Revenues - Transaction and Relationship Revenue (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Revenue	$ 2,079	$ 1,924
Percentage of revenues	100.00%	100.00%
Transaction Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 807	$ 769
Percentage of revenues	39.00%	40.00%
Recurring Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 1,272	$ 1,155
Percentage of revenues	61.00%	60.00%
MA
Disaggregation of Revenue [Line Items]
Revenue	$ 926	$ 859
MA | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 929	$ 862
Percentage of revenues	100.00%	100.00%
MA | DS Banking Product and Service | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 133	$ 141
Percentage of revenues	100.00%	100.00%
MA | Insurance | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 181	$ 163
Percentage of revenues	100.00%	100.00%
MA | KYC | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 118	$ 101
Percentage of revenues	100.00%	100.00%
MA | Decision Solutions (DS) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 432	$ 405
Percentage of revenues	100.00%	100.00%
MA | Research and Insights (R&I) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 255	$ 236
Percentage of revenues	100.00%	100.00%
MA | Data and Information (D&I) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 239	$ 218
Percentage of revenues	100.00%	100.00%
MA | Transaction Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 17	$ 37
MA | Transaction Revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Percentage of revenues	2.00%	4.00%
MA | Transaction Revenue | DS Banking Product and Service | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 6	$ 26
Percentage of revenues	5.00%	18.00%
MA | Transaction Revenue | Insurance | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 4	$ 6
Percentage of revenues	2.00%	4.00%
MA | Transaction Revenue | KYC | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 0
Percentage of revenues	0.00%	0.00%
MA | Transaction Revenue | Decision Solutions (DS) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 10	$ 32
Percentage of revenues	2.00%	8.00%
MA | Transaction Revenue | Research and Insights (R&I) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 3	$ 3
Percentage of revenues	1.00%	1.00%
MA | Transaction Revenue | Data and Information (D&I) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 4	$ 2
Percentage of revenues	2.00%	1.00%
MA | Recurring Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 909	$ 822
MA | Recurring Revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Percentage of revenues	98.00%	96.00%
MA | Recurring Revenue | DS Banking Product and Service | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 127	$ 115
Percentage of revenues	95.00%	82.00%
MA | Recurring Revenue | Insurance | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 177	$ 157
Percentage of revenues	98.00%	96.00%
MA | Recurring Revenue | KYC | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 118	$ 101
Percentage of revenues	100.00%	100.00%
MA | Recurring Revenue | Decision Solutions (DS) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 422	$ 373
Percentage of revenues	98.00%	92.00%
MA | Recurring Revenue | Research and Insights (R&I) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 252	$ 233
Percentage of revenues	99.00%	99.00%
MA | Recurring Revenue | Data and Information (D&I) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 235	$ 216
Percentage of revenues	98.00%	99.00%
MIS
Disaggregation of Revenue [Line Items]
Revenue	$ 1,153	$ 1,065
MIS | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 1,204	$ 1,114
Percentage of revenues	100.00%	100.00%
MIS | Corporate Finance (CFG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 633	$ 564
Percentage of revenues	100.00%	100.00%
MIS | Structured Finance (SFG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 137	$ 138
Percentage of revenues	100.00%	100.00%
MIS | Financial Institutions (FIG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 194	$ 191
Percentage of revenues	100.00%	100.00%
MIS | Public, Project and Infrastructure Finance (PPIF) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 176	$ 163
Percentage of revenues	100.00%	100.00%
MIS | MIS Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 13	$ 9
Percentage of revenues	100.00%	100.00%
MIS | Transaction Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 790	$ 732
MIS | Transaction Revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Percentage of revenues	69.00%	69.00%
MIS | Transaction Revenue | Corporate Finance (CFG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 484	$ 427
Percentage of revenues	76.00%	76.00%
MIS | Transaction Revenue | Structured Finance (SFG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 74	$ 78
Percentage of revenues	54.00%	57.00%
MIS | Transaction Revenue | Financial Institutions (FIG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 105	$ 109
Percentage of revenues	54.00%	57.00%
MIS | Transaction Revenue | Public, Project and Infrastructure Finance (PPIF) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 124	$ 116
Percentage of revenues	70.00%	71.00%
MIS | Transaction Revenue | MIS Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 3	$ 2
Percentage of revenues	23.00%	22.00%
MIS | Recurring Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 363	$ 333
MIS | Recurring Revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Percentage of revenues	31.00%	31.00%
MIS | Recurring Revenue | Corporate Finance (CFG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 149	$ 137
Percentage of revenues	24.00%	24.00%
MIS | Recurring Revenue | Structured Finance (SFG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 63	$ 60
Percentage of revenues	46.00%	43.00%
MIS | Recurring Revenue | Financial Institutions (FIG) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 89	$ 82
Percentage of revenues	46.00%	43.00%
MIS | Recurring Revenue | Public, Project and Infrastructure Finance (PPIF) | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 52	$ 47
Percentage of revenues	30.00%	29.00%
MIS | Recurring Revenue | MIS Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 10	$ 7
Percentage of revenues	77.00%	78.00%