Financial Instruments

3 Months Ended

Mar. 31, 2020

Investments, All Other Investments [Abstract]

Financial InstrumentsThe fair value and amortized cost of cash equivalents and available-for-sale securities by major security type as of March 31, 2020 and as of December 31, 2019 are presented in the following tables:


	March 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Money market funds	$	113,143	$	—	$	—	$	113,143
Commercial paper	25,786		—		—		25,786
Corporate bonds	190,625		505		(276)		190,854
U.S. treasury securities	178,695		1,618		—		180,313
U.S. agency securities	28,986		207		(1)		29,192
Total cash equivalents and investments	$	537,235	$	2,330	$	(277)	$	539,288

Classified as:
Cash equivalents							$	122,141
Short-term investments							357,026
Long-term investments							60,121
Total cash equivalents and investments							$	539,288


	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Money market funds	$	122,900	$	—	$	—	$	122,900
Corporate bonds	204,144		871		(4)		205,011
U.S. treasury securities	181,340		557		(3)		181,894
U.S. agency securities	25,658		167		(1)		25,824
Certificates of deposit	1,000		—		—		1,000
Total cash equivalents and investments	$	535,042	$	1,595	$	(8)	$	536,629

Classified as:
Cash equivalents							$	122,900
Short-term investments							355,407
Long-term investments							58,322
Total cash equivalents and investments							$	536,629

As of March 31, 2020, the remaining contractual maturities of available-for-sale securities were less than 3 years. There have been no significant realized losses on available-for-sale securities for the period presented. As of March 31, 2020, unrealized losses on available-for-sale investments are not attributed to credit risk. The Company believes that it is more-likely-than-not that investments in an unrealized loss position will be held until maturity or the recovery of the cost basis of the investment. The Company believes that an allowance for credit losses is unnecessary because the unrealized losses on certain of the Company’s marketable securities are due to market factors. To date, the Company has not recorded any impairment charges on marketable securities.