Restructuring (benefits) charges and other facility exit costs, net (Details) - USD ($) $ in Millions		3 Months Ended
		Apr. 30, 2017	Apr. 30, 2017	Jan. 31, 2017
Restructuring Reserve [Roll Forward]
Beginning Balance		$ 7.5
Additions		0.2
Payments		(2.8)
Adjustments	[1]	(0.5)
Ending Balance		4.4
Current portion	[2]		$ 3.6	$ 5.9
Non-current portion	[2]		0.8	1.6
Total Restructuring Reserve		7.5	4.4	7.5
Lease termination and other exit costs
Restructuring Reserve [Roll Forward]
Beginning Balance		4.5
Additions		0.0
Payments		(0.7)
Adjustments	[1]	0.0
Ending Balance		3.8
Total Restructuring Reserve		4.5	3.8	4.5
Fiscal 2017 Plan | Employee termination costs
Restructuring Reserve [Roll Forward]
Beginning Balance		1.1
Additions		0.1
Payments		(1.1)
Adjustments	[1]	0.0
Ending Balance		0.1
Total Restructuring Reserve		1.1	0.1	1.1
Fiscal 2017 Plan | Lease termination and other exit costs
Restructuring Reserve [Roll Forward]
Beginning Balance		1.9
Additions		0.1
Payments		(1.0)
Adjustments	[1]	(0.5)
Ending Balance		0.5
Total Restructuring Reserve		$ 1.9	$ 0.5	$ 1.9

[1] Adjustments include the impact from the change in sublease assumptions related to certain lease terminations.

[2] The current and non-current portions of the reserve are recorded in the Condensed Consolidated Balance Sheets under “Other accrued liabilities” and “Other liabilities,” respectively.