Segment Information - Company's Segments Information (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Net sales:
Net sales		$ 1,008.2	$ 1,014.6	$ 2,310.8	$ 3,066.1
Earnings (losses) from operations:
Earnings from operations for segments	[1]	234.0	169.3	320.9	615.3
Americas
Net sales:
Net sales		354.4	422.5	826.2	1,283.6
Earnings (losses) from operations:
Earnings from operations for segments	[1]	33.9	60.5	(12.0)	204.3
Asia-Pacific
Net sales:
Net sales		381.7	294.1	854.3	915.8
Earnings (losses) from operations:
Earnings from operations for segments	[1]	124.7	42.9	213.3	202.1
Japan
Net sales:
Net sales		155.7	169.3	353.1	469.3
Earnings (losses) from operations:
Earnings from operations for segments	[1]	61.9	57.4	113.6	167.0
Europe
Net sales:
Net sales		104.2	111.3	249.3	330.0
Earnings (losses) from operations:
Earnings from operations for segments	[1]	18.1	12.1	20.7	44.1
Total reportable segments
Net sales:
Net sales		996.0	997.2	2,282.9	2,998.7
Earnings (losses) from operations:
Earnings from operations for segments	[1]	238.6	172.9	335.6	617.5
Other
Net sales:
Net sales		12.2	17.4	27.9	67.4
Earnings (losses) from operations:
Earnings from operations for segments	[1]	$ (4.6)	$ (3.6)	$ (14.7)	$ (2.2)

[1] Represents earnings (loss) from operations before (i) unallocated corporate expenses, (ii) Interest expense and financing costs, (iii) Other expense (income), net and (iv) other operating expenses.