Acquisitions and Dispositions of Businesses - Schedule of Consideration Transferred and Preliminary Value of Intangible Assets (Details) - USD ($) $ in Millions		6 Months Ended
	Apr. 25, 2024	Jun. 30, 2025	Dec. 31, 2024	Jun. 30, 2024
Assets acquired:
Goodwill		$ 16,024	$ 15,234
Liabilities assumed:
Payments to acquire businesses, escrow deposits			$ 416
Funds held on behalf of clients		8,315		$ 7,309
2025 Acquisitions
Consideration transferred:
Cash		631
Deferred and contingent consideration		38
Aggregate consideration transferred		669
Assets acquired:
Cash and cash equivalents		33
Goodwill		362
Intangible assets		322
Other assets		126
Total assets acquired		810
Liabilities assumed:
Total liabilities assumed		141
Net assets acquired		669
Funds held on behalf of clients		42
NFP Acquisition
Consideration transferred:
Cash	$ 3,200	3,247
Class A ordinary shares issued		5,882
Aggregate consideration transferred	$ 9,100	9,129
Assets acquired:
Cash and cash equivalents		294
Receivables		329
Fiduciary assets		411
Goodwill		6,838
Operating lease right-of-use assets		138
Current assets		82
Non-current assets		108
Total assets acquired		14,975
Liabilities assumed:
Accounts payable and accrued liabilities		283
Fiduciary liabilities		411
Current liabilities		241
Long-term debt		3,422
Non-current operating lease liabilities		125
Deferred tax liabilities		1,013
Non-current liabilities		158
Total liabilities assumed		5,653
Less: Fair value of redeemable noncontrolling interests		(108)
Less: Fair value of nonredeemable noncontrolling interests		(85)
Net assets acquired		9,129
Funds held on behalf of clients		277
NFP Acquisition | Customer-related and contract-based
Assets acquired:
Other intangible assets		5,950
NFP Acquisition | Tradenames
Assets acquired:
Other intangible assets		800
NFP Acquisition | Technology and other
Assets acquired:
Other intangible assets		$ 25