Revenue Recognition (Changes in Balances of Deferred Revenue and Wages) (Details) - POM - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2019	Apr. 30, 2018
Deferred Revenue
Movement in Deferred Revenue [Roll Forward]
Balance, beginning of the year	$ 218,274	$ 211,223
Amounts deferred	120,163	122,650
Amounts recognized on previous deferrals	(125,926)	(115,599)
Balance, end of the year	212,511	218,274
Deferred Wages
Movement in Deferred Revenue [Roll Forward]
Balance, beginning of the year	32,683	31,344
Amounts deferred	13,336	18,148
Amounts recognized on previous deferrals	(18,713)	(16,809)
Balance, end of the year	$ 27,306	$ 32,683

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130532-203044

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant