STOCK-BASED COMPENSATION

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

11. STOCK-BASED COMPENSATION

The following table summarizes the Company’s stock awards granted for each of the periods indicated:

	For the Three Months Ended June 30,								For the Six Months Ended June 30,
	2020				2019				2020				2019
	Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value
Stock options		73,494	$	73.16		155,265	$	67.80		1,158,824	$	57.84		1,145,499	$	75.27
Restricted stock units		44,527	$	143.84		81,000	$	121.34		543,437	$	116.70		405,630	$	138.79

Stock-based Compensation Expense

For the three months ended June 30, 2020 and 2019, total stock-based compensation expense was $27.6 million and $19.8 million, respectively. For the six months ended June 30, 2020 and 2019, total stock-based compensation expense was $51.6 million and $35.9 million, respectively. The following table summarizes stock-based compensation expense by function included within the unaudited condensed consolidated statements of operations and comprehensive loss:

		For the Three Months Ended June 30,				For the Six Months Ended June 30,
		2020		2019		2020		2019
	(in thousands)
Research and development		$	11,140	$	6,923	$	20,389	$	12,010
Selling, general and administrative			16,476		12,839		31,251		23,891
Total stock-based compensation expense		$	27,616	$	19,762	$	51,640	$	35,901

The following table summarizes stock-based compensation expense by grant type included within the unaudited condensed consolidated statements of operations and comprehensive loss:

		For the Three Months Ended June 30,				For the Six Months Ended June 30,
		2020		2019		2020		2019
	(in thousands)
Stock options		$	17,848	$	13,777	$	33,203	$	25,234
Restricted stock awards/units			8,352		5,184		15,097		9,100
Employee stock purchase plan			1,416		801		3,340		1,567
Total stock-based compensation expense		$	27,616	$	19,762	$	51,640	$	35,901