Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2014

Stockholders' Equity Note [Abstract]

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

The following table sets forth the change in the number of shares of our Class A common stock outstanding during the three months ended March 31, 2014 and during the fiscal year ended December 31, 2013:

	Three Months Ended		Twelve Months Ended
	March 31, 2014		December 31, 2013
Shares outstanding as of beginning of period	85.2		84.4
Shares issued as part of equity-based compensation plans and the Employee    Stock Purchase Plan ("ESPP"), net of restricted stock units surrendered	1.0		1.1
Common stock repurchases	(2.0	)	(0.3	)
Shares outstanding as of end of period	84.2		85.2