Investments - Summary of Debt Securities with a Decline in Fair Value (Details) $ in Millions	Mar. 31, 2023 USD ($) position	Dec. 31, 2022 USD ($) position
Total
Fair Value	$ 7,433	$ 7,901
Total Amortized Cost	8,321	8,960
Unrealized Depreciation	$ (888)	$ (1,059)
Number of Issues \| position	3,760	3,777
Investment grade \| Debt securities
One year or less
Fair Value	$ 3,176	$ 5,533
Amortized Cost	3,362	6,127
Unrealized Depreciation	$ (186)	$ (594)
Number of Issues \| position	1,019	1,659
More than one year
Fair Value	$ 3,222	$ 1,151
Amortized Cost	3,808	1,487
Unrealized Depreciation	$ (586)	$ (336)
Number of Issues \| position	1,035	462
Below investment grade \| Debt securities
One year or less
Fair Value	$ 353	$ 887
Amortized Cost	371	964
Unrealized Depreciation	$ (18)	$ (77)
Number of Issues \| position	936	1,287
More than one year
Fair Value	$ 682	$ 330
Amortized Cost	780	382
Unrealized Depreciation	$ (98)	$ (52)
Number of Issues \| position	770	369

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months Or Longer

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