CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (23.7)	$ (119.8)	$ (145.5)	$ (393.4)
Other comprehensive (loss) income, net of reclassifications:
Net gain (loss) on derivative instruments (net of tax effect of ($1.1), $0.3, ($2.9), and $1.7, respectively)	11.5	(2.4)	29.1	(15.4)
Change in net unrealized gain on available-for-sale debt securities (net of tax effect of ($0.1), ($0.4), ($0.1) and ($0.3), respectively)	2.4	0.2	1.7	0.4
Change in defined benefit pension items (net of tax effect of ($1.3), $0.0, ($2.8) and $0.0, respectively)	1.6	0.2	11.6	0.0
Net change in cumulative foreign currency translation (loss) gain (net of tax effect of $0.0, $0.0, $0.5 and ($0.9), respectively)	(22.1)	(0.6)	(76.1)	38.0
Total other comprehensive (loss) income	(6.6)	(2.6)	(33.7)	23.0
Total comprehensive loss	$ (30.3)	$ (122.4)	$ (179.2)	$ (370.4)