Property and Equipment - Historical Cost of Equipment and Other Property on Gross Basis with Accumulated Depreciation (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Gross equipment and other property	$ 20,273	$ 32,173
Accumulated depreciation	(5,237)	(8,801)
Net equipment and other property	15,036	23,372
Other equipment [Member]
Property Plant And Equipment [Line Items]
Gross equipment and other property	1,780	2,148
Inventory [Member]
Property Plant And Equipment [Line Items]
Gross equipment and other property	10,704	17,348
Gas gathering system and facilities [Member]
Property Plant And Equipment [Line Items]
Gross equipment and other property	145	4,790
Vehicles [Member]
Property Plant And Equipment [Line Items]
Gross equipment and other property	364	400
Leasehold improvements, office equipment and software [Member]
Property Plant And Equipment [Line Items]
Gross equipment and other property	$ 7,280	$ 7,487