Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 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	1,087,783		57.21
Exercised	(127,220)		12.67
Canceled	(112,822)		78.82
Outstanding at March 31, 2020	6,643,451	$	59.10
Exercisable at March 31, 2020	2,863,027	$	43.21

Summary of restricted stock units activity

		Weighted-Average
		Grant Date
	Shares	Fair Value
Unvested shares at December 31, 2019	419,755	$	82.50
Granted	751,946		55.33
Vested	(58,946)		85.29
Forfeited	(14,919)		82.07
Unvested shares at March 31, 2020	1,097,836	$	63.75

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

	Three Months Ended
		March 31,
		2020		2019
Stock options	$	13,716	$	9,579
Restricted stock units		3,153		624
Employee stock purchase plan		157		92
Subtotal		17,026		10,295
Capitalized stock-based compensation costs		(167)		—
Stock-based compensation expense included in total cost and operating expenses	$	16,859	$	10,295

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
	March 31,
	2020		2019
Research and development	$	7,798	$	5,790
Selling, general and administrative		9,061		4,505
Total		16,859		10,295