ACQUISITIONS AND DIVESTITURES (Narrative) (Details)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2015 USD ($) property	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) item property shares
Significant Acquisitions and Disposals [Line Items]
Proceeds from sale of property, plant & equipment				$ 4,464,000	$ 21,320,000
Total consideration				40,801,000		$ 331,836,000
Payment for acquisition of businesses				20,801,000	268,604,000	284,237,000
Exchanges of real property and businesses						2,414,000
Amortizable intangible assets recognized				$ 16,176,000
Intangible assets amortization period, tax purposes				15 years
Gain on sale of properties and businesses	$ 799,000	$ 1,002,000		$ 7,423,000	238,527,000
Supply agreement period				20 years
Purchases of property, plant & equipment				$ 214,815,000	$ 169,220,000
Consideration transferred, common stock						$ 45,185,000
Common stock issued in connection with business acquisitions | shares						715,004
Dallas/Fort Worth [Member]
Significant Acquisitions and Disposals [Line Items]
Number of distribution yard acquired | property						2
Aggregates [Member]
Significant Acquisitions and Disposals [Line Items]
Proceeds from sale of property, plant & equipment			$ 5,820,000
Gain on sale of properties and businesses			5,790,000
Aggregates [Member] | ARIZONA AND NEW MEXICO [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired | property				3		5
Concrete [Member] | ARIZONA AND NEW MEXICO [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired | property				7
Asphalt Mix [Member] | ARIZONA [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired | property				13
Exchanges of real property and businesses				$ 20,000,000
Cement And Concrete [Member]
Significant Acquisitions and Disposals [Line Items]
Gain on sale of properties and businesses			227,910,000
Total consideration			721,359,000
Aggregates and Concrete [Member] | ARIZONA AND NEW MEXICO [Member]
Significant Acquisitions and Disposals [Line Items]
Payment for acquisition of businesses				20,801,000
Straight Line Method [Member] | Asphalt Mix [Member] | ARIZONA [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized				$ 7,168,000
Estimated weighted-average amortization period of intangible assets				20 years
Unit Of Production Method [Member] | Aggregates and Concrete [Member] | ARIZONA AND NEW MEXICO [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized				$ 9,008,000
Estimated weighted-average amortization period of intangible assets				50 years
Previously mined and subsequently reclaimed tract of land [Member] | Aggregates [Member]
Significant Acquisitions and Disposals [Line Items]
Proceeds from sale of property, plant & equipment			10,727,000
Gain on sale of properties and businesses			$ 168,000
California ready-mixed concrete operations [Member] | CALIFORNIA [Member]
Significant Acquisitions and Disposals [Line Items]
Gain on sale of properties and businesses				$ 5,886,000
Number of facilities divested | property				12
Asphalt plants and Aggregates facilities [Member] | Asphalt And Aggregates [Member] | CALIFORNIA [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired | property						2
Asphalt plants and Aggregates facilities [Member] | Aggregates [Member] | CALIFORNIA [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired | property						4
Asphalt plants and Aggregates facilities [Member] | Aggregates [Member] | DELAWARE [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired | property						2
Rail-connected aggregates operation [Member] | Dallas/Fort Worth [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired | item						1
Permitted aggregates quarry [Member] | Alabama [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired | item						1