Intangible Assets (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,353,000		$ 1,353,000
Accumulated Amortization	(827,000)		(713,000)
Net	$ 526,000		$ 640,000
Remaining Useful Life (Years)	2 years 10 months 25 days		2 years 9 months 24 days
Write-off of disposal permits			$ 27,000
Amortization of intangible assets	$ 100,000	$ 100,000
Disposal permits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	554,000		554,000
Accumulated Amortization	(294,000)		(269,000)
Net	$ 260,000		$ 285,000
Remaining Useful Life (Years)	4 years 10 months 25 days		5 years
Trade name
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 799,000		$ 799,000
Accumulated Amortization	(533,000)		(444,000)
Net	$ 266,000		$ 355,000
Remaining Useful Life (Years)	9 months 25 days		1 year