Segment Information - Company's Segments Information (Details) - USD ($) $ in Millions	3 Months Ended											12 Months Ended
	Jan. 31, 2017	[1]	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	[2]	Oct. 31, 2015	Jul. 31, 2015	[3]	Apr. 30, 2015	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Net sales:
Net sales	$ 1,229.6		$ 949.3	$ 931.6	$ 891.3	$ 1,213.6		$ 938.2	$ 990.5		$ 962.4	$ 4,001.8	$ 4,104.9	$ 4,249.9
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest												921.1	958.9	1,028.5
Americas [Member]
Net sales:
Net sales												1,841.9	1,947.0	2,033.5
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest												373.0	390.8	435.5
Asia-Pacific [Member]
Net sales:
Net sales												999.1	1,003.1	1,025.2
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest												256.0	264.4	281.6
Japan [Member]
Net sales:
Net sales												604.4	541.3	554.3
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest												204.6	199.9	196.0
Europe [Member]
Net sales:
Net sales												457.6	505.7	513.3
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest												81.6	97.4	110.5
Reportable Geographical Components [Member]
Net sales:
Net sales												3,903.0	3,997.1	4,126.3
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest												915.2	952.5	1,023.6
Other [Member]
Net sales:
Net sales												98.8	107.8	123.6
Earnings (losses) from operations:
Segment Reporting Earnings Losses From Continuing Operations Before Unallocated Corporate Expenses Interest												$ 5.9	$ 6.4	$ 4.9

[1] 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" and "Note J. Commitments and Contingencies").

[2] On a pre-tax basis, includes charges for the quarter ended January 31, 2016 of: i.$28.3 million, which reduced net earnings per diluted share by $0.14, associated with an impairment charge related to a financing arrangement with Koidu Limited (see "Note B. Summary of Significant Accounting Policies" and "Note J. Commitments and Contingencies"); andii.$8.8 million, which reduced net earnings per diluted share by $0.04, associated with severance related to staffing reductions and subleasing of certain office space for which only a portion of the Company's future rent obligations will be recovered (see "Note J. Commitments and Contingencies").

[3] On a pre-tax basis, includes a charge of $9.6 million for the quarter ended July 31, 2015, which reduced net earnings per diluted share by $0.05, associated with an impairment charge related to a financing arrangement with Koidu Limited (see "Note B. Summary of Significant Accounting Policies" and "Note J. Commitments and Contingencies").