REMEDIAL LIABILITIES (Changes in Remedial Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Changes to remedial liabilities
Balance at the beginning of the period	$ 124,468	$ 128,007
Measurement period adjustments from prior period acquisitions		504
Accretion	4,702	4,712
Changes in estimates recorded to statement of operations	687	45
Expenditures	(7,834)	(9,740)
Currency translation and other	(1,006)	940
Balance at the end of the period	121,017	124,468
Remedial Liabilities for Landfill Sites
Changes to remedial liabilities
Balance at the beginning of the period	1,800	1,777
Measurement period adjustments from prior period acquisitions		0
Accretion	86	86
Changes in estimates recorded to statement of operations	(1)	(21)
Expenditures	(47)	(42)
Currency translation and other	0	0
Balance at the end of the period	1,838	1,800
Remedial Liabilities for Inactive Sites
Changes to remedial liabilities
Balance at the beginning of the period	65,342	64,151
Measurement period adjustments from prior period acquisitions		0
Accretion	2,745	2,648
Changes in estimates recorded to statement of operations	130	(289)
Expenditures	(3,759)	(3,906)
Currency translation and other	857	2,738
Balance at the end of the period	65,315	65,342
Remedial Liabilities (Including Superfund) for Non-Landfill Operations
Changes to remedial liabilities
Balance at the beginning of the period	57,326	62,079
Measurement period adjustments from prior period acquisitions		504
Accretion	1,871	1,978
Changes in estimates recorded to statement of operations	558	355
Expenditures	(4,028)	(5,792)
Currency translation and other	(1,863)	(1,798)
Balance at the end of the period	$ 53,864	$ 57,326