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Acquisition of Businesses - Allocation of purchase price of subsidiary (Details) - USD ($) $ in Millions |  | 9 Months Ended
--- | --- | ---
Jul. 03, 2023 | Sep. 30, 2023 | Sep. 30, 2022
Business Acquisition [Line Items] |  |  |
Payments to acquire subsidiaries |  | $ 234 | $ 10
Crop Risk Services |  |  |
Business Acquisition [Line Items] |  |  |
Payments to acquire subsidiaries | $ 234 |  |
Tangible assets acquired: |  |  |
Cash and cash equivalents | 26 |  |
Agents’ balances and premiums receivable | 164 |  |
Other assets | 3 |  |
Total tangible assets acquired | 193 |  |
Liabilities acquired: |  |  |
Other liabilities | 169 |  |
Total liabilities acquired | 169 |  |
Net tangible assets acquired, at fair value | 24 |  |
Excess purchase price over net tangible assets acquired | 210 |  |
Deferred tax asset acquired | 1 |  |
Goodwill recorded | 85 |  |
Crop Risk Services | Customer relationships |  |  |
Liabilities acquired: |  |  |
Intangible assets acquired | $ 124 |  |

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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479907/805-20-50-1 + Details
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- Definition Amount of deferred tax asset attributable to deductible temporary differences and carryforwards acquired at the acquisition date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479907/805-20-50-1 + Details
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- Definition Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479303/805-10-55-37 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479907/805-20-50-1 + Details
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