Segments - Reconciliation of Net Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Jan. 31, 2020	Jan. 31, 2019
Segments
Net income	$ 10,879	$ 29,138	$ 24,820	$ 5,815	$ 24,912	$ 8,650	$ 64,837	$ 39,377
Interest expense	16,474			19,526			52,310	54,896
Write-off of debt discount and deferred financing fees							707
Interest income	(8)			(10)			(26)	(43)
Provision for income taxes	2,816			1,442			18,333	12,337
Depreciation expense	12,930			11,919			37,944	34,067
Amortization expense	16,492			18,301			50,271	53,262
Stock appreciation expense	(347)			442			980	1,425
Redeemable noncontrolling interests	(318)			(35)			326	778
Equity-based compensation	1,465			1,140			5,175	2,638
Severance and other permitted costs	1,700			229			3,648	5,947
Transaction costs (acquisitions and other)	434			1,066			1,733	6,660
Gain on sale of assets	(130)			(118)			(872)	(412)
Effects of fair value adjustments to inventory	310						461	4,129
Change in fair value of financial instruments								6,395
Secondary public offering costs							363
Debt transaction costs								678
Adjusted EBITDA	$ 62,697			$ 59,717			$ 236,190	$ 222,134