Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2012	Aug. 31, 2011
Operating activities
Net earnings	$ 34,865	$ 28,341
Adjustments to reconcile net earnings to net cash provided (used) by operating activities:
Depreciation and amortization	14,987	12,854
Impairment of long-lived assets	1,570
Provision for deferred income taxes	4,679	7,678
Bad debt expense	7	29
Equity in net income of unconsolidated affiliates, net of distributions	(7,358)	(5,069)
Net loss (gain) on sale of assets	2,310	(415)
Stock-based compensation	3,193	3,201
Changes in assets and liabilities:
Receivables	38,116	27,374
Inventories	17,019	5,915
Prepaid expenses and other current assets	(145)	611
Other assets	2,847	1,273
Accounts payable and accrued expenses	(39,573)	(96,848)
Other liabilities	(1,519)	216
Net cash provided (used) by operating activities	70,998	(14,840)
Investing activities
Investment in property, plant and equipment, net	(16,705)	(6,472)
Acquisitions, net of cash acquired		(41,000)
Investments in unconsolidated affiliates		(785)
Proceeds from sale of assets	6,585	5,041
Net cash used by investing activities	(10,120)	(43,216)
Financing activities
Net proceeds from (repayments of) short-term borrowings	(223,688)	76,250
Proceeds from long-term debt, net	150,000
Principal payments on long-term debt	(442)
Proceeds from issuance of common shares	10,855	8,208
Payments to noncontrolling interest		(3,120)
Repurchase of common shares		(35,405)
Dividends paid	(8,150)	(7,169)
Net cash provided (used) by financing activities	(71,425)	38,764
Decrease in cash and cash equivalents	(10,547)	(19,292)
Cash and cash equivalents at beginning of period	41,028	56,167
Cash and cash equivalents at end of period	$ 30,481	$ 36,875