Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,339		$ 1,339		$ 1,353
Accumulated Amortization	(932)		(932)		(713)
Net	407		$ 407		$ 640
Remaining Useful Life (Years)			3 years 1 month		2 years 9 months 24 days
Write-off of disposal permits					$ 27
Amortization of intangible assets	100	$ 100	$ 200	$ 200
Disposal permits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	540		540		554
Accumulated Amortization	(311)		(311)		(269)
Net	229		$ 229		$ 285
Remaining Useful Life (Years)			4 years 11 months 15 days		5 years
Trade name
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	799		$ 799		$ 799
Accumulated Amortization	(621)		(621)		(444)
Net	$ 178		$ 178		$ 355
Remaining Useful Life (Years)			7 months		1 year