Business and Summary of Significant Accounting Policies - New Accounting Standards (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Feb. 01, 2018	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue		$ 737.3	$ 660.9	$ 611.7	$ 559.9	$ 553.8	$ 515.3	$ 501.8	$ 485.7		$ 2,569.8	$ 2,056.6	$ 2,031.0
Capitalized contract cost		93.0									93.0
Accumulated deficit adjustment		(2,147.4)				(2,084.9)					(2,147.4)	(2,084.9)
Scenario, Forecast | Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expected impact of new accounting pronouncement										$ 1.3
Accumulated deficit | Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative increase to accumulated deficit						$ (1.9)						$ (1.9)
Impact from the adoption of ASC 606 and 340-40 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue	$ 89.0
Capitalized contract cost	90.4
Accumulated deficit adjustment	$ 179.4	$ (189.5)									$ (189.5)