Employee Equity-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

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

Stock Option Activity

The following table summarizes option activity under all plans during the three-month period ending March 31, 2017:

Stock Option Activity
	Number of Shares		Weighted Average Exercise Price per Share
Options outstanding December 31, 2016	6,857,124		7.72
Granted	817,437		24.36
Forfeited	(26,591	)	16.58
Exercised	(123,121	)	8.96
Expired	—		—
Options Outstanding March 31, 2017	7,524,849		9.48

Black-Scholes Assumptions for Options Granted

The table below summarizes the resulting weighted average inputs used to calculate the estimated fair value of options awarded during the periods shown below:

Black-Scholes Assumptions for Options Granted
	Three Months Ended
	March 31, 2017			March 31, 2016
Expected term (in years)	6.19			6.48
Volatility	79		%	87		%
Expected dividends	—			—
Risk free interest rates	2.07		%	1.61		%
Weighted average fair value	$	16.84		$	9.68

Stock Option Supplemental Information

The following table shows summary information for outstanding options, options that are exercisable (vested) and outstanding options that are either vested or expected to vest as of March 31, 2017:

Stock Option Supplemental Information
	Options Outstanding		Options Exercisable
Number of options	7,524,849		4,953,299
Weighted average remaining contractual term (in years)	6.74		5.79
Weighted average exercise price	$	9.48	$	5.41
Weighted average fair value	$	7.09	$	4.12
Aggregate intrinsic value (in thousands)	$	98,899	$	92,772

Restricted Stock Unit (RSU) Activity

The following table summarizes restricted stock unit activity during the three-month period ending March 31, 2017:

Restricted Stock Unit (RSU) Activity
	Number of Shares		Weighted Average Grant Date Fair Value per Share
RSUs Outstanding December 31, 2016	40,250		20.91
Granted	—		—
Forfeited	—		—
Vested/released	(16,100	)	20.91
RSUs outstanding March 31, 2017	24,150		20.91

Equity-Based Compensation Expenses

The expense recognized on the Company’s condensed consolidated statements of operations and comprehensive loss related to options is summarized below:

Equity-Based Compensation Expenses (in thousands)
	Three Months Ended
	March 31, 2017		March 31, 2016
Research and development	$	726	$	202
Sales, general and administrative	2,489		1,484
Equity-based compensation expense	$	3,215	$	1,686

As of March 31, 2017, $202,000 of equity-based compensation expense was a component of capitalized inventory.