Commitments	12 Months Ended
May 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Commitments	Commitments Operating Leases. We lease certain mobile and other equipment, office space and other items which in the normal course of business may be renewed or replaced by subsequent leases. Total expense for such operating leases (other than for mineral rights) was $15.6 million in 2013, $14.5 million in 2012 and $15.5 million in 2011. Total future payments under non-cancelable operating leases with an initial or remaining term of more than one year were $44.6 million at May 31, 2013. Estimated lease payments for each of the five succeeding years are $9.7 million, $8.1 million, $5.6 million,$5.7 million and $5.1 million. Purchase Obligations. We purchase coal for use in our operations under long-term supply contracts that, in certain cases, require minimum transportation charges. In addition, we purchase mining services at our north Texas cement plant under a long-term contract that contains provisions for minimum payments. We expect to utilize these required amounts of material and services in the normal course of business operations. Total cost incurred under contracts requiring minimum purchases or payments was $6.9 million in 2013, $16.1 million in 2012 and $27.0 million in 2011. Total future minimum payments under the contracts were $26.9 million at May 31, 2013. Estimated minimum payments for each of the five succeeding years are $6.3 million, $6.3 million, $6.3 million, $6.3 million and $1.7 million. We entered into a long-term contract with a power supplier during the construction of our Oro Grande, California cement plant which included the construction of certain power facilities at the plant. We recognized a capital lease obligation of $2.4 million related to payment obligations under the power supply contract related to these facilities. The total future commitment under the contract, including maintenance services to be provided by the power supplier, related to these facilities was $5.3 million at May 31, 2013. Payments for each of the five succeeding years are $0.4 million per year.

Commitments

12 Months Ended

May 31, 2013

Commitments and Contingencies Disclosure [Abstract]

Operating Leases. We lease certain mobile and other equipment, office space and other items which in the normal course of business may be renewed or replaced by subsequent leases. Total expense for such operating leases (other than for mineral rights) was $15.6 million in 2013, $14.5 million in 2012 and $15.5 million in 2011. Total future payments under non-cancelable operating leases with an initial or remaining term of more than one year were $44.6 million at May 31, 2013. Estimated lease payments for each of the five succeeding years are $9.7 million, $8.1 million, $5.6 million,$5.7 million and $5.1 million.

Purchase Obligations. We purchase coal for use in our operations under long-term supply contracts that, in certain cases, require minimum transportation charges. In addition, we purchase mining services at our north Texas cement plant under a long-term contract that contains provisions for minimum payments. We expect to utilize these required amounts of material and services in the normal course of business operations. Total cost incurred under contracts requiring minimum purchases or payments was $6.9 million in 2013, $16.1 million in 2012 and $27.0 million in 2011. Total future minimum payments under the contracts were $26.9 million at May 31, 2013. Estimated minimum payments for each of the five succeeding years are $6.3 million, $6.3 million, $6.3 million, $6.3 million and $1.7 million.

We entered into a long-term contract with a power supplier during the construction of our Oro Grande, California cement plant which included the construction of certain power facilities at the plant. We recognized a capital lease obligation of $2.4 million related to payment obligations under the power supply contract related to these facilities. The total future commitment under the contract, including maintenance services to be provided by the power supplier, related to these facilities was $5.3 million at May 31, 2013. Payments for each of the five succeeding years are $0.4 million per year.