Segment Information - Supplemental Geographic and Customer Solution Set Information (Details) - USD ($) $ in Millions	3 Months Ended						6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020		Jun. 30, 2020	Sep. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenue	$ 504.5	$ 479.9	$ 444.4	$ 418.7	$ 395.7	[1]	$ 814.4	$ 1,258.8	$ 1,738.7
Finance & Risk
Segment Reporting Information [Line Items]
Revenue	295.6				241.6
Sales & Marketing
Segment Reporting Information [Line Items]
Revenue	208.9				154.1
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenue	339.4				341.5
Operating Segments | North America | Finance & Risk
Segment Reporting Information [Line Items]
Revenue	190.5				192.8
Operating Segments | North America | Sales & Marketing
Segment Reporting Information [Line Items]
Revenue	148.9				148.7
Operating Segments | International
Segment Reporting Information [Line Items]
Revenue	169.9				71.6
Operating Segments | International | Finance & Risk
Segment Reporting Information [Line Items]
Revenue	107.4				58.6
Operating Segments | International | Sales & Marketing
Segment Reporting Information [Line Items]
Revenue	62.5				13.0
Corporate and other
Segment Reporting Information [Line Items]
Revenue	(4.8)				(17.4)
Corporate and other | Finance & Risk
Segment Reporting Information [Line Items]
Revenue	(2.3)				(9.8)
Corporate and other | Sales & Marketing
Segment Reporting Information [Line Items]
Revenue	$ (2.5)				$ (7.6)

[1] See discussion in Note 1 - Basis of Presentation for further detail regarding the elimination of the International lag reporting.