Segments - Reconciliation of Net Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Segments
Net income	$ 16,625	$ 5,815	$ 24,912	$ 8,650	$ 9,919	$ 19,686	$ 18,023	$ 15,343	$ 56,002	$ 62,971	$ 48,886
Interest expense									73,677	31,395	29,360
Write-off of debt discount and deferred financing fees										74	7,103
Interest income									(66)	(177)	(152)
Provision for income taxes									14,039	20,883	22,654
Depreciation expense									46,456	24,075	25,565
Amortization expense									71,003	41,455	43,675
Stock appreciation expense									2,730	2,318	148
Redeemable noncontrolling interests									1,188	1,868	3,536
Equity-based compensation									3,906	1,695	2,534
Severance and other permitted costs									8,152	581	(157)
Transaction costs (acquisitions and other)									7,858	3,370	2,249
Gain on sale of assets									(525)	(509)	(338)
Management fee to related party											188
Effects of fair value adjustments to inventory									4,176	324	946
Change in fair value of financial instruments									6,395	6,125	382
Secondary public offering costs										1,525	1,385
Debt transaction costs									678	1,285	265
Adjusted EBITDA									$ 295,669	$ 199,258	$ 188,229