Borrowings - Long-Term Debt, Debt Issued (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
U.S dollar. fixed rate notes
Notes Issued
Aggregate amount of debt issued	$ 1,800
U.S dollar. fixed rate notes \| Minimum
Notes Issued
Credit facility term	5 years
Coupon rate (as a percent)	2.20%
U.S dollar. fixed rate notes \| Maximum
Notes Issued
Credit facility term	30 years
Coupon rate (as a percent)	3.43%
Euro fixed-rate notes
Notes Issued
Aggregate amount of debt issued	$ 2,300
Euro fixed-rate notes \| Minimum
Notes Issued
Credit facility term	8 years
Coupon rate (as a percent)	0.875%
Euro fixed-rate notes \| Maximum
Notes Issued
Credit facility term	12 years
Coupon rate (as a percent)	1.25%
IBM Credit LLC \| Fixed rate debt due in 2021 to 2023
Notes Issued
Outstanding debt redeemed		$ 1,750
Aggregate principal redeemed (as a percent)		100.00%
Loss upon redemption on notes		$ (22)

Face (par) amount of debt instrument at time of issuance.

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