Segment Information - Supplemental Geographic and Customer Solution Set Information (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended								12 Months Ended
	Feb. 07, 2019		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenue	$ 178.7	[1]	$ 480.1	$ 442.1	$ 420.6	$ 395.3	$ 432.7	$ 408.2	$ 398.9	$ 174.1	$ 1,738.1	$ 1,413.9	[1]	$ 1,716.4
Finance & Risk
Segment Reporting Information [Line Items]
Revenue	104.6										1,043.9	836.6		1,026.2
Sales & Marketing
Segment Reporting Information [Line Items]
Revenue	74.1										694.2	577.3		690.2
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenue	148.2										1,459.9	1,316.5		1,420.6
Operating Segments | North America | Finance & Risk
Segment Reporting Information [Line Items]
Revenue	80.4										811.1	728.2		792.6
Operating Segments | North America | Sales & Marketing
Segment Reporting Information [Line Items]
Revenue	67.8										648.8	588.3		628.0
Operating Segments | International
Segment Reporting Information [Line Items]
Revenue	56.4										299.3	236.3		295.8
Operating Segments | International | Finance & Risk
Segment Reporting Information [Line Items]
Revenue	43.4										243.6	191.3		233.6
Operating Segments | International | Sales & Marketing
Segment Reporting Information [Line Items]
Revenue	13.0										55.7	45.0		62.2
Corporate and other
Segment Reporting Information [Line Items]
Revenue	(25.9)										(21.1)	(138.9)		0.0
Corporate and other | Finance & Risk
Segment Reporting Information [Line Items]
Revenue	(19.2)										(10.8)	(82.9)		0.0
Corporate and other | Sales & Marketing
Segment Reporting Information [Line Items]
Revenue	$ (6.7)										$ (10.3)	$ (56.0)		$ 0.0

[1] See Note 1 "Basis of Presentation" for further discussion.