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Subsequent Events (Details) - Subsequent event - USD ($) $ / shares in Units, $ in Millions	Oct. 26, 2021	Nov. 01, 2021	Oct. 15, 2021
Subsequent Events
Dividend declared, date	Oct. 26, 2021
Dividend declared (in dollars per share)	$ 1.64
Dividend payable, date	Dec. 10, 2021
Shareholders of record, date	Nov. 10, 2021
Variable-rate term loan \| Kyndryl Holdings, Inc
Subsequent Events
Aggregate amount of debt issued		$ 500
Debt term		3 years
Senior unsecured fixed-rate note \| Kyndryl Holdings, Inc
Subsequent Events
Aggregate amount of debt issued			$ 2,400
Senior unsecured fixed-rate note \| Minimum \| Kyndryl Holdings, Inc
Subsequent Events
Debt term			5 years
Coupon rate (as a percent)			2.05%
Senior unsecured fixed-rate note \| Maximum \| Kyndryl Holdings, Inc
Subsequent Events
Debt term			20 years
Coupon rate (as a percent)			4.10%