ACQUISITIONS AND DIVESTITURES (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended			12 Months Ended			24 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Significant Acquisitions and Disposals [Line Items]
Total consideration						$ 219,863
Cash consideration					$ 44,151	221,419	$ 1,109,725
Consideration payable amount						4,500
Goodwill	[1]				1,665	43,075
Gain on sale of property, plant & equipment and businesses		$ 4,064			23,752	14,944	17,827
Assets held for sale				$ 0	0	0	0	$ 0
Aggregates USA [Member]
Significant Acquisitions and Disposals [Line Items]
Gain on sale of property, plant & equipment and businesses				0
Acquisitions 2019 [Member]
Significant Acquisitions and Disposals [Line Items]
Total consideration					45,273
Amortizable intangible assets recognized					$ 25,443
Intangible assets amortization period, tax purposes					15 years
Acquisitions 2018 [Member]
Significant Acquisitions and Disposals [Line Items]
Total consideration						219,863
Cash consideration						215,363
Cash						215,363
Amortizable intangible assets recognized						44,163
Intangible assets amortization period, tax purposes					15 years
Goodwill						42,325		43,990
Intangible assets, deductible for income tax purposes						7,385
Goodwill, deductible for income tax purposes						4,863
Deferred income taxes, net					$ 31,721	32,871		$ 31,721
Goodwill increase					1,665
Proceeds from working capital adjustment					$ 1,122
Acquisitions 2017 [Member]
Significant Acquisitions and Disposals [Line Items]
Consideration transferred, net of assets divested							793,523
Amortizable intangible assets recognized							309,112
Intangible assets amortization period, tax purposes					15 years
Goodwill, deductible for income tax purposes				28,247			28,247
Acquisitions 2017 [Member] | Aggregates USA [Member]
Significant Acquisitions and Disposals [Line Items]
Amount of assets divested				287,292			287,292
Immaterial Business Acquisitions [Member]
Significant Acquisitions and Disposals [Line Items]
Total consideration							48,490
Cash consideration							36,746
Consideration payable amount							1,844
Assets acquired				9,900			9,900
Arizona [Member]
Significant Acquisitions and Disposals [Line Items]
Gain on sale of property, plant & equipment and businesses				8,021
Assets divested, fair value				9,900			9,900
Assets held for sale				$ 1,879			1,879
Georgia [Member]
Significant Acquisitions and Disposals [Line Items]
Gain on sale of property, plant & equipment and businesses			$ 2,929
Contractual Rights In Place [Member] | Acquisitions 2017 [Member]
Significant Acquisitions and Disposals [Line Items]
Intangible assets amortization period, tax purposes					15 years
Contractual Rights In Place - Straight-Line Method [Member] | Acquisitions 2019 [Member]
Significant Acquisitions and Disposals [Line Items]
Estimated weighted-average amortization period of intangible assets					19 years 6 months
Contractual Rights In Place - Straight-Line Method [Member] | Acquisitions 2018 [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized						43,072
Estimated weighted-average amortization period of intangible assets					19 years 10 months 24 days
Contractual Rights In Place - Straight-Line Method [Member] | Acquisitions 2017 [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized							73,879
Estimated weighted-average amortization period of intangible assets					19 years 3 months 18 days
Contractual Rights In Place - Units Of Sales [Member] | Acquisitions 2018 [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized						$ 1,080
Estimated weighted-average amortization period of intangible assets					30 years
Contractual Rights In Place - Units Of Sales [Member] | Acquisitions 2017 [Member]
Significant Acquisitions and Disposals [Line Items]
Amortizable intangible assets recognized							$ 235,133
Estimated weighted-average amortization period of intangible assets					54 years 8 months 12 days

[1] See Note 19 for a summary of recent acquisitions.