Equity Incentive Plans (Tables)

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity during the nine months ended September 30, 2019:

	Shares Subject to Options Outstanding					Weighted- Average
				Weighted-		Remaining
				Average Exercise		Contractual Life		Aggregate
	Shares			Price		(Years)		Intrinsic Value
								(in thousands)
Outstanding as of December 31, 2018		5,107,329		$	7.51		9.7	$	16,343
Options granted		3,441,901		$	20.79
Option exercised		(173,712	)	$	3.04
Options forfeited/cancelled		(275,657	)	$	12.30
Outstanding as of September 30, 2019		8,099,861		$	13.09		9.2	$	44,015
Options vested and exercisable as of September 30,    2019		644,722		$	3.88		8.7	$	8,323

Summary of Restricted Stock Activity

The summary of the Company’s restricted stock activity is as follows:

	Number of			Weighted-
	Restricted			Average
	Stock Units			Grant Date
	Outstanding			Fair Value
Nonvested at December 31, 2018		7,482,032		$	4.01
Granted		—			—
Vested		(2,428,863	)	$	4.11
Forfeited		—			—
Nonvested at September 30, 2019		5,053,169		$	3.96

Stock-Based Compensation Expense Reported in Condensed Consolidated Statements of Operations

Stock-based compensation expense has been reported in the Company’s condensed consolidated statements of operations as follows (in thousands):

	Three months ended				Nine months ended
	September 30,				September 30,
	2019		2018		2019		2018
Research and development	$	2,727	$	144	$	6,483	$	200
General and administrative		3,001		18,025		7,474		19,948
Total stock-based compensation	$	5,728	$	18,169	$	13,957	$	20,148