Short-term Investments (Tables)

3 Months Ended

Mar. 31, 2020

Short Term Investments [Abstract]

Summary of Short-term Investments

The following is a summary of our short-term investments (in thousands):

	March 31, 2020
			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		Losses			Fair Value
U.S. treasury bills and government agency obligations	$	100,499	$	932	$	—		$	101,431
U.S. corporate debt securities		70,077		—		(139	)		69,938
Foreign corporate debt securities		25,578		—		(85	)		25,493
U.S. commercial paper		25,873		—		—			25,873
Foreign commercial paper		30,326		—		—			30,326
Total	$	252,353	$	932	$	(224	)	$	253,061

	December 31, 2019
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
	Cost		Gains		Losses		Fair Value
U.S. treasury bills and government agency obligations	$	140,567	$	59	$	—	$	140,626
U.S. corporate debt securities		80,159		11		—		80,170
Foreign corporate debt securities		23,188		15		—		23,203
U.S. commercial paper		32,801		—		—		32,801
Foreign commercial paper		42,274		—		—		42,274
Total	$	318,989	$	85	$	—	$	319,074