Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

v3.19.2
Fair Value Measurements (Details) - USD ($)
$ in Thousands
6 Months Ended
Jun. 30, 2019
Dec. 31, 2018
Assets and liabilities measured at fair value on a recurring basis    
Marketable securities in deferred compensation plan $ 4,237 $ 3,868
Fair value measurement on a recurring basis | Deferred compensation plan | Trustees and Management    
Assets and liabilities measured at fair value on a recurring basis    
Maximum percentage of participants' compensation which is deferrable (as a percent) 100.00%  
Marketable securities in deferred compensation plan $ 4,200