Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019	Dec. 31, 2019
Deferred compensation plan investments (1)	$ 119.4	[1]		$ 151.8
Participant Withdrawals From Deferred Compensation Plan Investments	37.2		$ 18.0
Level 1 [Member]
Deferred compensation plan investments (1)	119.4	[1]		151.8
Level 2 [Member]
Deferred compensation plan investments (1)	0.0	[1]		0.0
Level 3 [Member]
Deferred compensation plan investments (1)	$ 0.0	[1]		$ 0.0

[1] Approximately $37.2 million and $18.0 million of participant cash was withdrawn from our deferred compensation plan investments during the nine months ended September 30, 2020 and the year ended December 31, 2019, respectively.