Segments - Pre-Tax Income Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021		Jun. 30, 2022	Jun. 30, 2021
Pre-tax income from continuing operations
Amortization of acquired intangible assets	$ (458.0)	$ (456.0)		$ (919.0)	$ (903.0)
Acquisition-related (charges)/income	(2.0)	(18.0)		(9.0)	(34.0)
Non-operating retirement-related (costs)/income	(192.0)	(317.0)		(394.0)	(649.0)
Kyndryl-related impacts	(145.0)			(367.0)
Other - divested businesses	160.0	(50.0)		109.0	(65.0)
Income from continuing operations before income taxes	1,722.0	912.0	[1]	2,345.0	1,155.0	[1]
Business Segments
Pre-tax income from continuing operations
Income from continuing operations before income taxes	2,577.0	1,949.0		4,342.0	3,274.0
Internal transactions
Pre-tax income from continuing operations
Income from continuing operations before income taxes	(4.0)	5.0		(15.0)	(4.0)
Unallocated corporate amounts
Pre-tax income from continuing operations
Income from continuing operations before income taxes	$ (215.0)	$ (202.0)		$ (403.0)	$ (464.0)

[1] Reclassified to reflect discontinued operations presentation.