Goodwill And Intangible Assets (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Goodwill	$ 1,172.2		$ 1,172.2		$ 1,142.4
Franchise rights - indefinite-lived	212.6		212.6		199.1
Other intangibles	8.4		8.4		5.6
Intangible Assets Gross (Excluding Goodwill)	221.0		221.0		204.7
Less: accumulated amortization	(3.0)		(3.0)		(2.7)
Other intangible assets, net	218.0		218.0		202.0
Goodwill impairment	0	0	0	0
Franchise rights impairment	$ 0	$ 0	$ 0	$ 0
Date Of Annual Goodwill Impairment Test [Member]
Date of annual goodwill and indefinite lived intangible assets impairment test			April 30
Date of Annual Indefinite Lived Intangible Assets Impairment Test [Member]
Date of annual goodwill and indefinite lived intangible assets impairment test			April 30