Stockholders' Equity (Tables)

12 Months Ended

Dec. 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 Class A common stock outstanding during the fiscal years ended December 31, 2014 and 2013:

	December 31,
	2014		2013
Shares outstanding as of beginning of period	85.2		84.4
Shares issued as part of equity-based compensation plans and the ESPP, net of shares surrendered	1.9		1.1
Shares repurchased into treasury stock	(2.0	)	(0.3	)
Shares outstanding as of end of period	85.1		85.2