Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2021

Fair Value Measurements

Summary of financial assets and liabilities measured on recurring basis

	September 30, 2021								December 31, 2020
	Level I		Level II		Level III		Total		Level I		Level II		Level III		Total
	(in thousands)
Financial Assets:
Money market deposits	$	55,703	$	—	$	—	$	55,703	$	28,990	$	—	$	—	$	28,990
U.S. Treasury securities		787,875		—		—		787,875		597,744		—		—		597,744
Corporate bonds and notes		—		52,721		—		52,721		—		12,328		—		12,328
Municipal securities		—		88,000		—		88,000		—		78,534		—		78,534
Total financial assets	$	843,578	$	140,721	$	—	$	984,299	$	626,734	$	90,862	$	—	$	717,596