Stockholders' Deficit (Tables)

12 Months Ended

Dec. 31, 2018

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 common stock outstanding during the fiscal years ended December 31, 2018 and 2017:

	December 31,
	2018	2017
Shares outstanding as of beginning of period	89.9	88.0
Shares issued as part of equity-based compensation plans and the ESPP, net of shares surrendered	2.0	1.9
Shares outstanding as of end of period	91.9	89.9

RSUs outstanding under equity-based compensation plans

A summary of the changes in RSUs outstanding under our equity-based compensation plans during 2018 is presented below:

	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested RSUs as of December 31, 2017	3.9		$	13.73
Granted	1.1		$	47.17
Vested	(2.1	)	$	15.45
Cancelled	(0.3	)	$	22.02
Unvested RSUs as of December 31, 2018	2.6		$	25.37