Segment Information Sales to Unaffiliated Customers and Long-Lived Assets by Geographic Areas (Details) - USD ($) $ in Millions	3 Months Ended										12 Months Ended
	Jan. 31, 2018		Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017		Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 1,334.3	[1]	$ 976.2	$ 959.7	$ 899.6	$ 1,229.6	[2]	$ 949.3	$ 931.6	$ 891.3	$ 4,169.8	$ 4,001.8	$ 4,104.9
Long-Lived Assets	1,047.3					982.0					1,047.3	982.0	984.2
UNITED STATES [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales											1,739.0	1,691.4	1,795.5
Long-Lived Assets	724.5					691.3					724.5	691.3	706.9
Japan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales											596.3	604.4	541.3
Long-Lived Assets	21.4					21.7					21.4	21.7	20.6
Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales											1,834.5	1,706.0	1,768.1
Long-Lived Assets	$ 301.4					$ 269.0					$ 301.4	$ 269.0	$ 256.7

[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").