Common Stock and Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Summary of Stock Option and RSU Activity

A summary of our stock option and RSU activity for the year ended December 31, 2016 is as follows (in thousands, except per share information):

			Options Outstanding							RSUs Outstanding
	Shares Available for Grant		Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value		Outstanding RSUs		Weighted Average Grant Date Fair Value
							(In years)
Outstanding — January 1, 2016	4,323		10,778		$	11.94	7.96	$	156,262	6,417		$	19.54
Increase in authorized shares	5,716
Stock options granted	(1,413	)	1,413		23.72
RSUs granted	(4,216	)								4,216		21.05
Stock options exercised			(2,924	)	8.70
RSUs vested										(2,894	)	18.51
Unvested shares repurchased	38
Stock options forfeited or canceled	788		(788	)	17.37
RSUs forfeited or canceled	803									(803	)	20.18
Outstanding — December 31, 2016	6,039		8,479		$	14.52	7.49	$	66,449	6,936		$	20.81
Options vested and expected to vest as of December 31, 2016			8,001		$	14.24	7.43	$	64,639
Options vested and exercisable as of December 31, 2016			3,698		$	11.47	6.91	$	38,609

Assumptions Used to Estimate Fair Value of Stock Options Granted to Employees

The assumptions used to estimate the fair value of stock options granted to employees are as follows:

	Year Ended December 31,
	2016	2015	2014
Expected volatility	47% - 49%	49% - 54%	54% - 56%
Dividend rate	0%	0%	0%
Risk-free interest rate	1.1% - 2.0%	1.4% - 2.0%	1.75% - 2.02%
Expected term (in years)	6.02 - 6.08	6.02 - 6.08	6.02 - 6.50

Assumptions Used to Estimate Fair Value of ESPP Awards

The assumptions used to estimate the fair value of ESPP awards are as follows:

	Year Ended December 31, 2016	Year Ended December 31, 2015
Expected volatility	42% - 48%	37% - 43%
Dividend rate	0%	0%
Risk-free interest rate	0.38% - 0.90%	0.09% - 0.69%
Expected term (in years)	0.50 -1.50	0.50 -1.50