Cash Equivalents and Marketable Securities

3 Months Ended

Mar. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Cash Equivalents and Marketable Securities

Cash Equivalents and Marketable Securities

At March 31, 2020, marketable securities consisted of the following (in thousands):

	Amortized Cost		Unrealized Gains		Unrealized Losses		Aggregate Fair Value
Money market funds	$	367,978	$	—	$	—	$	367,978
Commercial paper	2,961		—		—		2,961
U.S. treasury debt securities	20,888		283		—		21,171
U.S. corporate debt securities	78,532		49		(124)		78,457
	$	470,359	$	332	$	(124)	$	470,567
Included in cash and cash equivalents	$	367,978	$	—	$	—	$	367,978
Included in marketable securities	$	102,381	$	332	$	(124)	$	102,589

At December 31, 2019, marketable securities consisted of the following (in thousands):

	Amortized Cost		Unrealized Gains		Unrealized Losses		Aggregate Fair Value
Money market funds	$	360,471	$	—	$	—	$	360,471
U.S. treasury debt securities	10,342		8		(1)		10,349
U.S. corporate debt securities	95,706		164		(5)		95,865
	$	466,519	$	172	$	(6)	$	466,685
Included in cash and cash equivalents	$	360,471	$	—	$	—	$	360,471
Included in marketable securities	$	106,048	$	172	$	(6)	$	106,214

The following table presents gross unrealized losses and fair values for those marketable securities that were in an unrealized loss position as of March 31, 2020, aggregated by investment category and the length of time that individual securities have been in a continuous loss position (in thousands):

	As of March 31, 2020
	Less than 12 months				12 months or greater
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
U.S. corporate debt securities	$	48,338	$	(124)	$	—	$	—
Total	$	48,338	$	(124)	$	—	$	—

We do not believe the unrealized losses represent credit losses based on our evaluation of available evidence as of March 31, 2020, which includes an assessment of whether it is more likely than not we will be required to sell the investment before recovery of the investment's amortized cost basis.