Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Table Text Blocks

Summary of stock option activity

		Weighted-Average
	Shares		Exercise Price
Outstanding at December 31, 2019	5,795,710	$	58.82
Granted	1,296,203		58.40
Exercised	(208,510)		18.93
Canceled	(222,413)		77.27
Outstanding at June 30, 2020	6,660,990	$	59.37
Exercisable at June 30, 2020	3,136,170	$	46.60

Summary of restricted stock units activity

		Weighted-Average
		Grant Date
	Shares	Fair Value
Unvested shares at December 31, 2019	419,755	$	82.50
Granted	853,895		56.46
Vested	(76,606)		85.95
Forfeited	(45,633)		69.62
Unvested shares at June 30, 2020	1,151,411	$	63.47

Summary of stock-based compensation expense, allocation by type of awards and recognition in statements of operations

	Three Months Ended				Six Months Ended
		June 30,				June 30,
		2020		2019		2020		2019
Stock options	$	14,629	$	12,016	$	28,344	$	21,595
Restricted stock units		4,844		1,544		7,998		2,168
Employee stock purchase plan		202		106		359		198
Subtotal		19,675		13,666		36,701		23,961
Capitalized stock-based compensation costs		(147)		—		(314)		—
Stock-based compensation expense included in total cost and operating expenses	$	19,528	$	13,666	$	36,387	$	23,961

Stock-based compensation expense by classification within the unaudited condensed consolidated statements of operations and comprehensive loss is as follows (in thousands):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Research and development	$	8,709	$	7,503	$	16,507	$	13,293
Selling, general and administrative		10,819		6,163		19,880		10,668
Total		19,528		13,666		36,387		23,961