Investments - Payables for Collateral on Investments (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2025	Dec. 31, 2024
Carrying Value
Collateral payable for derivative investments	$ 8,743	$ 7,069
Securities pledged under securities lending agreements	172	157
Securities pledged under repurchase agreements	210	0
Investments pledged for FHLBI	2,015	2,650
Total payables for collateral on investments	11,140	9,876
Fair Value
Collateral payable for derivative investments	8,743	7,069
Securities pledged under securities lending agreements	165	151
Securities pledged under repurchase agreements	224	0
Investments pledged for FHLBI	2,758	3,657
Total payables for collateral on investments	$ 11,890	$ 10,877
Percentage of the fair value of domestic securities obtained as collateral under securities lending agreements.	102.00%	105.00%
Minimum
Fair Value
Percentage of the fair value of securities obtained as collateral under reverse repurchase agreements.	80.00%
Percentage of the fair value of FHLBI securities obtained as collateral under securities pledged for FHLBI for AFS Securities	105.00%
Percentage of the fair value of FHLBI securities obtained as collateral under securities pledged for FHLBI for mortgage loan	155.00%
Maximum
Fair Value
Percentage of the fair value of securities obtained as collateral under reverse repurchase agreements.	95.00%
Percentage of the fair value of FHLBI securities obtained as collateral under securities pledged for FHLBI for AFS Securities	115.00%
Percentage of the fair value of FHLBI securities obtained as collateral under securities pledged for FHLBI for mortgage loan	175.00%

Carrying Value Of Payables For Collateral On Investments [Abstract]

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- Definition

This item represents the percentage of the fair value of AFS securities obtained as collateral pledged.

+ References

No definition available.

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- Definition

This item represents the percentage of the fair value of Mortgage loans obtained as collateral pledged.

+ References

No definition available.

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- Definition

This item represents the percentage of the fair value of securities obtained as collateral under reverse repurchase agreements

+ References

No definition available.

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- Definition

This item represents the percentage of the fair value of domestic securities obtained as collateral under securities lending agreements

+ References

No definition available.

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- Definition

When entering into a derivative transaction, the amount of cash received as collateral from a counterparty.

+ References

No definition available.

+ Details

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- Definition

The fair value of cash received as collateral from a counterparty.

+ References

No definition available.

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- Definition

Fair Value Of Related Investments Or Collateral [Abstract]

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No definition available.

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- Definition

The amount of cash received as security in return for loaning securities to Federal Home Loan Bank of Indianapolis.

+ References

No definition available.

+ Details

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- Definition

The fair value of investments loaned to Federal Home Loan Bank of Indianapolis as of the balance sheet date.

+ References

No definition available.

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- Definition

Securities Pledged Under Repurchase Agreements Carrying Value

+ References

No definition available.

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- Definition

Securities Pledged Under Repurchase Agreements Fair Value

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No definition available.

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- Definition

The fair value of investments loaned to another party under securities lending agreements as of the balance sheet date.

+ References

No definition available.

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- Definition

The total fair value of investments related to payables for collateral on investments as of the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

Amount of obligation to return cash received as collateral for security loaned to another party.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04(11))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479170/946-210-S99-1

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- Definition

Amount, before effects of master netting arrangements, of financial assets loaned to entities in exchange for collateral. Includes liabilities not subject to a master netting arrangement and financial assets transferred other than securities that qualify as secured borrowings.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481395/860-30-55-4

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-Topic 860
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