FINANCIAL ASSETS AND LIABILITIES - Effect of Hedge Activity on Income and Expense (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Cost of services	[1]	$ 16,570	$ 17,143	$ 17,682
Selling, general and administrative expenses		2,776	2,948	2,970
Other (income) and expense		35	25	(29)
Cost of services.
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) from Hedge Activity		1	7	19
Selling, general and administrative expense
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) from Hedge Activity			(1)	12
Other (income) and expense
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) from Hedge Activity		$ 4	$ 6	$ 20

[1] Including related-party cost of service of $3,979 in 2021, $3,767 in 2020 and $3,592 in 2019