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ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE - Summary of Changes to Accrued Capping, Closure and Post-Closure Liabilities (Detail) - USD ($)
$ in Thousands
6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance $ 73,075 $ 62,290
Obligations incurred 1,217 1,793
Revision in estimates 0 1,492
Accretion expense 3,194 2,784
Obligations settled (2,947) (614)
Ending balance $ 74,539 $ 67,745