Property, Plant and Equipment - Schedule of Property Plant and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 88,847	$ 87,263	$ 85,680
Less: accumulated depreciation	(25,242)	(20,657)	(11,969)
Property, plant and equipment, net	63,605	66,606	73,711
Liquefaction Plants And Systems [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	40,573	39,679	39,679
Real Property And Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,396	1,396	1,396
Vehicles and tanker trailers and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	45,274	44,878	43,407
Computer And Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	250	238	216
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,353	1,071	880
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1	$ 1	$ 101

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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