Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Details)

v3.8.0.1
Income Taxes - Additional Information (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax Expense (Benefit), Continuing Operations [Abstract]        
Federal statutory income tax rate   35.00% 35.00% 35.00%
Cash paid for income taxes   $ 185 $ 310 $ 390
Income tax refund received   11,906 7,796 $ 90
Current income taxes receivable $ 13,006 13,006 11,943  
Non-current income taxes receivable 52,097 52,097 52,097  
Increase and (decrease) in valuation allowance $ (105,900) $ (118,600) 52,900  
Minimum        
Income Tax Expense (Benefit), Continuing Operations [Abstract]        
Tax years under examination   2013    
Maximum        
Income Tax Expense (Benefit), Continuing Operations [Abstract]        
Tax years under examination   2017    
Tax Year 2016 and 2017        
Income Tax Expense (Benefit), Continuing Operations [Abstract]        
Income tax refund received related to NOL claim   $ 11,900 $ 7,800