subsequent Event | Private Placement | Affiliate of CC Capital
Class of Stock [Line Items]
Gross proceeds from sale of stock	$ 100.0