Revenue Recognition, Contracts with Customers, Accounts Receivable, net and Contract Liability (Deferred Revenue) Balances (Details) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Jan. 31, 2019		Apr. 30, 2018
Balances from contracts with customers [Abstract]
Accounts receivable, net		$ 194,764	[1]	$ 212,377
Contract liability (Deferred revenue)		271,541	[1]	486,353
Contract liability (Deferred revenue) (included in Other Long-Term Liabilities)		14,722
Increase/(decrease) [Abstract]
Sales return reserve recorded in contract liability		36,700
Revenue recognized from beginning contract liability		131,400		518,200
Balances without Adoption of Topic 606 [Member] | ASU 2014-09 [Member]
Balances from contracts with customers [Abstract]
Accounts receivable, net	[1],[2]			212,377
Contract liability (Deferred revenue)	[1],[2]			486,353
Contract liability (Deferred revenue) (included in Other Long-Term Liabilities)	[2]			0
Effect of Change Higher/(Lower) [Member] | ASU 2014-09 [Member]
Balances from contracts with customers [Abstract]
Accounts receivable, net				93,349
Contract liability (Deferred revenue)				$ 89,364
Increase/(decrease) [Abstract]
Accounts receivable, net	[1]	(17,613)
Contract liability (Deferred revenue)	[1]	(214,812)
Contract liability (Deferred revenue) (included in Other Long-Term Liabilities)		$ 14,722

[1] Due to the adoption of the new revenue standard, the sales return reserve as of January 31, 2019 of $36.7 million is recorded in Contract Liability (Deferred Revenue). In prior periods, it was recorded as a reduction to Accounts Receivable, net on the Unaudited Condensed Consolidated Statement of Financial Position.

[2] As noted above, prior period amounts have not been adjusted under the modified retrospective method.