Stockholders' Equity (Details)	12 Months Ended
	Dec. 31, 2012 item
Class A common stock
Stockholders Equity (Deficit)
Votes per share	1
Class B common stock
Stockholders Equity (Deficit)
Votes per share	10
Number of shares of Class A common stock into which each share of common stock is convertible	1
Class C common stock
Stockholders Equity (Deficit)
Votes per share	1
Number of shares of Class A common stock into which each share of common stock is convertible	1
Votes per share in event of change of control	10