Revenue Recognition (Changes in Balances of Deferred Revenue and Wages) (Details) - POM - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Deferred Revenue
Movement in Deferred Revenue [Roll Forward]
Balance, beginning of the year	$ 183,685	$ 212,511
Amounts deferred	115,114	95,032
Amounts recognized on previous deferrals	(114,928)	(123,858)
Balance, end of the year	183,871	183,685
Deferred Wages
Movement in Deferred Revenue [Roll Forward]
Balance, beginning of the year	21,618	27,306
Amounts deferred	11,367	10,708
Amounts recognized on previous deferrals	(12,816)	(16,396)
Balance, end of the year	$ 20,169	$ 21,618