Segments - Reconciliation of Net Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2017	Jul. 31, 2016
Segments
Adjusted EBITDA	$ 52,752	$ 45,941
Interest expense	(7,500)	(7,577)
Write-off of debt discount and deferred financing fees	(74)	(5,426)
Interest income	(23)	(43)
Income tax expense	(10,060)	(6,159)
Depreciation expense	(5,990)	(6,382)
Amortization expense	(10,355)	(9,413)
Stock appreciation (expense) or income	(590)	92
Redeemable noncontrolling interests	(866)	(292)
Equity-based compensation	(473)	(673)
Severance and other permitted costs	(205)	(140)
Transaction costs (acquisitions and other)	(159)	(654)
Gain on sale of assets	390	198
Management fee to related party		(188)
Effects of fair value adjustments to inventory		(164)
Interest rate cap mark-to-market	(196)	(43)
Secondary public offering costs	(631)
Debt transaction costs	(723)
Net income	$ 15,343	$ 9,163