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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
9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance $ 44,207 $ 41,041
Obligations incurred 2,187 1,828
Revisions in estimates 9,598 (56)
Accretion expense 3,164 2,688
Obligations settled (586) (601)
Ending balance $ 58,570 $ 44,900