Retirement Benefit Plans - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Retirement Benefits [Abstract]
Funded percentage	77.00%
Accumulated benefit obligation	$ 139.5	$ 128.2
Actual plan asset allocations	44.00%	43.00%
Estimated future employer contributions in next fiscal year	$ 4.7
Expected long-term rate of return on plan assets	3.30%	4.30%	3.80%
Domestic Plan
Defined Contribution Plan Disclosure [Line Items]
Maximum annual contributions per employee	75.00%
Cost Recognized	$ 17.3	$ 16.4	$ 17.3
Foreign Plan
Defined Contribution Plan Disclosure [Line Items]
Contributions paid by employer	$ 27.2	$ 26.6	$ 23.0

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Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
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Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Percentage of plan assets to benefit obligation of defined benefit plan.

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Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

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Amount of cost for defined contribution plan.

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Amount of discretionary contributions made by an employer to a defined contribution plan.

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Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

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