Financial Assets & Liabilities - Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financial assets and financial liabilities measured at fair value on a recurring basis:
Debt securities - current	$ 1,753	$ 600
Recurring
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	4,927	2,766
Total assets	7,908	4,608
Total liabilities	1,263	162
Recurring \| Prepaid expenses and other current assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	1,008	358
Recurring \| Investments and sundry assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	4	40
Recurring \| Other accrued expenses and liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities	475	60
Recurring \| Other liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities	603	103
Recurring \| Level 1
Financial assets and financial liabilities measured at fair value on a recurring basis:
Equity investments		0
Recurring \| Level 1 \| Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	732	263
Recurring \| Level 2
Financial assets and financial liabilities measured at fair value on a recurring basis:
Secured borrowing	184
Debt securities - current	1,753	600
Recurring \| Level 2 \| Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivatives designated as hedging - Assets	1	12
Derivatives designated as hedging - Liabilities	339
Recurring \| Level 2 \| Foreign exchange contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivatives designated as hedging - Assets	998	359
Derivatives designated as hedging - Liabilities	531	117
Derivatives not designated as hedging - Assets	13	21
Derivatives not designated as hedging - Liabilities	31	42
Recurring \| Level 2 \| Time deposits and certificates of deposit
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	4,195	1,903
Recurring \| Level 2 \| U.S. government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents		599
Recurring \| Level 1 And 2 \| Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivatives not designated as hedging - Assets		6
Derivatives not designated as hedging - Liabilities	178	4
Recurring \| Level 2 And 3
Financial assets and financial liabilities measured at fair value on a recurring basis:
Debt securities - noncurrent	31	37
Recurring \| Kyndryl Holdings, Inc \| Level 1
Financial assets and financial liabilities measured at fair value on a recurring basis:
Equity investments	$ 184	$ 807

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

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Aggregate fair value of all derivative assets designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations.

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Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and elected not to be offset.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

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Fair value of financial and nonfinancial obligations.

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