REVENUE RECOGNITION - Update to Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2018	Jan. 31, 2018
Update to Significant Accounting Policies
Amounts of unpriced change orders included in transaction prices	$ 4.3	$ 9.3
Minimum
Update to Significant Accounting Policies
Revenue recognition period	3 months
Maximum
Update to Significant Accounting Policies
Revenue recognition period	3 years
Impact of the Adoption of ASC Topic 606
Update to Significant Accounting Policies
Impact on revenues, changes in estimates of the costs-to-complete active contracts	$ 4.6
Accounts payable
Update to Significant Accounting Policies
Amounts retained from vendors and subcontractors by the Company	$ 39.5	$ 38.7