CLOSURE AND POST-CLOSURE LIABILITIES (Changes in Post-Closure Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Changes to post-closure liabilities
Balance at the beginning of the period	$ 61,037	$ 58,331
Liabilities assumed in acquisitions	685	59
Measurement period adjustments from prior period acquisitions		596
New asset retirement obligations	2,518	1,881
Adjustment related to disposition of business	(5,104)	(1,170)
Accretion		4,748
Changes in estimates recorded to statement of operations	1,460	(240)
Changes in estimates recorded to balance sheet	1,931	(227)
Expenditures	(2,281)	(3,225)
Currency translation and other	(523)	284
Balance at the end of the period	69,931	$ 61,037
Increase in facility closure costs	$ 1,200
Asset retirement obligations, risk free rate (as a percent)	5.66%	6.32%
Landfill Retirement Liability
Changes to post-closure liabilities
Balance at the beginning of the period	$ 32,382	$ 30,630
Liabilities assumed in acquisitions	0	0
Measurement period adjustments from prior period acquisitions		0
New asset retirement obligations	2,518	1,881
Adjustment related to disposition of business	(2,537)	0
Accretion		2,243
Changes in estimates recorded to statement of operations	(37)	(131)
Changes in estimates recorded to balance sheet	1,867	364
Expenditures	(1,224)	(2,777)
Currency translation and other	(234)	172
Balance at the end of the period	37,809	32,382
Non-Landfill Retirement Liability
Changes to post-closure liabilities
Balance at the beginning of the period	28,655	27,701
Liabilities assumed in acquisitions	685	59
Measurement period adjustments from prior period acquisitions		596
New asset retirement obligations	0	0
Adjustment related to disposition of business	(2,567)	(1,170)
Accretion		2,505
Changes in estimates recorded to statement of operations	1,497	(109)
Changes in estimates recorded to balance sheet	64	(591)
Expenditures	(1,057)	(448)
Currency translation and other	(289)	112
Balance at the end of the period	$ 32,122	$ 28,655