Summary Of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Aug. 31, 2013	Aug. 31, 2012	May 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Equity interest in joint venture	40.00%
Fair value of long-term debt, including current portion	$ 719,500,000		$ 723,200,000
Long-term debt, carrying amount	659,360,000		659,807,000
Maturity period for investments to be classified cash and cash equivalents, days	90 days
Goodwill resulting from acquisition	40,575,000		40,575,000
Percentage of tax benefit likely to be realized upon ultimate settlement	50.00%
Real estate acquired for development	7,100,000		7,300,000
Life insurance contracts recorded net cash	400,000		1,100,000
Insurance policy distributions	94,000,000		99,800,000
Joint venture agreement date	2011 11
Joint venture debt guaranteed percentage	50.00%
Fair value of equity	16,000,000		14,900,000
Equity income in joint venture	1,100,000	600,000
Deferred other charges	19,400,000		18,800,000
Debt issuance costs	10,600,000		11,100,000
Long-term portion of a note received in connection with the sale of our expanded shale and clay lightweight aggregates manufacturing businesses related to certain inventories - included in Deferred Other Charges	6,500,000		6,500,000
Other credits	90,000,000		91,200,000
Accumulated other comprehensive loss, adjustments related to defined benefit retirement plan and postretirement health benefit plan, net of tax	18,300,000		18,400,000
Accumulated other comprehensive loss, adjustments related to defined benefit retirement plan and postretirement health benefit plan, tax	2,400,000		2,500,000
Reclassification out of Accumulated Other Comprehensive Income
Summary Of Significant Accounting Policies [Line Items]
Cost of goods sold and Selling, general and administrative expense	100,000	700,000
Co-venturer
Summary Of Significant Accounting Policies [Line Items]
Joint venture debt guaranteed percentage	100.00%
Partner's percentage in the venture	60.00%
Real Estate
Summary Of Significant Accounting Policies [Line Items]
Gain on asset exchange	3,100,000	2,500,000
Ready-Mix Concrete
Summary Of Significant Accounting Policies [Line Items]
Goodwill resulting from acquisition	$ 40,600,000		$ 40,600,000
Riverside Defined Benefit Plans
Summary Of Significant Accounting Policies [Line Items]
Approximate number of employees and retirees of subsidiary	600
Minimum
Summary Of Significant Accounting Policies [Line Items]
Long-lived assets useful life	10 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Long-lived assets useful life	25 years
Cement Facility
Summary Of Significant Accounting Policies [Line Items]
Long-lived assets useful life	40 years
Restricted Stock Units (RSUs)
Summary Of Significant Accounting Policies [Line Items]
Award vesting period	4 years