v3.8.0.1
Income Taxes - Additional Information (Details) - USD ($)
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2017
Operating Loss Carryforwards [Line Items]      
Reversal of valuation allowance   $ 2,800,000  
Unrecognized tax benefits that would affect tax rate $ 0 0 $ 0
Tax Cuts And Jobs Act Of 2017, provisional non-cash tax benefit 111,300,000   111,300,000
State Tax Authority      
Operating Loss Carryforwards [Line Items]      
Operating loss carryforwards 2,500,000   2,500,000
Operating loss carryforwards, subject to annual limitations, Company 2,500,000   2,500,000
State income tax credit carryforward 2,900,000   2,900,000
Domestic Tax Authority      
Operating Loss Carryforwards [Line Items]      
Operating loss carryforwards 1,100,000   1,100,000
C Corporation | State Tax Authority      
Operating Loss Carryforwards [Line Items]      
Operating loss carryforwards 4,100,000   4,100,000
Operating loss carryforwards, subject to annual limitations, C corporation $ 4,100,000   $ 4,100,000
C Corporation | State Tax Authority | Operating Loss Carryforwards      
Operating Loss Carryforwards [Line Items]      
Valuation allowance   $ 200,000