Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2021

Fair Value Measurements

Summary of financial assets and liabilities measured on recurring basis

	March 31, 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	$	24,619	$	—	$	—	$	24,619	$	28,990	$	—	$	—	$	28,990
U.S. Treasury securities		495,538		—		—		495,538		597,744		—		—		597,744
Corporate bonds and notes		—		16,248		—		16,248		—		12,328		—		12,328
Municipal securities		—		76,660		—		76,660		—		78,534		—		78,534
Total financial assets	$	520,157	$	92,908	$	—	$	613,065	$	626,734	$	90,862	$	—	$	717,596