Investments (Tables)

12 Months Ended

Dec. 31, 2021

Investments

Schedule of gross unrealized gains and losses, and the amortized cost, allowance for credit losses, and fair value of those investments classified as available-for-sale

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	$	—

Schedule of investments classified as equity securities

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

Schedule of the amortized cost and fair value of investments classified as available-for-sale, by contractual maturity

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

	December 31, 2021
		Amortized	Fair
Maturity:		Cost	Value
Within one year	$	670,584	$	670,306
After one through five years		572,349		569,959
Total	$	1,242,933	$	1,240,265