Cash and Investments in Marketable Securities

12 Months Ended

Dec. 31, 2022

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents, and Marketable Securities

Cash and Investments in Marketable Securities    Cash and investments in marketable securities, including cash equivalents, are as follows (in thousands):

	Estimated Fair Value at
	December 31, 2022		December 31, 2021
Cash and cash equivalents	$	88,227	$	25,218
Short-term investments	416,750		708,737
Long-term investments	—		64,828
Total cash and investments in marketable securities	$	504,977	$	798,783

    We invest in liquid, high quality debt securities. Our investments in debt securities are subject to interest rate risk. To minimize the exposure due to an adverse shift in interest rates, we invest in securities with maturities of two years or less and maintain a weighted average maturity of one year or less. All of our long-term investments as of December 31, 2021 had maturities between one and two years.

    During the year ended December 31, 2022 we sold no available-for-sale securities. During the years ended December 31, 2021 and 2020, we sold available-for-sale securities totaling $11.5 million and $41.7 million, respectively. Gross realized gains and losses on those sales were not significant.

We report our accrued interest receivable, which totaled $0.7 million and $1.4 million at December 31, 2022 and December 31, 2021, respectively, in other current assets on our Consolidated Balance Sheets.

    Our portfolio of cash and investments in marketable securities includes (in thousands):

	Fair Value Hierarchy Level	December 31, 2022								December 31, 2021
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Fair Value
Corporate notes and bonds	2	$	84,377	$	—	$	(855)	$	83,522	$	278,121
Corporate commercial paper	2	345,125		25		(946)		344,204		478,629
Obligations of U.S. government agencies	2	—		—		—		—		5,875
Available-for-sale investments		429,502		25		(1,801)		427,726		762,625
Money market funds	1							47,054		23,968
Certificates of deposit	2							21,399		10,940
Cash	N/A							8,798		1,250
Total cash and investments in marketable securities								$	504,977	$	798,783

    At December 31, 2021, our gross unrealized losses totaled $0.7 million. Our gross unrealized gains were not significant. As of December 31, 2022 and 2021, we assessed our marketable securities with unrealized losses and concluded that the losses were not attributable to credit. Accordingly, we have not recorded an allowance for credit losses for these securities.

At both December 31, 2022 and 2021, we had letter of credit arrangements in favor of our landlords and certain vendors totaling $7.5 million and $8.1 million, respectively. These letters of credit are secured by investments of similar amounts.