Segment Information - Company's Segments Information (Details) - USD ($) $ in Millions	3 Months Ended										12 Months Ended
	Jan. 31, 2018	[1]	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	[2]	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Net sales:
Net sales	$ 1,334.3		$ 976.2	$ 959.7	$ 899.6	$ 1,229.6		$ 949.3	$ 931.6	$ 891.3	$ 4,169.8	$ 4,001.8	$ 4,104.9
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest											976.3	921.1	958.9
Americas [Member]
Net sales:
Net sales											1,870.9	1,841.9	1,947.0
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest											390.3	373.0	390.8
Asia-Pacific [Member]
Net sales:
Net sales											1,095.0	999.1	1,003.1
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest											286.1	256.0	264.4
Japan [Member]
Net sales:
Net sales											596.3	604.4	541.3
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest											207.3	204.6	199.9
Europe [Member]
Net sales:
Net sales											482.9	457.6	505.7
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest											86.3	81.6	97.4
Reportable Geographical Components [Member]
Net sales:
Net sales											4,045.1	3,903.0	3,997.1
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest											970.0	915.2	952.5
Other [Member]
Net sales:
Net sales											124.7	98.8	107.8
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest											$ 6.3	$ 5.9	$ 6.4

[1] For the quarter ended January 31, 2018, includes net tax expense of $146.2 million, or $1.17 per diluted share, related to the estimated impact of the 2017 Tax Act (see "Note O. Income Taxes").

[2] On a pre-tax basis, includes charges for the quarter ended January 31, 2017 of: i.$25.4 million, which reduced net earnings per diluted share by $0.13, associated with an impairment charge related to software costs capitalized in connection with the development of a new finished goods inventory management and merchandising information system (see "Note B. Summary of Significant Accounting Policies" and "Note E. Property, Plant and Equipment"); andii.$12.6 million, which reduced net earnings per diluted share by $0.06, associated with impairment charges related to financing arrangements with diamond mining and exploration companies (see "Note B. Summary of Significant Accounting Policies").