Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

v3.10.0.1
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, 2017
Income Taxes [Line Items]          
U.S. federal statutory tax rate     21.00%    
Percentage of TCJA limitations on net operating loss carryforwards to taxable income     80.00%    
Maximum          
Income Taxes [Line Items]          
U.S. federal statutory tax rate         35.00%
Federal          
Income Taxes [Line Items]          
Net operating loss carryforwards     $ 60,600,000    
Net operating loss carryforwards expiration period     carried forward for 20 years and are expected to be available to fully offset taxable income earned in future tax years.    
Current income tax expense benefit $ 0 $ 0 $ 0 $ 0  
Deferred income tax expense benefit 0 $ 0 0 $ 0  
Federal and State          
Income Taxes [Line Items]          
Net operating loss carryforwards $ 60,600,000   $ 60,600,000