Summary of Asset Used in Each of Business Segments (Detail) (USD $) In Thousands, unless otherwise specified	Feb. 28, 2013	May 31, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 1,548,471	$ 1,576,928
Segment, Continuing Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	1,509,702	1,536,584
Segment, Continuing Operations | Cement Segment
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	1,166,156	1,135,336
Segment, Continuing Operations | Aggregates
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	168,696	178,730
Segment, Continuing Operations | Consumer Products
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	98,125	90,717
Segment, Continuing Operations | Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 76,725	$ 131,801