Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2016	Jul. 31, 2015
Statement of Cash Flows [Abstract]
Payments to Acquire Other Investments	$ 42,500	$ 8,000
OPERATING ACTIVITIES
Net income	21,661	15,158
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,497	3,558
Net loss on disposal of property, plant and equipment	136	9
Stock-based compensation expense	846	963
Deferred income taxes	1,896	1,388
Pension contributions in excess of expense	(1,159)	(723)
Tax benefit from stock-based compensation	0	(2,297)
Contributions of employer stock to employee benefit plan	2,926	1,761
Other non-cash items	(152)	(273)
Changes in operating assets and liabilities:
Customer receivables	(1,907)	(7,141)
Inventories	(720)	(1,043)
Prepaid expenses and other assets	617	428
Accounts payable	3,910	543
Accrued compensation and related expenses	(7,264)	(2,948)
Income taxes payable	7,198	5,701
Other accrued expenses	462	2,571
Net Cash Provided by Operating Activities	32,947	17,655
INVESTING ACTIVITIES
Payments to acquire property, plant and equipment	(4,227)	(11,133)
Proceeds from sales of property, plant and equipment	9	82
Proceeds from Maturities, Prepayments and Calls of Other Investments	7,500	5,750
Investment in promotional displays	(1,353)	(1,994)
Net Cash Used by Investing Activities	(40,571)	(15,295)
FINANCING ACTIVITIES
Payments of long-term debt	(426)	(370)
Proceeds from long-term debt	750	0
Proceeds from issuance of common stock	2,020	3,556
Repurchase of common stock	(5,100)	(1,768)
Notes receivable, net	167	42
Payments Related to Tax Withholding for Share-based Compensation	(1,687)	(2,638)
Tax benefit from stock-based compensation	0	2,297
Net Cash (Used) Provided by Financing Activities	(4,276)	1,119
Net (Decrease) Increase in Cash and Cash Equivalents	(11,900)	3,479
Cash and Cash Equivalents, Beginning of Period	174,463	149,541
Cash and Cash Equivalents, End of Period	$ 162,563	$ 153,020