Acquisitions and Divestitures (Details) (Textuals) (USD $) In Millions, unless otherwise specified | 9 Months Ended | 12 Months Ended | 9 Months Ended | 9 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|---|---|---|
Sep. 30, 2011 | Sep. 30, 2010 | Dec. 31, 2010 | Sep. 30, 2010
Acquisition 2008 [Member] | Oct. 03, 2011
Broadcasting Group [Member] | Sep. 30, 2011
I&M [Member] | Dec. 31, 2010
S&P [Member] | Dec. 31, 2010
MHE [Member] | |
| Acquisitions and Divestitures (Textuals) [Abstract] | ||||||||
| Acquisitions, including contingent payments, net of cash acquired | $ 198.9 | $ 325.0 | ||||||
| Percentage of interest in acquired entity | 1.30% | |||||||
| Interest in local exchanges minimum | 5.00% | |||||||
| Business Acquisition (Textual) [Line Items] | ||||||||
| Contingent payment related to an acquisition | 5.0 | |||||||
| Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] | ||||||||
| Cash from divestiture of broadcasting group | 212 | |||||||
| Pre-tax gain (loss) on the divestiture | $ 11.1 | $ 13.2 | $ 7.3 | $ 3.8 | ||||