Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Current tax expense (benefit):
Federal	$ 22,182	$ 10,326	$ (7,057)
State	6,210	3,853	1,769
Current income tax expense (benefit)	28,392	14,179	(5,288)
Deferred tax expense (benefit)	49,810	45,337	(98,178)
Total income tax expense (benefit)	$ 78,202	$ 59,516	$ (103,466)