ACQUISITIONS AND DIVESTITURES (Narrative) (Details)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2015 USD ($) property	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) item property shares
Significant Acquisitions and Disposals [Line Items]
Proceeds from sale of property, plant & equipment				$ 3,419,000	$ 20,454,000
Total consideration						$ 331,836,000
Payment for acquisition of businesses				21,387,000	207,000	284,237,000
Exchanges of real property and businesses						2,414,000
Gain on sale of properties and businesses	$ 249,000	$ 1,162,000		$ 6,624,000	237,526,000
Supply agreement period				20 years
Purchases of property, plant & equipment				$ 148,721,000	$ 116,312,000
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
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
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]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized				$ 16,543,000
Intangible assets amortization period, tax purposes				15 years
California ready-mixed concrete operations [Member] | CALIFORNIA [Member]
Significant Acquisitions and Disposals [Line Items]
Total consideration				$ 41,387,000
Payment for acquisition of businesses				21,387,000
Exchanges of real property and businesses				20,000,000
Gain on sale of properties and businesses				$ 5,886,000
Number of facilities divested | property				12
California ready-mixed concrete operations [Member] | Straight Line Method [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized				$ 7,168,000
Estimated weighted-average amortization period of intangible assets				20 years
California ready-mixed concrete operations [Member] | Unit Of Production Method [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized				$ 9,375,000
Estimated weighted-average amortization period of intangible assets				50 years
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