Stockholders' Equity (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2010
Common Stock Repurchase Program
Value of shares repurchased		$ 605,000
Class A common stock
Common Stock Repurchase Program
Amount of shares authorized for repurchase	500,000,000
Number of shares repurchased		34,000
Value of shares repurchased		605,000
Amount of shares that may be repurchased	$ 500,000,000