Unaudited Consolidated Condensed Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Feb. 28, 2013	Feb. 29, 2012
Cash flows from operating activities:
Net income	$ 21,128	$ 19,182
Adjustments to reconcile net income to net cash provided by operating activities:
Earnings from unconsolidated affiliates	(862)	(911)
Depreciation and amortization	14,454	12,913
Amortization of deferred loan costs	167	228
Foreign currency loss	917	74
Deferred income taxes	5,475	2,135
Write-down of fixed assets	73
Non-cash compensation cost	3,022	3,518
(Increase) decrease:
Receivables	6,675	7,554
Inventory	(1,675)	(2,170)
Prepaid expenses and other current assets	2,596	2,056
Increase (decrease):
Accounts payable	(3,528)	(7,150)
Other accrued liabilities	(2,796)	(229)
Income taxes	(7,430)	(4,572)
Net cash provided by operating activities	38,216	32,628
Cash flows from investing activities:
Capital expenditures	(18,803)	(15,825)
Business acquisitions, net of cash acquired	(18,589)	(19,351)
Proceeds from sale of assets	15	220
Distributions from joint venture	1,000	800
Decrease in other assets, net	55	13
Net cash used in investing activities	(36,322)	(34,143)
Cash flows from financing activities:
Borrowings under revolving credit agreement, net	2,400	13,710
Payments related to term and auto notes		(236)
Debt issuance costs		(799)
Corporate tax effect from share-based payment arrangements	3,002	1,195
Issuance of common stock from share-based payment arrangements	8,242	2,227
Payments related to withholding tax for share-based payment arrangements	(1,517)	(853)
Net cash provided by financing activities	12,127	15,244
Effect of exchange rate changes on cash	(76)	(347)
Net increase in cash and cash equivalents	13,945	13,382
Cash and cash equivalents at beginning of period	22,477	14,078
Cash and cash equivalents at end of period	$ 36,422	$ 27,460