The following is a summary of available-for-sale marketable securities, excluding those securities classified within cash and cash equivalents, on the condensed consolidated balance sheets (in thousands):

	March 31, 2020
	Amortized Cost		Unrealized Gain		Unrealized Losses			Fair Value
Commercial debt securities	$	321,534	$	60	$	(2,096	)	$	319,498
Certificates of deposit		39,865		54		—			39,919
U.S. government agencies		14,914		58		—			14,972
U.S. government treasury securities		106,033		1,023		—			107,056
Commercial paper		118,908		31		—			118,939
Marketable securities	$	601,254	$	1,226	$	(2,096	)	$	600,384

	December 31, 2019
	Amortized Cost		Unrealized Gain		Unrealized Losses			Fair Value
Commercial debt securities	$	80,376	$	46	$	(5	)	$	80,417
U.S. government treasury securities		72,467		10		(4	)		72,473
Commercial paper		23,784		—		—			23,784
Marketable securities	$	176,627	$	56	$	(9	)	$	176,674

As of March 31, 2020, the fair values of available-for-sale marketable securities, by remaining contractual maturity, were as follows (in thousands):

Due within one year	$	478,459
Due in one year through five years		121,925
Total	$	600,384

The Company does not believe that any unrealized losses are attributable to credit-related factors based on its evaluation of available evidence. To determine whether a decline in value is related to credit loss, the Company evaluates, among other factors: the extent to which the fair value is less than the amortized cost basis, changes to the rating of the security by a rating agency and any adverse conditions specifically related to an issuer of a security or its industry. No tax benefits on unrealized losses have been reflected in the condensed consolidated statement of comprehensive income (loss) due to the Company’s full valuation allowance as of March 31, 2020 and December 31, 2019.