Noncash Investing and Financing Activities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Cash Flow Elements [Abstract]
Acquisition of assets through asset exchange	$ 2,091		$ 690
Acquisition of assets through capital lease	7,788	10,341
Seller financing of land purchase	1,500
Acquisition of TXI net assets assumed through issuances of common stock and options (See Note C)	$ 2,691,986

Amount of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 7

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Future cash outflow to pay for purchases of fixed assets that have occurred.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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