Available-for-Sale Securities and Fair Value Measurements

3 Months Ended

Mar. 31, 2022

Available For Sale Securities And Fair Value Measurements [Abstract]

Available-for-Sale Securities and Fair Value Measurements

Available-for-Sale Securities and Fair Value Measurements

The available-for-sale securities in our Condensed Consolidated Balance Sheets are as follows:

	March 31, 2022		December 31, 2021
	(in thousands)
Cash equivalents	$	24,266	$	45,088
Short-term marketable securities	283,665		145,918
Long-term marketable securities	22,566		112,277
Total marketable securities	$	330,497	$	303,283

The following table presents our available-for-sale securities grouped by asset type:

	Fair Value Hierarchy Level	March 31, 2022								December 31, 2021
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
		(in thousands)
Corporate bonds	Level 2	$	147,177	$	4	$	(1,023)	$	146,158	$	125,370	$	3	$	(276)	$	125,097
Commercial paper	Level 2	56,751		—		—		56,751		30,963		—		—		30,963
Asset-backed securities	Level 2	29,372		—		(110)		29,262		57,801		—		(67)		57,734
U.S. Treasury securities	Level 1	74,363		—		(303)		74,060		44,473		—		(72)		44,401
Money market funds	Level 1	24,266		—		—		24,266		45,088		—		—		45,088
Total marketable securities		$	331,929	$	4	$	(1,436)	$	330,497	$	303,695	$	3	$	(415)	$	303,283

We estimate the fair value of marketable securities classified as Level 1 using quoted market prices for these or identical investments obtained from a commercial pricing service. We estimate the fair value of marketable securities classified as Level 2 using inputs that may include benchmark yields, reported trades, broker/dealer quotes and issuer spreads.

We periodically review our debt securities to determine if any of our investments is impaired due to credit-related or other issues. If the fair value of our investment in any debt security is less than our amortized cost basis, we determine whether an allowance for credit losses is appropriate by assessing quantitative and subjective factors including, but not limited to, the nature of security, changes in credit ratings, analyst reports concerning the security’s issuer and industry, interest rate fluctuations and general market conditions.

As of March 31, 2022 and December 31, 2021, unrealized losses on our available-for-sale debt securities were $1.4 million and $0.4 million, respectively.

All of our investments, including those with unrealized losses, are not impaired. Unrealized losses on our investments are due to interest rate fluctuations. We do not intend to sell investments that currently have unrealized losses and it is highly unlikely that we will sell any investment before recovery of its amortized cost basis, which may be at maturity. Accordingly, we have not recorded an allowance for credit losses associated with these investments.

We classified accrued interest on our marketable securities of $1.0 million and $1.4 million as of March 31, 2022 and December 31, 2021, respectively, as prepaid and other current assets on our condensed consolidated balance sheets.

As of March 31, 2022, all our marketable securities had original maturities of less than two years. The weighted-average maturity of our holdings was seven months. As of March 31, 2022, our long-term marketable securities had remaining maturities ranging from 12 to 24 months. None of our marketable securities changed from one fair value hierarchy to another during the three months ended March 31, 2022