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Acquisitions and Sale of Businesses - Narrative on acquisitions of subsidiaries (Details) - USD ($) $ in Millions |  |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jul. 03, 2023 | Dec. 06, 2021 | Dec. 31, 2022 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Business Acquisitions [Line Items] |  |  |  |  |  |
Cash paid at purchase |  |  |  | $ 234 | $ 10 | $ 123
Finite-lived intangible assets useful life |  | 10 years |  |  |  |
Crop Risk Services |  |  |  |  |  |
Business Acquisitions [Line Items] |  |  |  |  |  |
Cash paid at purchase | $ 234 |  |  |  |  |
Net tangible assets acquired, at fair value | 24 |  |  |  |  |
Acquisition costs incurred | 3 |  |  |  |  |
Goodwill acquired during period | 85 |  |  | $ 85 |  |
Goodwill deductible for tax purposes | 79 |  |  |  |  |
Crop Risk Services | Customer relationships |  |  |  |  |  |
Business Acquisitions [Line Items] |  |  |  |  |  |
Intangible assets acquired | 124 |  |  |  |  |
Finite-lived intangible assets useful life |  |  |  | 14 years |  |
Crop Risk Services | Crop Insurance Contract, Crop Year 2022 |  |  |  |  |  |
Business Acquisitions [Line Items] |  |  |  |  |  |
Gross written premiums | $ 1,200 |  |  |  |  |
Verikai, Inc. |  |  |  |  |  |
Business Acquisitions [Line Items] |  |  |  |  |  |
Cash paid at purchase |  | $ 120 |  |  |  |
Acquisition costs incurred |  | 1 |  |  |  |
Intangible assets acquired |  | 76 |  |  |  |
Goodwill acquired during period |  | 70 |  |  |  | $ 70
Total purchase price |  | $ 143 |  |  |  |
Insurance Agency |  |  |  |  |  |
Business Acquisitions [Line Items] |  |  |  |  |  |
Cash paid at purchase |  |  | $ 10 |  |  |
Total purchase price |  |  | $ 12 |  |  |

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479907/805-20-50-5 + Details
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- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 30 -Paragraph 8 -SubTopic 30 -Topic 805 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479637/805-30-30-8 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b) -SubTopic 30 -Topic 805 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479581/805-30-50-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 30 -Paragraph 7 -SubTopic 30 -Topic 805 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479637/805-30-30-7 + Details
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