Stockholders' Deficit (Tables)

12 Months Ended

Dec. 31, 2017

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, 2017 and 2016:

	December 31,
	2017	2016
Shares outstanding as of beginning of period	88.0	86.5
Shares issued as part of equity-based compensation plans and the ESPP, net of shares surrendered	1.9	1.5
Shares outstanding as of end of period	89.9	88.0

RSUs outstanding under equity-based compensation plans

A summary of the changes in RSUs outstanding under our equity-based compensation plans during 2017 is presented below:

	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested RSUs as of December 31, 2016	4.9		$	11.68
Granted	0.9		$	22.55
Vested	(1.6	)	$	12.15
Cancelled	(0.3	)	$	16.25
Unvested RSUs as of December 31, 2017	3.9		$	13.73