Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2017	Jan. 31, 2016
Statement of Cash Flows [Abstract]
Payments to Acquire Other Investments	$ 57,250	$ 34,250
OPERATING ACTIVITIES
Net income	53,851	45,351
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,719	11,804
Net loss on disposal of property, plant and equipment	286	113
Stock-based compensation expense	2,477	2,651
Deferred income taxes	10,173	9,319
Pension contributions in excess of expense	(27,706)	(4,803)
Tax benefit from stock-based compensation	0	(4,760)
Contributions of employer stock to employee benefit plan	2,926	1,761
Other non-cash items	(429)	(995)
Changes in operating assets and liabilities:
Customer receivables	(3,767)	(3,261)
Inventories	(2,571)	(2,635)
Prepaid expenses and other assets	(1,983)	(5,613)
Accounts payable	(2,110)	(133)
Accrued compensation and related expenses	2,598	3,800
Income taxes payable	0	(1,791)
Other accrued expenses	4,200	2,753
Net Cash Provided by Operating Activities	51,664	53,561
INVESTING ACTIVITIES
Payments to acquire property, plant and equipment	(13,654)	(25,167)
Proceeds from sales of property, plant and equipment	37	96
Proceeds from Maturities, Prepayments and Calls of Other Investments	23,000	29,250
Investment in promotional displays	(3,867)	(3,608)
Net Cash Used by Investing Activities	(51,734)	(33,679)
FINANCING ACTIVITIES
Payments of long-term debt	(1,290)	(1,139)
Proceeds from long-term debt	2,687	2,805
Proceeds from issuance of common stock	2,359	7,727
Repurchase of common stock	(13,407)	(11,996)
Notes receivable, net	208	(4,263)
Payments Related to Tax Withholding for Share-based Compensation	(1,734)	(2,638)
Tax benefit from stock-based compensation	0	4,760
Net Cash Used by Financing Activities	(11,177)	(4,744)
Net (Decrease) Increase in Cash and Cash Equivalents	(11,247)	15,138
Cash and Cash Equivalents, Beginning of Period	174,463	149,541
Cash and Cash Equivalents, End of Period	$ 163,216	$ 164,679