Revenue from Contracts with Customers (Revenue by Product, Service and Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	$ 1,481	$ 1,315	$ 4,388	$ 3,857
Operating segments \| Capital Access Platforms \| Data & Listing Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	224	204	655	594
Operating segments \| Capital Access Platforms \| Index
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	286	206	778	595
Operating segments \| Capital Access Platforms \| Workflow & Insights
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	131	124	387	363
Operating segments \| Financial Technology \| Financial Crime Management Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	103	84	294	241
Operating segments \| Financial Technology \| Regulatory Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	123	109	361	315
Operating segments \| Financial Technology \| Capital Markets Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	303	264	930	796
Operating segments \| Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	309	303	965	890
Reconciling items \| Other revenues
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	$ 2	$ 21	$ 18	$ 63