Treasury Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2012 Class A Common Stock [Member]	Mar. 31, 2011 Class A Common Stock [Member] Franklin Advisers, Inc. [Member]
Equity, Class of Treasury Stock [Line Items]
Shares withheld in payment of income tax withholding owed by employees (in shares)	5,358
Number of shares purchased (in shares)		49,332	4,500,000
Price per share paid (in dollars per share)		$ 55.18	$ 46.10
Total consideration of stock purchase		$ 3	$ 207