STOCKHOLDERS' EQUITY (Tables)

9 Months Ended

Sep. 30, 2017

Stockholders' Equity Note [Abstract]

Schedule of Stock by Class

The following table presents the number of shares authorized and issued and outstanding as of the dates indicated:

	September 30, 2017		December 31, 2016
	Shares Authorized	Shares Issued and Outstanding	Shares Authorized	Shares Issued and Outstanding
Stockholders’ equity:
Common stock, $0.000001 par value	200,000,000	82,741,466	200,000,000	79,429,833
Undesignated Preferred Stock	10,000,000	—	10,000,000	—

Schedule of Stock Option Activity

A summary of stock option activity for the nine months ended September 30, 2017 is as follows:

	Options Outstanding
	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding - December 31, 2016	8,018,941		$	21.71	6.10	$	147,673
Granted	920,850		34.60
Exercised	(1,216,110	)	19.85
Canceled	(210,770	)	47.08
Outstanding - September 30, 2017	7,512,911		$	22.88	5.85	$	162,770
Options vested and exercisable as of September 30, 2017	5,904,796		$	20.32	5.05	$	143,342

Schedule of RSU Activity

A summary of RSU activity for the nine months ended September 30, 2017 is as follows:

	Restricted Stock Units
	Number of Shares		Weighted- Average Grant Date Fair Value
Unvested - December 31, 2016	7,090,465		$	32.43
Granted	3,762,717		35.14
Released	(2,086,837	)	33.63
Canceled	(1,188,887	)	33.34
Unvested - September 30, 2017	7,577,458		$	33.30

Schedule of Stock-Based Compensation Expense

The following table summarizes the effects of stock-based compensation expense related to stock-based awards in the condensed consolidated statements of operations during the periods presented (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Cost of revenue	$	993	$	764	$	2,931	$	1,572
Sales and marketing	7,305		7,191		21,434		20,376
Product development	11,976		9,284		34,428		25,727
General and administrative	5,035		5,321		16,214		14,721
Total stock-based compensation	$	25,309	$	22,560	$	75,007	$	62,396