Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2011

Stockholders' Equity

Schedule of change in the number of shares of Class A common stock

	Six Months	Twelve Months
	Ended	Ended
	June 30,	December 31,
	2011	2010
Shares outstanding as of beginning of period	91,725	93,883
Shares issued as part of equity-based compensation plans and the Employee Stock Purchase Plan (“ESPP”), net of RSUs surrendered	389	461
Shares repurchased into treasury stock	—	(2,619	)
Shares outstanding as of end of period	92,114	91,725