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 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.18)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 12
-Article 7

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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=56944662&loc=d3e3602-108585

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The net result for the period of deducting operating expenses from operating revenues.

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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=26872669&loc=d3e20235-122688

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Segment Reporting - Summary of Financial Information by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Inter-company revenues	$ 125,432	$ 116,577
Depreciation and amortization	14,453	13,748
Operating income (loss)	1,974	3,126
Total assets	620,406	636,381	$ 633,669
Eastern Region [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	6,190	5,237
Operating income (loss)	(788)	(485)
Total assets	209,315	205,062
Western Region [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	6,490	6,738
Operating income (loss)	2,993	4,995
Total assets	312,369	325,799
Recycling [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	1,092	1,116
Operating income (loss)	(1,074)	(2,010)
Total assets	48,042	50,157
Other [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	681	657
Operating income (loss)	843	626
Total assets	50,680	55,363
Outside Revenues [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	125,432	116,577
Outside Revenues [Member] \| Eastern Region [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	38,987	33,267
Outside Revenues [Member] \| Western Region [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	52,462	49,357
Outside Revenues [Member] \| Recycling [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	10,638	10,294
Outside Revenues [Member] \| Other [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	23,345	23,659
Inter-Company Revenue [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	(25,299)	(22,639)
Inter-Company Revenue [Member] \| Eastern Region [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	9,536	8,016
Inter-Company Revenue [Member] \| Western Region [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	14,852	14,398
Inter-Company Revenue [Member] \| Recycling [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	631	4
Inter-Company Revenue [Member] \| Other [Member]
Segment Reporting Information [Line Items]
Inter-company revenues	$ 280	$ 221