Revenue Recognition - Disaggregation of Revenue by Major Products and Service Offerings (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenue by Major Products/Service Offerings
Total Revenue	$ 16,331	$ 14,968	$ 47,849	$ 45,199
Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	16,292	14,900	47,782	44,985
Other
Revenue by Major Products/Service Offerings
Revenue	38	68	68	214
Software | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	7,209	6,524	20,932	19,162
Software | Hybrid Cloud | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,886	1,659	5,369	4,716
Software | Automation | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,934	1,563	5,401	4,574
Software | Data | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,459	1,352	4,194	3,902
Software | Transaction Processing | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,930	1,951	5,967	5,970
Consulting | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	5,324	5,152	15,706	15,517
Consulting | Strategy and Technology | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,905	2,856	8,607	8,613
Consulting | Intelligent Operations | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,419	2,297	7,100	6,904
Infrastructure | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	3,559	3,042	10,586	9,764
Infrastructure | Hybrid Infrastructure | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,263	1,765	6,775	5,928
Infrastructure | Infrastructure Support | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,296	1,277	3,811	3,835
Financing | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	$ 200	$ 181	$ 557	$ 543