Segments - Reconciliation of Net Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Jan. 31, 2021	Jan. 31, 2020
Segments
Net income	$ 16,126	$ 28,469	$ 27,219	$ 10,879	$ 29,138	$ 24,820	$ 71,814	$ 64,837
Interest expense	13,454			16,474			41,060	52,310
Write-off of debt discount and deferred financing fees								707
Interest income	(6)			(8)			(57)	(26)
Provision for income taxes	5,709			2,816			23,590	18,333
Depreciation expense	11,371			12,930			36,908	37,944
Amortization expense	14,191			16,492			42,996	50,271
Stock appreciation expense	1,446			(347)			2,552	980
Redeemable noncontrolling interests	624			(318)			1,062	326
Equity-based compensation	1,877			1,465			6,734	5,175
Severance and other permitted costs	(83)			1,700			2,626	3,648
Transaction costs (acquisitions and other)	664			434			789	1,733
Gain on disposal and impairment of assets	(1,404)			(130)			(529)	(872)
Effects of fair value adjustments to inventory				310				461
Gain on legal settlement	(1,382)						(1,382)
Secondary public offering costs								363
Adjusted EBITDA	$ 62,587			$ 62,697			$ 228,163	$ 236,190