Goodwill and Other Intangible Assets - Changes in the Net Carrying Amount of the Components of Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets, gross carrying amount	$ 5,638	$ 5,621	$ 5,677
Finite-lived intangible assets, accumulated amortization	(3,622)	(3,348)	(3,122)
Finite-lived intangible assets, net amount	2,016	2,273	2,555
Intangible assets acquired	7	72
Intangible asset disposals	(13)	(6)
Amortization	(263)	(312)	(369)
Foreign exchange	12	(36)
Client relationships [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets, gross carrying amount	3,807	3,760	3,794
Finite-lived intangible assets, accumulated amortization	(2,514)	(2,282)	(2,118)
Finite-lived intangible assets, net amount	1,293	1,478	1,676
Intangible assets acquired	7	67
Intangible asset disposals	0	(1)
Amortization	(204)	(230)
Foreign exchange	12	(34)
Software [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets, gross carrying amount	729	725	742
Finite-lived intangible assets, accumulated amortization	(726)	(712)	(701)
Finite-lived intangible assets, net amount	3	13	41
Intangible assets acquired	0	4
Intangible asset disposals	0	0
Amortization	(10)	(31)
Foreign exchange	0	(1)
Trademark and trade name [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets, gross carrying amount	1,039	1,038	1,039
Finite-lived intangible assets, accumulated amortization	(342)	(298)	(257)
Finite-lived intangible assets, net amount	697	740	782
Intangible assets acquired	0	1
Intangible asset disposals	0	0
Amortization	(43)	(42)
Foreign exchange	0	(1)
Other [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets, gross carrying amount	63	98	102
Finite-lived intangible assets, accumulated amortization	(40)	(56)	(46)
Finite-lived intangible assets, net amount	23	42	$ 56
Intangible assets acquired	0	0
Intangible asset disposals	(13)	(5)
Amortization	(6)	(9)
Foreign exchange	$ 0	$ 0