Goodwill and Acquired Intangible Assets (Finite-Lived and Indefinite-Lived Intangible Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 2,157	$ 2,160
Accumulated Amortization	(807)	(772)
Net Amount	1,350	1,388
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	1,195	1,193
Intangible assets, net	2,545	2,581
Exchange and clearing registrations
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	1,257	1,257
Trade names
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	121	121
Licenses
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	52	52
Foreign currency translation adjustment
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	(235)	(237)
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Amount	304	304
Accumulated Amortization	(108)	(97)
Net Amount	196	207
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Amount	2,005	2,005
Accumulated Amortization	(806)	(778)
Net Amount	1,199	1,227
Trade names and other
Finite-Lived Intangible Assets [Line Items]
Gross Amount	58	60
Accumulated Amortization	(16)	(17)
Net Amount	42	43
Foreign currency translation adjustment
Finite-Lived Intangible Assets [Line Items]
Gross Amount	(210)	(209)
Accumulated Amortization	123	120
Net Amount	$ (87)	$ (89)