Business Segments - Summary of Operating Results and Certain Other Financial Data for Business Segments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Segment Reporting Information [Line Items]
NET SALES	$ 697,081	$ 594,105	$ 571,906
Segment operating profit (loss)	48,373	70,893	(5,304)
Corporate	(39,826)	(35,771)	(30,843)
Interest	(32,807)	(34,835)	(47,583)
Loss on debt retirements	0	0	(29,619)
INCOME (LOSS) BEFORE INCOME TAXES FROM CONTINUING OPERATIONS	(24,260)	287	(113,349)
Identifiable assets	1,635,825	1,576,928	1,551,011
Depreciation, depletion and amortization	59,865	60,952	64,297
Capital expenditures	92,518	105,983	44,637
Cement Segment
Segment Reporting Information [Line Items]
Sales to external customers	336,614	268,886	240,449
Intersegment sales	44,890	46,407	46,845
Segment operating profit (loss)	44,062	20,488	(10,249)
Identifiable assets	1,174,879	1,135,336	1,082,524
Capital expenditures	77,793	78,618	30,413
Aggregates
Segment Reporting Information [Line Items]
Sales to external customers	128,901	96,212	97,955
Intersegment sales	26,705	21,145	20,399
Segment operating profit (loss)	14,443	25,370	16,096
Identifiable assets	168,255	219,074	201,917
Capital expenditures	4,298	20,979	5,078
Consumer Products
Segment Reporting Information [Line Items]
Sales to external customers	231,566	229,007	233,502
Intersegment sales	162	2,721	2,646
Segment operating profit (loss)	(10,132)	25,035	(11,151)
Identifiable assets	182,839	90,717	106,643
Capital expenditures	8,820	4,569	8,229
Intersegment Elimination
Segment Reporting Information [Line Items]
NET SALES	(71,757)	(70,273)	(69,890)
Corporate
Segment Reporting Information [Line Items]
Identifiable assets	109,852	131,801	159,927
Capital expenditures	1,607	1,817	917
Cement
Segment Reporting Information [Line Items]
NET SALES	301,106	232,007	209,586
Stone, Sand And Gravel
Segment Reporting Information [Line Items]
NET SALES	83,333	64,393	68,645
Ready-Mix Concrete
Segment Reporting Information [Line Items]
NET SALES	231,195	182,418	180,733
Other products
Segment Reporting Information [Line Items]
NET SALES	10,758	50,409	56,272
Delivery Fees
Segment Reporting Information [Line Items]
NET SALES	70,689	64,878	56,670
Continuing operations
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	58,613	59,438	62,433
Continuing operations | Cement Segment
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	35,219	35,078	36,576
Continuing operations | Aggregates
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	13,053	14,231	17,099
Continuing operations | Consumer Products
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	9,353	8,981	7,625
Continuing operations | Corporate
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	$ 988	$ 1,148	$ 1,133