Stock-Based Compensation (Tables)
 9 Months Ended
Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Summary of Option Activity
A summary of the option activity during the nine months ended September 30, 2016 is presented below:    
 
 
Options Outstanding
 
 
Shares
 
Weighted Average Exercise Price Per Share
 
Weighted Average Remaining Contractual Term
 
Aggregate Intrinsic Value
 
 
 
 
 
 
(in years)
 
(in thousands)
Balances at December 31, 2015
 
5,953,771

 
$
8.92

 
 
 
 
Options granted
 
75,000

 
54.87

 
 
 
 
Options exercised
 
(1,186,096
)
 
8.19

 
 
 
 
Options canceled
 
(287
)
 
57.87

 
 
 
 
Options forfeited
 
(90,862
)
 
23.83

 
 
 
 
Balances at September 30, 2016
 
4,751,526

 
$
9.53

 
5.41
 
$
217,321

Vested and expected to vest at September 30, 2016
 
4,751,489

 
$
9.53

 
5.41
 
$
217,320

Exercisable at September 30, 2016
 
4,391,379

 
$
8.38

 
5.27
 
$
205,899
Summary of RSU Activity
A summary of the RSU activity during the nine months ended September 30, 2016 is presented below:
 
 
Number of Shares Underlying Outstanding RSUs
 
Weighted-Average Grant-Date Fair Value per RSU
Non-Vested outstanding at December 31, 2015
 
5,406,077

 
$
93.61

RSUs granted
 
4,207,257

 
44.54

RSUs vested
 
(1,421,083
)
 
93.42

RSUs forfeited
 
(496,327
)
 
72.76

Non-Vested outstanding at September 30, 2016
 
7,695,924

 
$
68.00
Summary of Shares Available for Grant
The summary of shares available for issuance of equity based awards (including stock options and RSUs) during the nine months ended September 30, 2016 is as follows:
 
 
Shares Available for Grant
 
 
2013 Plan
 
2013 ESPP
Balances at December 31, 2015
 
6,361,749

 
3,320,668

Authorized
 
3,660,223

 
732,044

Granted
 
(4,282,257
)
 
(262,668
)
Canceled
 
287

 
—

Forfeited
 
587,189

 
—

Balances at September 30, 2016
 
6,327,191

 
3,790,044