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Segment Reporting - Summary of Revenue Attributable to Services Provided by Company (Detail) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended														8 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Dec. 31, 2014	Dec. 31, 2015	Apr. 30, 2014	Apr. 30, 2013
Revenue from External Customer [Line Items]
Revenues	$ 85,646	$ 140,024	$ 146,185	$ 143,714	$ 116,577	$ 141,341	$ 141,387	$ 118,927	$ 117,852	$ 132,296	$ 128,558	$ 108,694	$ 112,167	$ 116,836	$ 117,638	$ 368,374	$ 546,500	$ 497,633	$ 455,335
Revenues percentage																100.00%	100.00%	100.00%	100.00%
Solid Waste Operations Collection [Member]
Revenue from External Customer [Line Items]
Revenues																$ 157,809	$ 238,301	$ 225,441	$ 208,973
Revenues percentage																42.80%	43.60%	45.30%	45.90%
Solid Waste Operations Disposal [Member]
Revenue from External Customer [Line Items]
Revenues																$ 102,304	$ 156,536	$ 128,778	$ 115,049
Revenues percentage																27.80%	28.60%	25.90%	25.30%
Solid Waste Operations Power Generation [Member]
Revenue from External Customer [Line Items]
Revenues																$ 5,049	$ 6,796	$ 9,512	$ 11,354
Revenues percentage																1.40%	1.20%	1.90%	2.40%
Solid Waste Operations Processing [Member]
Revenue from External Customer [Line Items]
Revenues																$ 6,643	$ 6,061	$ 8,852	$ 6,901
Revenues percentage																1.80%	1.10%	1.80%	1.50%
Solid Waste Operations [Member]
Revenue from External Customer [Line Items]
Revenues																$ 271,805	$ 407,694	$ 372,583	$ 342,277
Revenues percentage																73.80%	74.50%	74.90%	75.10%
Organics [Member]
Revenue from External Customer [Line Items]
Revenues																$ 27,012	$ 39,134	$ 37,829	$ 35,330
Revenues percentage																7.30%	7.20%	7.60%	7.80%
Customer Solutions [Member]
Revenue from External Customer [Line Items]
Revenues																$ 35,816	$ 53,334	$ 43,396	$ 35,455
Revenues percentage																9.70%	9.80%	8.70%	7.80%
Recycling [Member]
Revenue from External Customer [Line Items]
Revenues																$ 33,741	$ 46,338	$ 43,825	$ 42,273
Revenues percentage																9.20%	8.50%	8.80%	9.30%

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=51801978&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13531-108611

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-Name Accounting Standards Codification
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 225
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-Section S99
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