Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
Statement of Cash Flows [Abstract]
Payments to Acquire Other Investments	$ 50,500	$ 19,750
OPERATING ACTIVITIES
Net income	39,298	33,338
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,873	7,513
Net loss on disposal of property, plant and equipment	174	82
Stock-based compensation expense	1,649	1,795
Deferred income taxes	11,250	3,813
Pension contributions in excess of expense	(10,732)	(1,677)
Tax benefit from stock-based compensation	0	(3,599)
Contributions of employer stock to employee benefit plan	2,926	1,761
Other non-cash items	88	(169)
Changes in operating assets and liabilities:
Customer receivables	(12,847)	(15,296)
Inventories	(1,942)	(2,317)
Prepaid expenses and other assets	(2,917)	(831)
Accounts payable	2,878	5,569
Accrued compensation and related expenses	(1,754)	4,743
Income taxes payable	0	(246)
Other accrued expenses	3,202	7,509
Net Cash Provided by Operating Activities	40,146	41,988
INVESTING ACTIVITIES
Payments to acquire property, plant and equipment	(10,354)	(21,131)
Proceeds from sales of property, plant and equipment	26	81
Proceeds from Maturities, Prepayments and Calls of Other Investments	12,500	18,250
Investment in promotional displays	(2,089)	(3,245)
Net Cash Used by Investing Activities	(50,417)	(25,795)
FINANCING ACTIVITIES
Payments of long-term debt	(854)	(752)
Proceeds from long-term debt	2,003	0
Proceeds from issuance of common stock	2,241	5,987
Repurchase of common stock	(10,443)	(7,000)
Notes receivable, net	208	42
Payments Related to Tax Withholding for Share-based Compensation	(1,703)	(2,638)
Tax benefit from stock-based compensation	0	3,599
Net Cash Used by Financing Activities	(8,548)	(762)
Net (Decrease) Increase in Cash and Cash Equivalents	(18,819)	15,431
Cash and Cash Equivalents, Beginning of Period	174,463	149,541
Cash and Cash Equivalents, End of Period	$ 155,644	$ 164,972