FINANCIAL ASSETS AND LIABILITIES - Gains and Losses (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative instruments in cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Earnings and Other Comprehensive Income - Recognized in OCI	$ 4
Gain (Loss) Recognized in Earnings and Other Comprehensive Income - Reclassified from AOCI	1	$ 6	$ 31
Gain (Loss) Recognized in Earnings and Other Comprehensive Income - Amounts Excluded from Effectiveness Testing	0	0	0
Not designated as hedging instruments - economic hedges
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (loss) from derivatives	4	6	20
Foreign exchange contracts \| Derivative instruments in cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Earnings and Other Comprehensive Income - Recognized in OCI	4
Cost of services. \| Derivative instruments in cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Earnings and Other Comprehensive Income - Reclassified from AOCI	1	7	19
Selling, general and administrative expense. \| Derivative instruments in cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Earnings and Other Comprehensive Income - Reclassified from AOCI		(1)	12
Other expenses \| Foreign exchange contracts \| Not designated as hedging instruments - economic hedges
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (loss) from derivatives	$ 4	$ 6	$ 20

Amount of gain (loss) from excluded component of derivative hedge, recognized in earnings. Excludes recognition under systematic and rational method.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 20
-Section 45
-Paragraph 1A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121577181&loc=SL110061172-113977

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624171-113959

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 45
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