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Nominal or face amount used to calculate payments on the derivative liability.

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Derivative Instruments and Hedging Activities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Apr. 30, 2020
Derivative Instruments and Hedging Activities [Abstract]
Total debt outstanding	$ 837,743		$ 837,743		$ 775,025
Unamortized debt issuance costs	600		600
Variable rate loans outstanding	838,300		838,300
Interest Rate Swaps [Member] \| Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities [Abstract]
Notional amount of derivative liability	300,000		300,000		300,000
Interest Rate Swaps [Member] \| Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Interest Expense [Member]
Derivative Instruments and Hedging Activities [Abstract]
Net gain (losses) reclassified from Accumulated Other Comprehensive Loss	900	$ 300	1,800	$ 500
Interest Rate Swaps [Member] \| Recurring [Member] \| Level 2 [Member] \| Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities [Abstract]
Assets fair value of derivative instrument	$ 7,200		$ 7,200		$ 8,300