5. INVESTMENT SECURITIES, AVAILABLE-FOR-SALE AND FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2023

Investments, All Other Investments [Abstract]

Schedule of Fair Value Hierarchy Assets and Liabilities

The valuation inputs hierarchy classification for assets measured at fair value on a recurring basis are summarized below as of March 31, 2023 and December 31, 2022 (in thousands). These tables do not include cash held in our money market savings accounts.

	Level 1		Level 2		Level 3		Total
As of March 31, 2023
Assets
Corporate debt securities	$	—	$	15,041	$	—	$	15,041
U.S. Treasury securities		—		29,503		—		29,503
	$	—	$	44,544	$	—	$	44,544

	Level 1		Level 2		Level 3		Total
As of December 31, 2022
Assets
Corporate debt securities	$	—	$	15,500	$	—	$	15,500
U.S. Treasury securities		—		46,673		—		46,673
	$	—	$	62,173	$	—	$	62,173

Schedule of Unrealized Gain or Loss on Short-term Investments

Our short-term investments are summarized below as of March 31, 2023 and December 31, 2022 (in thousands).

								Investment
	Cost/		Gross		Gross			Securities,
	Amortized		Unrealized		Unrealized			Available-
	Cost		Gains		Losses			For-Sale
As of March 31, 2023
Assets
Corporate debt securities	$	15,063	$	—	$	(22	)	$	15,041
U.S. Treasury securities		29,531		2		(30	)		29,503
	$	44,594	$	2	$	(52	)	$	44,544
								Investment
	Cost/		Gross		Gross			Securities,
	Amortized		Unrealized		Unrealized			Available-
	Cost		Gains		Losses			For-Sale
As of December 31, 2022
Assets
Corporate debt securities	$	15,538	$	—	$	(38	)	$	15,500
U.S. Treasury securities		46,762		2		(91	)		46,673
	$	62,300	$	2	$	(129	)	$	62,173

+Maturity Date of Available-for-sale Securities

The maturities of the investment securities available-for-sale as of March 31, 2023 and December 31, 2022 are shown below (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
As of March 31, 2023
Maturity date
Less than one year	$	44,594	$	2	$	(52	)	$	44,544
	$	44,594						$	44,544
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
As of December 31, 2022
Maturity date
Less than one year	$	62,300	$	2	$	(129	)	$	62,173
	$	62,300						$	62,173

Schedule of Unrealized Loss on Investment Securities

The following table summarizes investments that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for more than 12 months as of March 31, 2023 and December 31, 2022 (in thousands):    

	Less than Twelve Months					Twelve Months or Greater				Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
As of March 31, 2023
Corporate debt securities	$	11,591	$	(22	)	$	—	$	—	$	11,591	$	(22	)
U.S. Treasury securities		14,858		(30	)		—		—		14,858		(30	)
	$	26,449	$	(52	)	$	—	$	—	$	26,449	$	(52	)
	Less than Twelve Months					Twelve Months or Greater				Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
As of December 31, 2022
Corporate debt securities	$	12,295	$	(38	)	$	—	$	—	$	12,295	$	(38	)
U.S. Treasury securities		34,530		(91	)		—		—		34,530		(91	)
	$	46,825	$	(129	)	$	—	$	—	$	46,825	$	(129	)