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REVENUE RECOGNITION - Performance Obligations (Details)
$ in Millions
Apr. 30, 2019
USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-05-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Unearned revenue $ 2.9
Unearned revenue, timing of satisfaction 12 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-05-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Unearned revenue $ 0.1
Unearned revenue, timing of satisfaction