v3.8.0.1
Credit Facility (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Credit Facility      
Credit Facility      
Amortization and interest expense capitalized $ 133 $ 234  
Amortization and interest expense expensed $ 47 $ 56  
Credit Facility | Maximum      
Credit Facility      
Interest rate percentage 4.20%    
Credit Facility | LIBOR | Minimum      
Credit Facility      
Spread on floating interest rate (as a percent) 2.50%    
Credit Facility | LIBOR | Maximum      
Credit Facility      
Spread on floating interest rate (as a percent) 3.50%    
Credit Facility | Prime Rate | Minimum      
Credit Facility      
Spread on floating interest rate (as a percent) 1.50%    
Credit Facility | Prime Rate | Maximum      
Credit Facility      
Spread on floating interest rate (as a percent) 2.50%    
Revolving Line of Credit      
Credit Facility      
Current issued borrowing capacity $ 69,750    
Maximum borrowing capacity with an option to increase the available amount upon the satisfaction of certain conditions 86,500    
Outstanding balance $ 0   $ 0
Revolving Line of Credit | Minimum      
Credit Facility      
Fee on unused portion of Revolving Line of Credit (as a percent) 0.375%    
Revolving Line of Credit | Maximum      
Credit Facility      
Fee on unused portion of Revolving Line of Credit (as a percent) 0.50%    
Term Loan      
Credit Facility      
Current issued borrowing capacity $ 3,500    
Outstanding balance $ 656   $ 875