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

6 Months Ended

Jun. 30, 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 June 30, 2023 and December 31, 2022 (in thousands). These tables do not include cash held in our money market savings accounts.

As of June 30, 2023	Level 1		Level 2		Level 3		Total
Assets
Corporate debt securities	$	—	$	8,629	$	—	$	8,629
U.S. Treasury securities		—		22,936		—		22,936
	$	—	$	31,565	$	—	$	31,565

As of December 31, 2022	Level 1		Level 2		Level 3		Total
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 June 30, 2023 and December 31, 2022 (in thousands).

								Investment
	Cost/		Gross		Gross			Securities,
	Amortized		Unrealized		Unrealized			Available-
	Cost		Gains		Losses			For-Sale
As of June 30, 2023
Assets
Corporate debt securities	$	8,645	$	—	$	(16	)	$	8,629
U.S. Treasury securities		22,952		1		(17	)		22,936
	$	31,597	$	1	$	(33	)	$	31,565

								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 June 30, 2023 and December 31, 2022 are shown below (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		Losses			Fair Value
As of June 30, 2023
Maturity date
Less than one year	$	31,597	$	1	$	(33	)	$	31,565
	$	31,597						$	31,565

	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 June 30, 2023 and December 31, 2022 (in thousands):

	Less than Twelve Months					Twelve Months or Greater				Total
			Gross					Gross				Gross
	Fair		Unrealized			Fair		Unrealized		Fair		Unrealized
	Value		Losses			Value		Losses		Value		Losses
As of June 30, 2023
Corporate debt securities	$	6,440	$	(16	)	$	—	$	—	$	6,440	$	(16	)
U.S. Treasury securities		17,258		(17	)		—		—		17,258		(17	)
	$	23,698	$	(33	)	$	—	$	—	$	23,698	$	(33	)

	Less than Twelve Months					Twelve Months or Greater				Total
			Gross					Gross				Gross
	Fair		Unrealized			Fair		Unrealized		Fair		Unrealized
	Value		Losses			Value		Losses		Value		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	)