Revenue from Contracts with Customers (Revenue by Product, Service and Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	$ 1,315	$ 1,146	$ 3,857	$ 3,422
Operating segments \| Capital Access Platforms: \| Data & Listing Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	204	190	594	562
Operating segments \| Capital Access Platforms: \| Index
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	206	182	595	517
Operating segments \| Capital Access Platforms: \| Workflow & Insights
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	136	129	399	381
Operating segments \| Financial Technology \| Financial Crime Management Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	84	69	241	200
Operating segments \| Financial Technology \| Regulatory Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	109	68	315	253
Operating segments \| Financial Technology \| Capital Markets Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	264	234	796	730
Operating segments \| Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	303	266	890	752
Reconciling items \| Other revenues
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	$ 9	$ 8	$ 27	$ 27