TRANSACTIONS WITH FORMER PARENT - Related Party Revenue and Purchases (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended						24 Months Ended
	Mar. 31, 2022		Mar. 31, 2021	Mar. 31, 2024		Mar. 31, 2023		Dec. 31, 2021		Mar. 31, 2024	Aug. 11, 2022
Related Party Transaction [Line Items]
Revenues	$ 4,431	[1]	$ 4,771	$ 16,052	[1]	$ 17,026	[1]	$ 18,657	[1]
Cost of services	3,824	[2]	4,318	13,189	[2]	14,498	[2]	16,550	[2]
Payment for purchase of hardware from IBM	180		180	651		865		752
Other noncurrent assets				67		267				$ 67
Property and equipment, net				2,674		2,779				2,674
Related Party
Related Party Transaction [Line Items]
Revenues	236		154			287		704
Cost of services	924		$ 1,006			1,382		3,979
IBM
Related Party Transaction [Line Items]
Ownership interest transferred											19.90%
IBM | Related Party
Related Party Transaction [Line Items]
Revenues	236					287		704		0
Cost of services	924					1,400		4,000		0
IBM | Related Party | Hardware, software and services
Related Party Transaction [Line Items]
Payment for purchase of hardware from IBM	$ 25					89		$ 299
Other noncurrent assets						$ 265
Property and equipment, net				$ 265						$ 265
Upgraded hardware period						2 years

[1] Including related-party revenue of $287 for the year ended March 31, 2023, $236 for the three months ended March 31, 2022, and $704 for the year ended December 31, 2021

[2] Including related-party cost of service of $1,382 for the year ended March 31, 2023, $924 for the three months ended March 31, 2022, and $3,979 for the year ended December 31, 2021