Revenue Recognition - Disaggregation of Revenue by Major Products and Service Offerings (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Revenue by Major Products/Service Offerings
Total Revenue	$ 14,541	$ 14,462
Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	14,480	14,354
Other
Revenue by Major Products/Service Offerings
Revenue	61	108
Software | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	6,336	5,899
Software | Hybrid Cloud | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,687	1,510
Software | Automation | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,584	1,391
Software | Data | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,236	1,173
Software | Transaction Processing | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,828	1,824
Consulting | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	5,068	5,186
Consulting | Strategy and Technology | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,782	2,863
Consulting | Intelligent Operations | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,286	2,323
Infrastructure | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	2,886	3,076
Infrastructure | Hybrid Infrastructure | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,646	1,803
Infrastructure | Infrastructure Support | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,240	1,273
Financing | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	$ 191	$ 193