Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021		Sep. 30, 2020	Dec. 31, 2020
Deferred compensation plan investments (1)	$ 131.7	[1]		$ 129.8
Participant Withdrawals From Deferred Compensation Plan Investments	10.4		$ 37.8
Level 1 [Member]
Deferred compensation plan investments (1)	131.7	[1]		129.8
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[1] Approximately $10.4 million and $37.8 million of participant cash was withdrawn from our deferred compensation plan investments during the nine months ended September 30, 2021 and the year ended December 31, 2020, respectively.