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Acquisitions and Dispositions of Businesses - Narrative (Details) shares in Millions |  |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Apr. 25, 2024 USD ($) employee shares | Mar. 01, 2024 USD ($) | Jun. 30, 2024 USD ($) | Dec. 31, 2024 USD ($) acquisition | Dec. 31, 2023 USD ($) acquisition | Dec. 31, 2022 USD ($)
Business Acquisition [Line Items] |  |  |  |  |  |
Number of business acquired under business combination | acquisition |  |  |  | 22 | 3 |
Total consideration |  |  |  | $ 9,600,000,000 | $ 50,000,000 |
Issuance of debt |  | $ 6,000,000,000 |  |  |  |
Proceeds from long-term lines of credit | $ 2,000,000,000 |  |  |  |  |
Goodwill |  |  |  | 15,234,000,000 | $ 8,414,000,000 | $ 8,292,000,000
Extinguishment of debt |  |  | $ 6,000,000 | 6,000,000 |  |
2024 Acquisition |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Total consideration |  |  |  | $ 9,629,000,000 |  |
Weighted average useful life |  |  |  | 19 years |  |
Acquisition related costs |  |  |  | $ 96,000,000 |  |
Revenue |  |  |  | 1,700,000,000 |  |
Cash |  |  |  | 3,714,000,000 |  |
Goodwill |  |  |  | $ 7,125,000,000 |  |
2024 Acquisition | Contract-Based Intangible Assets |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Weighted average useful life |  |  |  | 20 years |  |
2024 Acquisition | Tradenames |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Weighted average useful life |  |  |  | 10 years |  |
2024 Acquisition | Technology And Other Assets |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Weighted average useful life |  |  |  | 6 years |  |
Other Acquisitions |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Total consideration |  |  |  | $ 500,000,000 |  |
Cash |  |  |  | 467,000,000 |  |
Goodwill |  |  |  | 258,000,000 |  |
NFP Acquisition |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Total consideration | $ 9,100,000,000 |  |  | $ 9,129,000,000 |  |
Weighted average useful life |  |  |  | 19 years |  |
Acquisition related costs |  |  |  | $ 90,000,000 |  |
Revenue |  |  |  | 1,707,000,000 |  |
Percentage of capital acquired | 100.00% |  |  |  |  |
Cash | $ 3,200,000,000 |  |  | 3,247,000,000 |  |
Number of shares issued for acquisition (in shares) | shares | 19 |  |  |  |  |
Equity interest issued or issuable, value | $ 5,900,000,000 |  |  |  |  |
Adjustments for cash and certain assumed liabilities | $ 3,900,000,000 |  |  |  |  |
Increase of intangible assets |  |  |  | 125,000,000 |  |
Decrease of acquired notes receivable |  |  |  | 107,000,000 |  |
Decrease of deferred tax liabilities |  |  |  | 97,000,000 |  |
Decrease in goodwill |  |  |  | 86,000,000 |  |
Goodwill |  |  |  | $ 6,867,000,000 |  |
NFP Acquisition | Tradenames |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Weighted average useful life |  |  |  | 10 years |  |
NFP Acquisition | Customer Relationships |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Weighted average useful life |  |  |  | 20 years |  |
NFP Acquisition | Technology and other |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Weighted average useful life |  |  |  | 7 years |  |
Risk Capital |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Number of business acquired under business combination | acquisition |  |  |  | 10 | 2 |
Goodwill |  |  |  | $ 8,785,000,000 | $ 6,227,000,000 | 6,127,000,000
Risk Capital | NFP Acquisition |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Goodwill |  |  |  | $ 2,700,000,000 |  |
Human Capital |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Number of business acquired under business combination | acquisition |  |  |  | 12 | 1 |
Goodwill |  |  |  | $ 6,449,000,000 | $ 2,187,000,000 | $ 2,165,000,000
Human Capital | NFP Acquisition |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Goodwill |  |  |  | $ 4,200,000,000 |  |
NFP Acquisition |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Number of colleagues (more than) | employee | 7,700 |  |  |  |  |

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