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COMMITMENTS - General Information (Details) $ in Millions | 12 Months Ended
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Jan. 31, 2018 USD ($) item | Jan. 31, 2017 USD ($) | Jan. 31, 2016 USD ($)
Commitments |  |  |
The number of option terms remaining | item | 1 |  |
The period of the option terms | 2 years |  |
Costs of Revenues |  |  |
Commitments |  |  |
Rent incurred on construction projects included in the costs of revenues | $ 20.3 | $ 13.2 | $ 15.0
Selling, General and Administrative Expenses |  |  |
Commitments |  |  |
Rent expense included in selling, general and administrative expenses of continuing operations | 0.7 | $ 0.6 | $ 0.3
TRC |  |  |
Commitments |  |  |
Annual lease amount for primary offices and plant | 0.3 |  |
APC |  |  |
Commitments |  |  |
Annual lease amount for primary offices and plant | $ 0.1 |  |

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- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717 + Details
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