Investments - Commercial Mortgage Loans Segregated By Aging of Loans and Charge Offs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2024	Dec. 31, 2023
Charge-offs
2023	$ 0	$ 0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Commercial mortgage loans
Credit Quality Indicator Current Year [Abstract]
2024	35	213
2023	214	288
2022	288	1,256
2021	1,256	512
2020	513	0
Prior	257	259
Total	2,563	2,528
Credit Quality Indicator Prior Year [Abstract]
2023	35	213
2022	214	288
2021	288	1,256
2020	1,256	512
2019	513	0
Prior	257	259
Total	2,563	2,528
Loans under development, amortized cost	22	22
Loans under development, fair value	22	22
Charge-offs
Prior	0	3
Total	0	3
Commercial mortgage loans \| Current (less than 30 days past due)
Credit Quality Indicator Current Year [Abstract]
2024	35	213
2023	214	288
2022	288	1,256
2021	1,256	512
2020	513	0
Prior	257	259
Total	2,563	2,528
Credit Quality Indicator Prior Year [Abstract]
2023	35	213
2022	214	288
2021	288	1,256
2020	1,256	512
2019	513	0
Prior	257	259
Total	2,563	2,528
Commercial mortgage loans \| 30-89 days past due
Credit Quality Indicator Current Year [Abstract]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	0
Total	0	0
Credit Quality Indicator Prior Year [Abstract]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior	0	0
Total	0	0
Commercial mortgage loans \| 90 Days or more past due
Credit Quality Indicator Current Year [Abstract]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	0
Total	0	0
Credit Quality Indicator Prior Year [Abstract]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior	0	0
Total	$ 0	$ 0

Credit Quality Indicator Current Year

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Credit Quality Indicator Prior Year

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Financing Receivable, Excluding Loans In Process, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year

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Financing Receivable, Excluding Loans In Process, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year

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Financing Receivable, Excluding Loans In Process, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year

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Financing Receivable, Excluding Loans In Process, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year

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Financing Receivable, Excluding Loans In Process, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year

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Financing Receivable, Excluding Loans In Process, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year

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Loans Under Development, Amortized Cost

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- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

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Amortized cost excluding accrued interest, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes net investment in lease.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481598/310-20-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

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Amount, excluding accrued interest, of writeoff of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable originated in current fiscal year. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable originated two years before current fiscal year. Excludes net investment in lease.

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Amount, excluding accrued interest, of writeoff of financing receivable originated in fiscal year before current fiscal year. Excludes net investment in lease.

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