Revenue Recognition - Disaggregation of Revenue by Major Products and Service Offerings (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Revenue by Major Products/Service Offerings
Total Revenue	$ 17,162	$ 16,977	$ 33,079	$ 31,519
Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	17,110	17,009	32,979	31,489
Other
Revenue by Major Products/Service Offerings
Revenue	52	(31)	100	30
Software | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	7,761	7,387	14,813	13,722
Software | Hybrid Cloud | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,998	1,796	3,903	3,483
Software | Automation | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,951	1,883	3,692	3,467
Software | Data | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,782	1,499	3,256	2,736
Software | Transaction Processing | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,030	2,208	3,963	4,037
Consulting | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	5,327	5,314	10,599	10,382
Consulting | Strategy and Technology | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,933	2,920	5,829	5,702
Consulting | Intelligent Operations | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,394	2,395	4,770	4,680
Infrastructure | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	3,835	4,142	7,161	7,027
Infrastructure | Hybrid Infrastructure | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	2,570	2,866	4,678	4,512
Infrastructure | Infrastructure Support | Operating Segments
Revenue by Major Products/Service Offerings
Revenue	1,265	1,275	2,483	2,515
Financing | Operating Segments
Revenue by Major Products/Service Offerings
Total Revenue	$ 186	$ 166	$ 406	$ 357