Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

v3.8.0.1
Fair Value Measurements (Details) - Recurring basis - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Level 1 - Quoted Prices in Active Markets for Identical Assets    
Fair value    
Trading investment securities $ 1,753 $ 1,980
Total assets measured at fair value on a recurring basis 1,753 1,980
Level 2 - Significant Other Observable Inputs    
Fair value    
Trading investment securities 0 0
Total assets measured at fair value on a recurring basis 0 0
Level 3 - Significant Unobservable Inputs    
Fair value    
Trading investment securities 0 0
Total assets measured at fair value on a recurring basis 0 0
Total    
Fair value    
Trading investment securities 1,753 1,980
Total assets measured at fair value on a recurring basis $ 1,753 $ 1,980