Income Taxes - Narrative (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Income Tax Contingency [Line Items]    
Decrease in valuation allowance $ 8,800  
Federal income tax rate 34.00%  
Uncertain tax positions accrued $ 0 $ 0
Accrued interest and penalties related to uncertain tax positions $ 0 $ 0
Maximum    
Income Tax Contingency [Line Items]    
Federal income tax rate 35.00%  
Federal.    
Income Tax Contingency [Line Items]    
Net operating loss carryforwards $ 68,700  
State.    
Income Tax Contingency [Line Items]    
Net operating loss carryforwards $ 500