Asset Employed for Continuing Operations for Corporations Reportable Business Segments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Segment Reporting Asset Reconciling Item [Line Items]
Assets employed, Total	$ 7,438,448	$ 7,464,392	$ 7,338,858
Operating Segments
Segment Reporting Asset Reconciling Item [Line Items]
Assets employed, Total	4,603,748	4,339,277	3,815,359
Operating Segments | Mid-America Group
Segment Reporting Asset Reconciling Item [Line Items]
Assets employed, Total	1,347,706	1,290,833	1,313,472
Operating Segments | Southeast Group
Segment Reporting Asset Reconciling Item [Line Items]
Assets employed, Total	597,018	604,044	604,261
Operating Segments | West Group
Segment Reporting Asset Reconciling Item [Line Items]
Assets employed, Total	2,659,024	2,444,400	1,897,626
Operating Segments | Cement
Segment Reporting Asset Reconciling Item [Line Items]
Assets employed, Total	1,973,686	2,451,799	3,038,802
Operating Segments | Magnesia Specialties
Segment Reporting Asset Reconciling Item [Line Items]
Assets employed, Total	147,217	150,359	150,068
Corporate
Segment Reporting Asset Reconciling Item [Line Items]
Assets employed, Total	$ 713,797	$ 522,957	$ 334,629