Business and Summary of Significant Accounting Policies - New Accounting Standards (Details) - USD ($) $ in Millions		12 Months Ended
		Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015	Feb. 01, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit		$ (964.2)	$ (80.8)
Net cash provided by operating activities	[1]	169.7	414.0	$ 708.6
Net cash used in financing activities	[1]	$ 578.3	$ (343.2)	240.4
Accounting Standards Update 2016-09 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 6.9
Net cash provided by operating activities				0.5
Net cash used in financing activities				$ 0.5
Accounting Standards Update 2016-09 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member] | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					116.5
Accumulated deficit					$ 116.5

[1] During the three months ended July 31, 2016, the Company early adopted Accounting Standards Update No. 2016-09, “Improvements to Employee Share-Based Payment Accounting (Topic 718)” (“ASU 2016-09”), which addresses among other items, updates to the presentation and treatment of excess tax benefits related to stock based compensation. The Company has adopted changes to the consolidated statements of cash flows on a retrospective basis. The impact for the fiscal year ended January 31, 2015 to net cash provided by operating activities and net cash used in financing activities was $0.5 million. There was no impact to the fiscal year ended January 31, 2016.