Segments - Reconciliation of Net Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Segments
Net income	$ 27,219	$ 24,820
Interest expense	14,081	18,277
Interest income	(37)	(12)
Provision for income taxes	9,604	7,590
Depreciation expense	12,827	12,422
Amortization expense	14,270	16,853
Stock appreciation expense	792	60
Redeemable noncontrolling interests	252	662
Equity-based compensation	1,605	1,395
Severance and other permitted costs	1,947	554
Transaction costs (acquisitions and other)	100	972
Loss (gain) on disposal and impairment of assets	394	(156)
Effects of fair value adjustments to inventory		151
Adjusted EBITDA	$ 83,054	$ 83,588