Investments

9 Months Ended

Sep. 30, 2022

Investments

Investments

16. Investments

The amortized cost, gross unrealized gains and losses, fair value of those investments classified as available-for-sale, and allowance for credit losses at September 30, 2022 are summarized as follows (in thousands):

		September 30, 2022
	Amortized		Gross		Gross		Fair		Allowance for
	Cost		Unrealized Gains		Unrealized Losses		Value		Credit Losses
Corporate bonds	$	220,537	$	—	$	(9,004)	$	211,533		—
U.S. Treasuries		624,972		133		(17,198)		607,907		—
Total	$	845,509	$	133	$	(26,202)	$	819,440	$	—

The amortized cost, gross unrealized gains and losses, fair value of those investments classified as available-for-sale, and allowance for credit losses at December 31, 2021 are summarized as follows (in thousands):

		December 31, 2021
	Amortized		Gross		Gross		Fair		Allowance for
	Cost		Unrealized Gains		Unrealized Losses		Value		Credit Losses
Corporate bonds	$	228,614	$	—	$	(2,232)	$	226,382		—
U.S. Treasuries		1,014,319		20		(456)		1,013,883		—
Total	$	1,242,933	$	20	$	(2,688)	$	1,240,265	$	—

The following table summarizes the fair value and gross unrealized losses on securities classified as available-for-sale, and length of time that the individual securities have been in a continuous loss positon as of September 30, 2022 (in thousands):

	September 30, 2022
	Less than 12 months				12 months or greater				Total
	Fair Value of				Fair Value of				Fair Value of
	Investments with		Gross Unrealized		Investments with		Gross Unrealized		Investments with		Gross Unrealized
	Unrealized Losses		Losses		Unrealized Losses		Losses		Unrealized Losses		Losses
Corporate bonds	$	433,615	$	(4,385)	$	385,825	$	(21,818)	$	819,440	$	(26,202)
Total available-for-sale securities	$	433,615	$	(4,385)	$	385,825	$	(21,818)	$	819,440	$	(26,202)

We regulary review available-for-sale securities for declines in fair values that we determine to be credit related. In order to determine whether an allowance for credit losses was required, we considered factors such as whether amounts related to securities have become uncollectible, whether we intend to sell a security, and whether it is more likely than not that we will be required to sell a security prior to recovery. The Company also reviewed the declines in market value related to our available-for-sale securities and determined that these declines were due to fluctuations in interest rates. As of September 30, 2022, the Company did not have an allowance for credit losses related to available-for-sale securities.

The cost, gross unrealized gains and losses, and fair value of those investments classified as equity securities at September 30, 2022 are summarized as follows (in thousands):

	September 30, 2022
			Gross		Gross		Fair
		Cost	Unrealized Gains		Unrealized Losses		Value
Fixed income mutual funds	$	70,247	$	—	$	(2,854)	$	67,393
Exchange traded mutual funds		76,000		—		(13,272)		62,728
Total	$	146,247	$	—	$	(16,126)	$	130,121

The cost, gross unrealized gains and losses, and fair value of those investments classified as equity securities at December 31, 2021 are summarized as follows (in thousands):

	December 31, 2021
			Gross		Gross		Fair
		Cost	Unrealized Gains		Unrealized Losses		Value
Fixed income mutual funds	$	70,247	$	—	$	(574)	$	69,673
Exchange traded mutual funds		71,010		7,312		—		78,322
Total	$	141,257	$	7,312	$	(574)	$	147,995

A summary of the amortized cost and fair value of investments classified as available-for-sale, by contractual maturity, as of September 30, 2022 and December 31, 2021 was as follows (in thousands):

	September 30, 2022				December 31, 2021
		Amortized	Fair			Amortized	Fair
Maturity:		Cost	Value			Cost	Value
Less than 12 months	$	437,867	$	433,615	$	670,584	$	670,306
12 months or greater		407,642		385,825		572,349		569,959
Total	$	845,509	$	819,440	$	1,242,933	$	1,240,265

Accrued interest income was $3.0 million and $3.7 million at September 30, 2022 and December 31, 2021, respectively, and included within the balance for prepaid expenses and other current assets in the unaudited interim condensed consolidated balance sheets.