Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Mar. 19, 2012
Income Taxes [Line Items]
Net (loss) income attributable to common and participating stockholders	$ (1,996,000)	$ (25,824,000)	$ (7,779,000)	$ (12,535,000)
Percentage of net operating loss carry forwards	100.00%		100.00%
Valuation allowance recorded to be reduce to	0.00%		0.00%
Income tax expense or benefit			$ 0			$ 0
Income tax at the federal statutory rate			21.00%			35.00%
Income tax paid			$ 0			$ 0
Reduction of deferred tax asset relating to NOL carry-forward			$ 842,900,000
Valuation allowance equal to net deferred federal income tax asset	100.00%		100.00%			100.00%
Abandoned stock							$ 8,400,000,000
Available and utilizable NOL carry forward						$ 6,000,000,000
NOLs expiration date			2031
Capital loss carryforward subject to expiration year			2018			2018
Reserves for uncertain federal income tax positions	$ 0		$ 0
Income tax interest income, expense or penalties			$ 0			$ 0
Income tax examination, year under examination			2011
Capital Loss Subject to Expiration in 2018
Income Taxes [Line Items]
Capital loss carryforward	$ 1,600,000		$ 1,600,000			$ 1,600,000
Scenario Plan [Member]
Income Taxes [Line Items]
Income tax at the federal statutory rate					21.00%