Investments (Tables)

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments

The following tables summarize our current investments as of the dates indicated:

	September 30, 2023
	Amortized Cost		Gross Unrealized				Estimated Fair Value
			Gains		Losses
	(In millions)
Corporate debt securities	$	2,739	$	1	$	121	$	2,619
Mortgage-backed securities	955		—		67		888
Asset-backed securities	378		—		17		361
Municipal securities	159		—		10		149
U.S. Treasury notes	51		—		—		51
Other	46		—		3		43
Total	$	4,328	$	1	$	218	$	4,111

	December 31, 2022
	Amortized Cost		Gross Unrealized				Estimated Fair Value
			Gains		Losses
	(In millions)
Corporate debt securities	$	2,303	$	2	$	121	$	2,184
Mortgage-backed securities	787		—		56		731
Asset-backed securities	308		—		20		288
Municipal securities	160		—		11		149
U.S. Treasury notes	106		—		1		105
Other	45		—		3		42
Total	$	3,709	$	2	$	212	$	3,499

Schedule of Contractual Maturities of Investments

The contractual maturities of our current investments as of September 30, 2023 are summarized below:

	Amortized Cost		Estimated Fair Value
	(In millions)
Due in one year or less	$	474	$	464
Due after one year through five years	2,447		2,334
Due after five years through ten years	440		424
Due after ten years	967		889
Total	$	4,328	$	4,111

Schedule of Available-for-Sale Investments

The following table segregates those available-for-sale investments that have been in a continuous loss position for less than 12 months, and those that have been in a continuous loss position for 12 months or more as of September 30, 2023:

	In a Continuous Loss Position for Less than 12 Months					In a Continuous Loss Position for 12 Months or More
	Estimated Fair Value		Unrealized Losses		Total Number of Positions	Estimated Fair Value		Unrealized Losses		Total Number of Positions
	(Dollars in millions)
Corporate debt securities	$	942	$	23	549	$	1,559	$	98	785
Mortgage-backed securities	272		10		219	567		57		297
Asset-backed securities	136		1		96	206		16		100
Municipal securities	—		—		—	121		10		123
Other	13		1		16	17		2		16
Total	$	1,363	$	35	880	$	2,470	$	183	1,321

The following table segregates those available-for-sale investments that have been in a continuous loss position for less than 12 months, and those that have been in a continuous loss position for 12 months or more as of December 31, 2022:

	In a Continuous Loss Position for Less than 12 Months					In a Continuous Loss Position for 12 Months or More
	Estimated Fair Value		Unrealized Losses		Total Number of Positions	Estimated Fair Value		Unrealized Losses		Total Number of Positions
	(Dollars in millions)
Corporate debt securities	$	1,124	$	45	683	$	887	$	76	371
Mortgage-backed securities	395		20		220	319		36		131
Asset-backed securities	161		6		108	118		14		59
Municipal securities	75		4		83	57		7		57
U.S. Treasury notes	88		1		6	—		—		—
Other	15		1		16	17		2		6
Total	$	1,858	$	77	1,116	$	1,398	$	135	624