ACQUISITIONS AND DIVESTITURES (Narrative) (Details) $ in Thousands		3 Months Ended				9 Months Ended		12 Months Ended
		Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) item	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Significant Acquisitions and Disposals [Line Items]
Cash consideration						$ (1,122)	$ 213,138
Number of facilities divested | item						2
Gain on sale of property, plant & equipment and businesses		$ 234		$ 2,104		$ 10,982	8,374
Assets held for sale		$ 0		$ 0		0	$ 0	$ 0
Goodwill increase	[1]					1,665
Acquisitions 2019 [Member]
Significant Acquisitions and Disposals [Line Items]
Total consideration						$ 0
Acquisitions 2018 [Member]
Significant Acquisitions and Disposals [Line Items]
Total consideration								219,863
Cash consideration								215,363
Consideration payable amount								4,500
Amortizable intangible assets recognized								$ 44,163
Intangible assets amortization period, tax purposes						15 years		15 years
Goodwill								$ 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
Goodwill increase						$ 1,665
Georgia [Member]
Significant Acquisitions and Disposals [Line Items]
Gain on sale of property, plant & equipment and businesses			$ 4,064		$ 2,929
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 - 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

[1] See Note 16 for a summary of prior year acquisitions.