Segment Information - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
Sep. 30, 2013 Segment
Segment Reporting Information [Line Items]
Business segments	4
Cement plant locations	6
Cement distribution terminals	16
Gypsum wallboard plants	5
Aggregates processing plant	4
Readymix concrete batch plant	17
Proportionate consolidation of share of Joint Venture's revenues and operating earnings	50.00%
Operating Segments [Member] \| Gypsum Wallboard [Member]
Segment Reporting Information [Line Items]
Carrying value of plant	$ 3.0
Carrying value of equipment	$ 2.2

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

No definition available.

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration