LONG-TERM DEBT - Summary of Components of Long-Term Debt and Capital Leases by Debt Instrument (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 487,802	$ 555,249
Finance leases maturing through December 2107; bearing interest at a weighted average of 5.3%	13,504
Less—unamortized discount and debt issuance costs	10,375	10,950
Long-term debt and finance leases less unamortized discount and debt issuance costs	477,427	544,299
Less—current maturities of long-term debt and finance leases	2,694	2,298
Non current portion of long term debt and capital lease obligation	$ 474,733	542,001
Weighted-average interest rate - finance leases	5.30%
Revolving line of credit facility (Revolving Credit Facility) due May 2023; bearing interest at LIBOR plus 2.00%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 0	$ 69,600
Revolving line of credit facility (Revolving Credit Facility) due May 2023; bearing interest at LIBOR plus 2.00% \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%	2.00%
Secured Debt \| Term loan A facility (Term Loan Facility) due May 2023; bearing interest at LIBOR plus 2.00%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 350,000	$ 350,000
Secured Debt \| Term loan A facility (Term Loan Facility) due May 2023; bearing interest at LIBOR plus 2.00% \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%	2.00%
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 (New York Bonds 2014) due December 2044 - fixed rate interest period through 2019; bearing interest at 3.75%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 25,000	$ 25,000
Less—unamortized discount and debt issuance costs	$ 801	$ 847
Stated interest rate	3.75%	3.75%
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 (New York Bonds 2014R-2) due December 2044 - fixed rate interest period through 2026; bearing interest at 3.125%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 15,000	$ 15,000
Less—unamortized discount and debt issuance costs	$ 435	$ 450
Stated interest rate	3.125%	3.125%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 (FAME Bonds 2005R-3) due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 25,000	$ 25,000
Less—unamortized discount and debt issuance costs	$ 496	$ 517
Stated interest rate	5.25%	5.25%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 (FAME Bonds 2015R-1) due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 15,000	$ 15,000
Less—unamortized discount and debt issuance costs	$ 604	$ 622
Stated interest rate	5.125%	5.125%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 (FAME Bonds 2015R-2) due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 15,000	$ 15,000
Less—unamortized discount and debt issuance costs	$ 474	$ 493
Stated interest rate	4.375%	4.375%
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 (Vermont Bonds) due April 2036 - fixed rate interest period through 2028; bearing interest at 4.625%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 16,000	$ 16,000
Less—unamortized discount and debt issuance costs	$ 581	$ 595
Stated interest rate	4.625%	4.625%
Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 (New Hampshire Bonds) due April 2029 - fixed rate interest period through 2019; bearing interest at 4.00%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 11,000	$ 11,000
Less—unamortized discount and debt issuance costs	$ 276	$ 308
Stated interest rate	4.00%	4.00%
Finance leases maturing through December 2107; bearing interest at a weighted average of 5.3%
Debt Instrument [Line Items]
Long-term debt and capital lease		$ 11,248
Weighted average interest rate		5.30%
Notes payable maturing through June 2027; bearing interest at a weighted average of 2.90%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 2,298	$ 2,401
Weighted average interest rate	2.90%	2.90%
Revolving Credit Facility and Term Loan Facility (collectively, the Credit Facility)
Debt Instrument [Line Items]
Less—unamortized discount and debt issuance costs	$ 6,708	$ 7,118

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
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