CLOSURE AND POST-CLOSURE LIABILITIES (Changes in Post-Closure Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes to post-closure liabilities
Balance at the beginning of the period	$ 58,331	$ 56,249
Liabilities assumed in acquisitions	59	2,408
Measurement period adjustments from prior period acquisitions	596	657
New asset retirement obligations	1,881	1,983
Measurement period adjustments from prior period acquisitions	(1,170)
Accretion	4,748	5,103
Changes in estimates recorded to statement of operations	(240)	(2,619)
Changes in estimates recorded to balance sheet	(227)	(3,289)
Expenditures	(3,225)	(2,248)
Currency translation and other	284	87
Balance at the end of the period	$ 61,037	$ 58,331
Asset retirement obligations discount rate	6.32%	6.23%
Landfill Retirement Liability
Changes to post-closure liabilities
Balance at the beginning of the period	$ 30,630	$ 32,023
Liabilities assumed in acquisitions	0	0
Measurement period adjustments from prior period acquisitions	0	0
New asset retirement obligations	1,881	1,983
Measurement period adjustments from prior period acquisitions	0
Accretion	2,243	2,705
Changes in estimates recorded to statement of operations	(131)	(1,415)
Changes in estimates recorded to balance sheet	364	(3,289)
Expenditures	(2,777)	(1,446)
Currency translation and other	172	69
Balance at the end of the period	32,382	30,630
Non-Landfill Retirement Liability
Changes to post-closure liabilities
Balance at the beginning of the period	27,701	24,226
Liabilities assumed in acquisitions	59	2,408
Measurement period adjustments from prior period acquisitions	596	657
Measurement period adjustments from prior period acquisitions	(1,170)
Accretion	2,505	2,398
Changes in estimates recorded to statement of operations	(109)	(1,204)
Changes in estimates recorded to balance sheet	(591)	0
Expenditures	(448)	(802)
Currency translation and other	112	18
Balance at the end of the period	$ 28,655	$ 27,701