Schedule II - Valuation And Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2014		Apr. 30, 2013		Apr. 30, 2012
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 148	[1]	$ 93	[1]	$ 67	[1]
Additions (Reductions) Charged to Cost and Expenses	31	[1]	92	[1]	123	[1]
Other		[1]		[1]		[1]
Deductions	(77)	[1],[2]	(37)	[1],[2]	(97)	[1],[2]
Balance at End of Year	102	[1]	148	[1]	93	[1]
Reserve for Cash Discounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	669	[1]	645	[1]	710	[1]
Additions (Reductions) Charged to Cost and Expenses	8,529	[1],[3]	8,174	[1],[3]	7,317	[1],[3]
Other		[1]		[1]		[1]
Deductions	(8,471)	[1],[4]	(8,150)	[1],[4]	(7,382)	[1],[4]
Balance at End of Year	727	[1]	669	[1]	645	[1]
Reserve for Sales Returns and Allowances [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	1,536	[1]	1,301	[1]	1,194	[1]
Additions (Reductions) Charged to Cost and Expenses	7,245	[1],[3]	7,496	[1],[3]	7,040	[1],[3]
Other		[1]		[1]		[1]
Deductions	(7,142)	[1]	(7,261)	[1]	(6,933)	[1]
Balance at End of Year	$ 1,639	[1]	$ 1,536	[1]	$ 1,301	[1]

[1] All reserves relate to accounts receivable.

[2] Principally write-offs, net of collections.

[3] Reduction of gross sales.

[4] Cash discounts granted.