Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2021

Fair Value Measurements

Summary of financial assets and liabilities measured on recurring basis

	June 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	$	5,509	$	—	$	—	$	5,509	$	28,990	$	—	$	—	$	28,990
U.S. Treasury securities		434,639		—		—		434,639		597,744		—		—		597,744
Corporate bonds and notes		—		14,248		—		14,248		—		12,328		—		12,328
Municipal securities		—		68,545		—		68,545		—		78,534		—		78,534
Total financial assets	$	440,148	$	82,793	$	—	$	522,941	$	626,734	$	90,862	$	—	$	717,596