Summary of Operating Results and Certain Other Financial Data for Business Segments (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2010
Segment Reporting Information [Line Items]
Net sales	$ 647,003	$ 621,813	$ 621,064
Segment operating profit (loss)			31,454
Corporate	(35,771)	(30,843)	(41,205)
Identifiable assets	1,576,928	1,551,011	1,531,747
Interest	(34,835)	(47,583)	(52,240)
Depreciation, depletion and amortization	60,952	64,297	63,925
Loss on debt retirements		(29,619)
Capital expenditures	106,336	45,683	13,659
INCOME (LOSS) BEFORE INCOME TAXES	8,472	(106,807)	(61,991)
Cement Segment
Segment Reporting Information [Line Items]
Sales to external customers	268,886	240,449	249,366
Intersegment sales	46,407	46,845	45,147
Segment operating profit (loss)	20,488	(10,249)	13,996
Identifiable assets	1,135,336	1,082,524	1,093,301
Depreciation, depletion and amortization	35,078	36,576	35,828
Capital expenditures	78,618	30,413	7,672
Aggregates
Segment Reporting Information [Line Items]
Sales to external customers	149,110	147,862	143,045
Intersegment sales	25,450	24,563	21,902
Segment operating profit (loss)	33,555	22,638	13,801
Identifiable assets	219,074	201,917	229,084
Depreciation, depletion and amortization	15,745	18,963	19,873
Capital expenditures	21,332	6,124	5,293
Consumer Products
Segment Reporting Information [Line Items]
Sales to external customers	229,007	233,502	228,653
Intersegment sales	2,721	2,646	2,730
Segment operating profit (loss)	25,035	(11,151)	3,657
Identifiable assets	90,717	106,643	85,641
Depreciation, depletion and amortization	8,981	7,625	7,065
Capital expenditures	4,569	8,229	564
Intersegment Elimination
Segment Reporting Information [Line Items]
Net sales	(74,578)	(74,054)	(69,779)
Corporate
Segment Reporting Information [Line Items]
Identifiable assets	131,801	159,927	123,721
Depreciation, depletion and amortization	1,148	1,133	1,159
Capital expenditures	1,817	917	130
Cement
Segment Reporting Information [Line Items]
Net sales	232,007	209,586	221,068
Stone, Sand And Gravel
Segment Reporting Information [Line Items]
Net sales	64,393	68,645	69,081
Ready-Mix Concrete
Segment Reporting Information [Line Items]
Net sales	182,418	180,733	175,581
Other products
Segment Reporting Information [Line Items]
Net sales	89,529	94,892	95,928
Delivery Fees
Segment Reporting Information [Line Items]
Net sales	$ 78,656	$ 67,957	$ 59,406