Investments (Details) - Additional Information - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investments [Abstract]
Proceeds from sales of real estate investments	$ 10	$ 31	$ 0
Gains realized on sales of real estate investments	4	8
Realized losses included in net realized investment gains (losses) related to real estate impairments	12
Accumulated depreciation on real estate held for investment purposes	519	497
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2023	116
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2024	103
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2025	78
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2026	59
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2027	45
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2028 and thereafter	$ 63
Combined average days to maturity of short-term securities (in days)	41 days
Amortized cost of short-term securities (which approximates fair value)	$ 3,470	$ 3,836
Availability of financial information provided by hedge funds following the date of the reporting	1 month
Availability of financial information provided by private equity and real estate partnerships following the date of the reporting, maximum	3 months
Minimum percentage of equity interest that must be held by the Company in order for the investment in a VIE to be considered significant	20.00%

Number of months within which financial information provided by hedge funds is available following the reporting date.

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Maximum number of months before which financial information provided by private equity and real estate partnerships is available following the reporting date.

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Combined average maturity (in days) on short-term securities.

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The minimum percentage of equity interest that must be held by the Company in order for the investment in a VIE to be considered significant.

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The net gain (loss) resulting from sales and other disposals of real estate owned for investment purposes.

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The charge against earnings in the period to reduce the carrying amount of real property to fair value.

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Amount of lease payment to be received by lessor for operating lease in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of short-term investments classified as other.

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Cash received from the sale of real estate that is held for investment, that is, it is part of an investing activity during the period.

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The cumulative amount of depreciation for real estate property held for investment purposes.

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