Investments (Tables)

12 Months Ended

Dec. 31, 2020

Schedule Of Investments [Abstract]

Summary of Fair Value of Available-for-Sale Investments by Type of Security

The fair value of available-for-sale investments by type of security was as follows:

	December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Investments:
U.S treasury bills	$	29,997	$	21	$	—	$	30,018
U.S agency securities		20,996	5			—		21,001
Total investments with a maturity of one year or less		50,993		26		—		51,019
U.S treasury bills		3,008		—		—		3,008
U.S agency securities		176,350	38			—		176,388
Total investments with a maturity of one to two years		179,358		38		—		179,396
Total investments	$	230,351	$	64	$	—	$	230,415

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Investments:
U.S treasury bills	$	232,336	$	268	$	—	$	232,604
U.S agency securities		81,201		57		—		81,258
Total investments with a maturity of one year or less	$	313,537	$	325	$	—	$	313,862