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Income Taxes - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Income Taxes [Line Items]    
U.S. federal statutory tax rate, percent 21.00% 35.00%
Limitation of taxable income for NOL carryforward percentage 80.00%  
Tax cuts and jobs act description On December 22, 2017, the President of the United States signed into law Public Law No. 115-97, commonly referred to as the Tax Reform Act, following its passage by the United States Congress. The Tax Act made significant changes to U.S. federal income tax laws, including reduction of the corporate tax rate from 35.0% to 21.0%, limitation of the deduction for net operating losses to 80.0% of current year taxable income and elimination of net operating loss carrybacks, one-time taxation of offshore earning at reduced rates regardless of whether they are repatriated, elimination of U.S. tax on foreign earnings (subject to certain important exceptions), immediate deductions for certain new investments instead of deductions for depreciation expense over time, and modifying or repealing many business deductions.  
Income tax expense from discontinued operations   $ 23,299,000
Uncertain income tax positions $ 0  
Federal    
Income Taxes [Line Items]    
Net operating loss carryforwards 96,400,000 41,500,000
State    
Income Taxes [Line Items]    
Net operating loss carryforwards 44,500,000 20,200,000
Tax credit carryforwards $ 700,000 $ 500,000
Earliest Tax Year | Federal    
Income Taxes [Line Items]    
Operating losses, begin to expiration year 2037  
Tax credits, begin to expiration year 2037