Stock-Based Compensation Expense (Tables)

9 Months Ended

Sep. 30, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Stock-Based Compensation Expense

Stock-based compensation expense for restricted stock, restricted stock units, stock options and issuances of common stock pursuant to our employee stock purchase plan was classified in the accompanying consolidated statements of operations as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
	(in thousands)
Stock-based compensation expense:
Cost of revenue	$	166	$	102	$	445	$	203
Research and development		1,600		507		4,617		917
Sales and marketing		1,328		418		5,453		728
General and administrative		1,083		400		2,822		985

Total stock-based compensation expense	$	4,177	$	1,427	$	13,337	$	2,833

Summary of Restricted Stock and Restricted Stock Unit Activity

Restricted stock and restricted stock unit activity during the nine months ended September 30, 2016 was as follows:


	Restricted Stock			Weighted Average Grant Date Fair Value
Unvested balance as of December 31, 2015		1,149,257		$	19.34
Granted		800,791			13.12
Vested		(494,554	)		19.86
Forfeited		(101,880	)		14.27

Unvested balance as of September 30, 2016		1,353,614		$	15.85

Summary of Stock Option Activity

Stock option activity during the nine months ended September 30, 2016 was as follows:


	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2015		4,246,525		$	5.99
Granted		1,279,034			13.12
Exercised		(576,154	)		4.29			$	5,791
Forfeited/cancelled		(429,343	)		10.69

Outstanding as of September 30, 2016		4,520,062			7.89		7.4	$	44,403

Vested and exercisable as of September 30, 2016		2,725,099			5.35		6.5	$	33,624
Vested and expected to vest as of September 30, 2016		4,174,837			7.51		7.3	$	42,556