Related Party Transactions - Management Agreement (Details) - SP General Services LLC - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Mar. 31, 2015
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Related Party Transaction [Line Items]            
Management fee percentage, quarterly basis (as a percent)       1.50%    
Management agreement renewal, term (in years)       1 year    
Notice period prior to management agreement renewal, period (in days)       60 days    
Management Fee            
Related Party Transaction [Line Items]            
Services fees and reimbursable expenses $ 2,172 $ 2,148   $ 6,387 $ 6,188  
Reimbursable Expenses            
Related Party Transaction [Line Items]            
Services fees and reimbursable expenses 859 $ 448   3,095 $ 1,903  
Deferred fees payable to related party $ 888     $ 888   $ 695
Related Party Debt            
Related Party Transaction [Line Items]            
Settlement of debt     $ 1,800