XML 43 R31.htm IDEA: XBRL DOCUMENT v3.19.2
Fair Value of Financial Instruments (Narrative) (Details) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Fair Value of Financial Instruments [Abstract]          
Investment maturity term     1 year    
Fair value of investments in rabbi trust $ 12,283,000   $ 12,283,000   $ 10,872,000
Impairment charge, Held-to-maturity Securities $ 0 $ 0 $ 0 $ 0