Income Tax (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 8.2	$ 14.4
(Loss) income before income taxes	(121.4)	$ (153.3)
Unrecognized tax benefits	263.9
Income Tax Contingency [Line Items]
Unrecognized tax benefits that would impact effective tax rate	249.9
Valuation Allowance of Deferred Tax Assets
Income Tax Contingency [Line Items]
Unrecognized tax benefits that would impact effective tax rate	$ 31.9