XML 69 R56.htm IDEA: XBRL DOCUMENT v3.21.1
Financial Instruments (Carrying Value, Fair Value And Hierarchy Of Financial Instruments) (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Carrying Value [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Mutual fund investments of deferred compensation plans held in trust $ 93,705 $ 88,811
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Mutual fund investments of deferred compensation plans held in trust $ 93,705 $ 88,811