Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 249	$ 259	$ 148
Additions (Reductions) Charged to Cost and Expenses	323	72	169
Other	0	0	78
Deductions	(100)	(82)	(136)
Balance at End of Year	472	249	259
Reserve for Cash Discounts [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	1,451	1,627	979
Additions (Reductions) Charged to Cost and Expenses	16,810	16,994	11,999
Other	0	0	584
Deductions	(17,090)	(17,170)	(11,935)
Balance at End of Year	1,171	1,451	1,627
Reserve for Sales Returns and Allowances [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	4,545	4,381	2,131
Additions (Reductions) Charged to Cost and Expenses	17,049	11,867	11,318
Other	0	0	1,829
Deductions	(17,053)	(11,703)	(10,897)
Balance at End of Year	$ 4,541	$ 4,545	$ 4,381