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 | ||||