Revenues - Transaction and Relationship Revenue (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Revenue	$ 1,898	$ 1,817	$ 3,822	$ 3,603
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
Transaction Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 699	$ 730	$ 1,468	$ 1,454
Percentage of revenues	37.00%	40.00%	38.00%	40.00%
Recurring Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 1,199	$ 1,087	$ 2,354	$ 2,149
Percentage of revenues	63.00%	60.00%	62.00%	60.00%
MA
Disaggregation of Revenue [Line Items]
Revenue	$ 888	$ 802	$ 1,747	$ 1,601
MA \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 891	$ 806	$ 1,753	$ 1,608
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MA \| DS Banking Product and Service \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 138	$ 131	$ 279	$ 265
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MA \| Insurance \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 168	$ 147	$ 331	$ 291
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MA \| KYC \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 107	$ 88	$ 208	$ 175
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MA \| Decision Solutions (DS)
Disaggregation of Revenue [Line Items]
Revenue	$ 413	$ 366
MA \| Decision Solutions (DS) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 413	$ 366	$ 818	$ 731
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MA \| Research and Insights (R&I)
Disaggregation of Revenue [Line Items]
Revenue	$ 249	$ 226
MA \| Research and Insights (R&I) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 249	$ 226	$ 485	$ 448
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MA \| Data and Information (D&I)
Disaggregation of Revenue [Line Items]
Revenue	$ 226	$ 210
MA \| Data and Information (D&I) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 226	$ 210	$ 444	$ 422
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MA \| Transaction Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 36	$ 38	$ 73	$ 85
MA \| Transaction Revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Percentage of revenues	4.00%	5.00%	4.00%	5.00%
MA \| Transaction Revenue \| DS Banking Product and Service \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 25	$ 28	$ 51	$ 57
Percentage of revenues	18.00%	21.00%	18.00%	22.00%
MA \| Transaction Revenue \| Insurance \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 6	$ 4	$ 12	$ 14
Percentage of revenues	4.00%	3.00%	4.00%	5.00%
MA \| Transaction Revenue \| KYC \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 1	$ 0	$ 3
Percentage of revenues	0.00%	1.00%	0.00%	2.00%
MA \| Transaction Revenue \| Decision Solutions (DS) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 31	$ 33	$ 63	$ 74
Percentage of revenues	8.00%	9.00%	8.00%	10.00%
MA \| Transaction Revenue \| Research and Insights (R&I) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 3	$ 3	$ 6	$ 6
Percentage of revenues	1.00%	1.00%	1.00%	1.00%
MA \| Transaction Revenue \| Data and Information (D&I) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 2	$ 2	$ 4	$ 5
Percentage of revenues	1.00%	1.00%	1.00%	1.00%
MA \| Recurring Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 852	$ 764	$ 1,674	$ 1,516
MA \| Recurring Revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Percentage of revenues	96.00%	95.00%	96.00%	95.00%
MA \| Recurring Revenue \| DS Banking Product and Service \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 113	$ 103	$ 228	$ 208
Percentage of revenues	82.00%	79.00%	82.00%	78.00%
MA \| Recurring Revenue \| Insurance \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 162	$ 143	$ 319	$ 277
Percentage of revenues	96.00%	97.00%	96.00%	95.00%
MA \| Recurring Revenue \| KYC \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 107	$ 87	$ 208	$ 172
Percentage of revenues	100.00%	99.00%	100.00%	98.00%
MA \| Recurring Revenue \| Decision Solutions (DS) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 382	$ 333	$ 755	$ 657
Percentage of revenues	92.00%	91.00%	92.00%	90.00%
MA \| Recurring Revenue \| Research and Insights (R&I) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 246	$ 223	$ 479	$ 442
Percentage of revenues	99.00%	99.00%	99.00%	99.00%
MA \| Recurring Revenue \| Data and Information (D&I) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 224	$ 208	$ 440	$ 417
Percentage of revenues	99.00%	99.00%	99.00%	99.00%
MIS
Disaggregation of Revenue [Line Items]
Revenue	$ 1,010	$ 1,015	$ 2,075	$ 2,002
MIS \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 1,060	$ 1,064	$ 2,174	$ 2,098
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MIS \| Corporate Finance (CFG)
Disaggregation of Revenue [Line Items]
Revenue	$ 512	$ 525
MIS \| Corporate Finance (CFG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 512	$ 525	$ 1,076	$ 1,054
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MIS \| Structured Finance (SFG)
Disaggregation of Revenue [Line Items]
Revenue	$ 135	$ 131
MIS \| Structured Finance (SFG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 135	$ 131	$ 273	$ 245
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MIS \| Financial Institutions (FIG)
Disaggregation of Revenue [Line Items]
Revenue	$ 191	$ 195
MIS \| Financial Institutions (FIG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 191	$ 195	$ 382	$ 390
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MIS \| Public, Project and Infrastructure Finance (PPIF)
Disaggregation of Revenue [Line Items]
Revenue	$ 162	$ 154
MIS \| Public, Project and Infrastructure Finance (PPIF) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 162	$ 154	$ 325	$ 295
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MIS \| MIS Other
Disaggregation of Revenue [Line Items]
Revenue	$ 10	$ 10
MIS \| MIS Other \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 10	$ 10	$ 19	$ 18
Percentage of revenues	100.00%	100.00%	100.00%	100.00%
MIS \| Transaction Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 663	$ 692	$ 1,395	$ 1,369
MIS \| Transaction Revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Percentage of revenues	66.00%	68.00%	67.00%	68.00%
MIS \| Transaction Revenue \| Corporate Finance (CFG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 365	$ 388	$ 792	$ 787
Percentage of revenues	71.00%	74.00%	74.00%	75.00%
MIS \| Transaction Revenue \| Structured Finance (SFG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 74	$ 76	$ 152	$ 135
Percentage of revenues	55.00%	58.00%	56.00%	55.00%
MIS \| Transaction Revenue \| Financial Institutions (FIG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 108	$ 115	$ 217	$ 237
Percentage of revenues	57.00%	59.00%	57.00%	61.00%
MIS \| Transaction Revenue \| Public, Project and Infrastructure Finance (PPIF) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 113	$ 110	$ 229	$ 206
Percentage of revenues	70.00%	71.00%	70.00%	70.00%
MIS \| Transaction Revenue \| MIS Other \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 3	$ 3	$ 5	$ 4
Percentage of revenues	30.00%	30.00%	26.00%	22.00%
MIS \| Recurring Revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 347	$ 323	$ 680	$ 633
MIS \| Recurring Revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Percentage of revenues	34.00%	32.00%	33.00%	32.00%
MIS \| Recurring Revenue \| Corporate Finance (CFG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 147	$ 137	$ 284	$ 267
Percentage of revenues	29.00%	26.00%	26.00%	25.00%
MIS \| Recurring Revenue \| Structured Finance (SFG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 61	$ 55	$ 121	$ 110
Percentage of revenues	45.00%	42.00%	44.00%	45.00%
MIS \| Recurring Revenue \| Financial Institutions (FIG) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 83	$ 80	$ 165	$ 153
Percentage of revenues	43.00%	41.00%	43.00%	39.00%
MIS \| Recurring Revenue \| Public, Project and Infrastructure Finance (PPIF) \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 49	$ 44	$ 96	$ 89
Percentage of revenues	30.00%	29.00%	30.00%	30.00%
MIS \| Recurring Revenue \| MIS Other \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	$ 7	$ 7	$ 14	$ 14
Percentage of revenues	70.00%	70.00%	74.00%	78.00%