Revenue Recognition (Deferred Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Apr. 30, 2019	Apr. 30, 2018
Disaggregation of Revenue [Line Items]
Document Period End Date	Jul. 31, 2019
POM
Disaggregation of Revenue [Line Items]
Contract with Customer, Liability, Current	$ 110,700
Movement in Deferred Revenue [Roll Forward]
Balance, end of the period	176,000
POM | Deferred Revenue
Movement in Deferred Revenue [Roll Forward]
Balance, beginning of the period	212,511	$ 218,274
Amounts deferred	1,723	1,392
Amounts recognized on previous deferrals	(38,212)	(40,857)
Balance, end of the period	176,022	178,809
POM | Deferred Wages
Movement in Deferred Revenue [Roll Forward]
Balance, beginning of the period	27,306	32,683
Amounts deferred	23	62
Amounts recognized on previous deferrals	(5,324)	(5,917)
Balance, end of the period	22,005	26,828
Tax Identity Shield®
Disaggregation of Revenue [Line Items]
Contract with Customer, Liability, Current	$ 25,400	$ 31,900	$ 29,700	$ 36,400