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Retirement Benefit Plans - Allocation of Plan Assets (Details) - USD ($) $ in Millions | Jan. 31, 2018 | Jan. 31, 2017 | Jan. 31, 2016
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Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | $ 121.1 | $ 107.4 | $ 101.4
Insurance contracts |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 53.0 | 46.3 |
Insurance contracts | Level 1 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 0.0 |  |
Insurance contracts | Level 2 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 53.0 |  |
Insurance contracts | Level 3 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 0.0 |  |
Other Investments |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 17.0 | 9.4 |
Other Investments | Level 1 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 0.0 |  |
Other Investments | Level 2 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 17.0 |  |
Other Investments | Level 3 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 0.0 |  |
Investments |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 70.0 | 55.7 |
Investments | Level 1 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 0.0 |  |
Investments | Level 2 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 70.0 |  |
Investments | Level 3 |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 0.0 |  |
Cash |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | 0.2 | 0.0 |
Investment Fund valued using net asset value |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Fair value of plan assets | $ 50.9 | $ 51.7 |

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- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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