ACQUISITIONS AND DIVESTITURES (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended	1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Jan. 31, 2014
Significant Acquisitions and Disposals [Line Items]
Total consideration	$ 20,000,000		$ 331,836,000
Payment for acquisition of businesses			284,237,000
Exchanges of real property and businesses			2,414,000
Cash proceeds from divestiture	0	720,056,000
Gain on sale of properties and businesses	6,375,000	236,364,000
Supply agreement period	20 years
Purchases of property, plant & equipment	49,611,000	46,006,000
Property, plant & equipment	6,671,537,000	6,340,034,000	6,608,842,000
Proceeds from sale of property, plant & equipment	2,354,000	17,785,000
Consideration transferred, common stock			45,185,000
Common stock issued in connection with business acquisitions			715,004
Aggregates [Member]
Significant Acquisitions and Disposals [Line Items]
Gain on sale of properties and businesses				5,790,000
Proceeds from sale of property, plant & equipment		5,820,000
Aggregates [Member] | ARIZONA AND NEW MEXICO [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired			5
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]
Gain on sale of properties and businesses		168,000
Proceeds from sale of property, plant & equipment		10,727,000
California ready-mixed concrete operations [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized	7,168,000
Estimated weighted-average amortization period of intangible assets	20 years
Intangible assets amortization period, tax purposes	15 years
California ready-mixed concrete operations [Member] | CALIFORNIA [Member]
Significant Acquisitions and Disposals [Line Items]
Total consideration	20,000,000
Gain on sale of properties and businesses	$ 5,886,000
Number of facilities divested	12
Asphalt mix plants [Member] | ARIZONA [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired	13
Asphalt plants and Aggregates facilities [Member] | Asphalt And Aggregates [Member] | CALIFORNIA [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired			2
Asphalt plants and Aggregates facilities [Member] | Aggregates [Member] | CALIFORNIA [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired			4
Asphalt plants and Aggregates facilities [Member] | Aggregates [Member] | DELAWARE [Member]
Significant Acquisitions and Disposals [Line Items]
Number of facilities acquired	2