SEGMENT REPORTING - Summary of Financial Information by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 172,832	$ 160,269	$ 485,936	$ 448,087
Depreciation and amortization	18,202	16,591	51,572	46,307
Operating income (loss)	28,884	18,277	44,871	(22,437)
Total assets	702,848		702,848		$ 614,949
Operating Segments
Segment Reporting Information [Line Items]
Revenues	172,832	160,269	485,936	448,087
Depreciation and amortization	18,202	16,591	51,572	46,307
Operating income (loss)	28,884	18,277	44,871	(22,437)
Total assets	702,848	592,420	702,848	592,420
Operating Segments \| Eastern
Segment Reporting Information [Line Items]
Revenues	56,006	49,066	154,099	134,326
Depreciation and amortization	7,267	6,122	20,276	17,949
Operating income (loss)	15,370	5,897	17,824	(54,407)
Total assets	180,896	155,726	180,896	155,726
Operating Segments \| Western
Segment Reporting Information [Line Items]
Revenues	74,425	67,992	210,208	186,507
Depreciation and amortization	8,844	8,572	25,226	22,762
Operating income (loss)	14,144	11,579	33,325	26,438
Total assets	402,931	335,373	402,931	335,373
Operating Segments \| Recycling
Segment Reporting Information [Line Items]
Revenues	10,877	16,360	30,634	49,206
Depreciation and amortization	1,131	1,044	3,228	3,066
Operating income (loss)	(481)	638	(7,898)	3,285
Total assets	48,995	49,471	48,995	49,471
Operating Segments \| Other
Segment Reporting Information [Line Items]
Revenues	31,524	26,851	90,995	78,048
Depreciation and amortization	960	853	2,842	2,530
Operating income (loss)	(149)	163	1,620	2,247
Total assets	70,026	51,850	70,026	51,850
Eliminations
Segment Reporting Information [Line Items]
Revenues	(37,363)	(33,718)	(106,401)	(91,345)
Eliminations \| Eastern
Segment Reporting Information [Line Items]
Revenues	14,557	14,296	40,432	37,020
Eliminations \| Western
Segment Reporting Information [Line Items]
Revenues	20,578	19,183	59,898	53,590
Eliminations \| Recycling
Segment Reporting Information [Line Items]
Revenues	1,773	(292)	4,697	(781)
Eliminations \| Other
Segment Reporting Information [Line Items]
Revenues	$ 455	$ 531	$ 1,374	$ 1,516

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: 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(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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