Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2013	Nov. 30, 2012
Operating activities
Net earnings	$ 28,340	$ 32,622	$ 84,693	$ 67,487
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	20,095	16,101	39,555	31,088
Impairment of long-lived assets	30,734	(50)	35,375	1,520
Provision for deferred income taxes	(13,110)	(1,320)	(21,534)	3,359
Bad debt expense (income)	185	492	(296)	499
Equity in net income of unconsolidated affiliates, net of distributions	(3,506)	(7,057)	(9,421)	(14,415)
Net gain on sale of assets	(7,188)	(2,379)	(11,850)	(69)
Stock-based compensation	4,722	3,740	8,502	6,933
Excess tax benefits - stock-based compensation	(1,534)		(5,832)
Gain on previously held interest in TWB			(11,000)
Changes in assets and liabilities, net of impact of acquisitions:
Receivables	7,574	30,634	15,229	68,750
Inventories	(21,838)	40,883	(21,323)	57,901
Prepaid expenses and other current assets	4,072	1,746	1,707	1,602
Other assets	139	91	575	2,937
Accounts payable and accrued expenses	(23,922)	(30,617)	16,700	(70,191)
Other liabilities	4,556	3,495	2,703	1,978
Net cash provided by operating activities	29,319	88,381	123,783	159,379
Investing activities
Investment in property, plant and equipment	(17,060)	(7,911)	(30,414)	(24,616)
Acquisitions, net of cash acquired	276	(62,110)	53,233	(62,110)
Distributions from unconsolidated affiliates	3,668		9,223
Proceeds from sale of assets	16,086	9,090	23,733	15,675
Net cash provided (used) by investing activities	2,970	(60,931)	55,775	(71,051)
Financing activities
Net payments of short-term borrowings	(18,736)	(14,508)	(70,277)	(238,196)
Proceeds from long-term debt				150,000
Principal payments on long-term debt	(285)	(363)	(569)	(805)
Proceeds from issuance of common shares	4,286	4,773	6,487	15,628
Excess tax benefits - stock-based compensation	1,534		5,832
Payments to noncontrolling interest	(875)	(5,990)	(2,638)	(5,990)
Repurchase of common shares	(19,800)		(50,316)
Dividends paid	(10,407)	(8,954)	(10,407)	(17,104)
Net cash used by financing activities	(44,283)	(25,042)	(121,888)	(96,467)
Increase (decrease) in cash and cash equivalents	(11,994)	2,408	57,670	(8,139)
Cash and cash equivalents at beginning of period	121,049	30,481	51,385	41,028
Cash and cash equivalents at end of period	$ 109,055	$ 32,889	$ 109,055	$ 32,889