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Acquisitions and Dispositions of Businesses - Narrative (Details) - USD ($) shares in Millions, $ in Millions |  |  | 3 Months Ended | 6 Months Ended | 9 Months Ended | 101 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 01, 2025 | Apr. 25, 2024 | Sep. 30, 2025 | Jun. 30, 2025 | Sep. 30, 2024 | Jun. 30, 2025 | Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Oct. 30, 2025 | Sep. 03, 2025 | Dec. 31, 2024 | May 01, 2017
Business Combination [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Decrease of goodwill |  |  |  |  |  |  | $ 27 |  |  |  |  |  |
Gain on disposition of business |  |  | $ 1 |  | $ 76 |  | 1 | $ 333 |  |  |  |  |
Disposal group, including discontinued operation, assets, current |  |  | 1,274 |  |  |  | 1,274 |  | $ 1,274 |  |  | $ 1 |
Disposal group, including discontinued operation, liabilities, current |  |  | 166 |  |  |  | 166 |  | 166 |  |  | $ 0 |
Deferred consideration on divestiture |  |  |  |  | $ 2 |  | $ 108 | $ 84 | $ 192 |  |  |  |
Held-for-sale | NFP Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Disposal group, not discontinued operation, impairment loss |  |  | $ 0 |  |  |  |  |  |  |  |  |  |
Disposal group, including discontinued operation, assets, current |  |  |  |  |  |  |  |  |  |  | $ 1,300 |  |
Disposal group, including discontinued operation, liabilities, current |  |  |  |  |  |  |  |  |  |  | 166 |  |
Disposal group, including discontinued operation, intangible assets, current |  |  |  |  |  |  |  |  |  |  | 754 |  |
Disposal group, including discontinued operation, goodwill, current |  |  |  |  |  |  |  |  |  |  | $ 389 |  |
Held-for-sale | NFP Acquisition | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase price |  |  |  |  |  |  |  |  |  | $ 2,300 |  |  |
Disposed of by Sale | May 1, 2017 Divested Business |  |  |  |  |  |  |  |  |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase price |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,300
Deferred consideration |  |  |  |  |  |  |  |  |  |  |  |  | $ 500
Griffiths & Armour |  |  |  |  |  |  |  |  |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of capital acquired | 100.00% |  |  |  |  |  |  |  |  |  |  |  |
Total consideration | $ 418 |  |  |  |  |  |  |  |  |  |  |  |
NFP Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of capital acquired |  | 100.00% |  |  |  |  |  |  |  |  |  |  |
Total consideration |  | $ 9,100 |  |  |  | $ 9,129 |  |  |  |  |  |  |
Cash |  | $ 3,200 |  |  |  | $ 3,247 |  |  |  |  |  |  |
Number of shares issued for acquisition (up to) |  | 19 |  |  |  |  |  |  |  |  |  |  |
Equity interest issued or issuable, value |  | $ 5,900 |  |  |  |  |  |  |  |  |  |  |
Adjustments for cash and certain assumed liabilities |  | $ 3,900 |  |  |  |  |  |  |  |  |  |  |
Increase of intangible assets |  |  |  | $ 125 |  |  |  |  |  |  |  |  |
Decrease of deferred tax liabilities |  |  |  | 110 |  |  |  |  |  |  |  |  |
Decrease of other noncurrent assets |  |  |  | 61 |  |  |  |  |  |  |  |  |
Decrease of other current assets |  |  |  | 28 |  |  |  |  |  |  |  |  |
Decrease of goodwill |  |  |  | $ 115 |  |  |  |  |  |  |  |  |

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