Financial Instruments (Carrying Value, Fair Value And Hierarchy Of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
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	$ 72,296	$ 77,446
Total debt	160,000	90,000
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	72,296	77,446
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	$ 160,000	$ 90,000