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, 2024	Dec. 31, 2023	Jun. 30, 2023
Assets acquired:
Goodwill		$ 15,281	$ 8,414
Liabilities assumed:
Funds held on behalf of clients		7,309		$ 7,538
2024 Acquisition
Consideration transferred:
Cash		3,356
Deferred and contingent consideration		7
Class A ordinary shares issued		5,882
Aggregate consideration transferred		9,245
Assets acquired:
Cash and cash equivalents		296
Receivables		324
Fiduciary assets		417
Goodwill		7,022
Other intangible assets:
Operating lease right-of-use assets		145
Current assets		113
Non-current assets		170
Total assets acquired		15,188
Liabilities assumed:
Accounts payable and accrued liabilities		291
Fiduciary liabilities		417
Current liabilities		227
Long-term debt		3,422
Non-current operating lease liabilities		127
Deferred tax liabilities		1,129
Non-current liabilities		142
Total liabilities assumed		5,755
Less: Fair value of redeemable noncontrolling interests		(103)
Less: Fair value of nonredeemable noncontrolling interests		(85)
Net assets acquired		9,245
Funds held on behalf of clients		283
2024 Acquisition | Customer-related and contract-based
Other intangible assets:
Intangible assets		5,875
2024 Acquisition | Tradenames
Other intangible assets:
Intangible assets		800
2024 Acquisition | Technology and other
Other intangible assets:
Intangible assets		26
NFP Acquisition
Consideration transferred:
Cash	$ 3,200	3,247
Deferred and contingent consideration		0
Class A ordinary shares issued		5,882
Aggregate consideration transferred	$ 9,100	9,129
Assets acquired:
Cash and cash equivalents		293
Receivables		321
Fiduciary assets		411
Goodwill		6,953
Other intangible assets:
Operating lease right-of-use assets		143
Current assets		110
Non-current assets		169
Total assets acquired		15,050
Liabilities assumed:
Accounts payable and accrued liabilities		283
Fiduciary liabilities		411
Current liabilities		227
Long-term debt		3,422
Non-current operating lease liabilities		125
Deferred tax liabilities		1,123
Non-current liabilities		142
Total liabilities assumed		5,733
Less: Fair value of redeemable noncontrolling interests		(103)
Less: Fair value of nonredeemable noncontrolling interests		(85)
Net assets acquired		9,129
NFP Acquisition | Customer-related and contract-based
Other intangible assets:
Intangible assets		5,825
NFP Acquisition | Tradenames
Other intangible assets:
Intangible assets		800
NFP Acquisition | Technology and other
Other intangible assets:
Intangible assets		25
Other Acquisitions
Consideration transferred:
Cash		109
Deferred and contingent consideration		7
Class A ordinary shares issued		0
Aggregate consideration transferred		116
Assets acquired:
Cash and cash equivalents		3
Receivables		3
Fiduciary assets		6
Goodwill		69
Other intangible assets:
Operating lease right-of-use assets		2
Current assets		3
Non-current assets		1
Total assets acquired		138
Liabilities assumed:
Accounts payable and accrued liabilities		8
Fiduciary liabilities		6
Current liabilities		0
Long-term debt		0
Non-current operating lease liabilities		2
Deferred tax liabilities		6
Non-current liabilities		0
Total liabilities assumed		22
Less: Fair value of redeemable noncontrolling interests		0
Less: Fair value of nonredeemable noncontrolling interests		0
Net assets acquired		116
Other Acquisitions | Customer-related and contract-based
Other intangible assets:
Intangible assets		50
Other Acquisitions | Tradenames
Other intangible assets:
Intangible assets		0
Other Acquisitions | Technology and other
Other intangible assets:
Intangible assets		$ 1