CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 66.7	$ (23.7)	$ 82.7	$ (145.5)
Other comprehensive income (loss), net of reclassifications:
Net (loss) gain on derivative instruments (net of tax effect of $0.4, ($1.1), ($1.6) and ($2.9), respectively)	(3.3)		(4.3)
Net (loss) gain on derivative instruments (net of tax effect of $0.4, ($1.1), ($1.6) and ($2.9), respectively)		11.5		29.1
Change in net unrealized gain on available-for-sale debt securities (net of tax effect of ($0.1), ($0.1), ($0.4) and ($0.1), respectively)	0.5	2.4	1.4	1.7
Change in defined benefit pension items (net of tax effect of $0.3, ($1.3), $0.8 and ($2.8), respectively)	(0.1)	1.6	(2.5)	11.6
Net change in cumulative foreign currency translation gain (loss) (net of tax effect of $0.1, $0.0, $0.1 and $0.5, respectively)	17.3	(22.1)	(15.9)	(76.1)
Total other comprehensive income (loss)	14.4	(6.6)	(21.3)	(33.7)
Total comprehensive income (loss)	$ 81.1	$ (30.3)	$ 61.4	$ (179.2)