Quarterly report pursuant to Section 13 or 15(d)

Debt (Narrative) (Details)

v3.8.0.1
Debt (Narrative) (Details) - Line of Credit [Member] - USD ($)
3 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity $ 15,000,000  
Line of credit, amount outstanding 0 $ 0
Line of credit, remaining borrowing capacity $ 8,689,000  
Line of credit facility, interest rate at period end 3.90%  
Line of credit, expiration date Aug. 12, 2021  
Minimum liquidity $ 10,000,000  
LIBOR [Member]    
Debt Instrument [Line Items]    
Line of credit, basis spread on variable rate 2.00%