Significant Accounting Policies - Transfers of Financial Assets (Details) - USD ($) $ in Billions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Gross proceeds from transfers of notes and accounts receivable trade	$ 3.8	$ 4.2	$ 3.4
Accounts receivable sold and derecognized that remain uncollected from customers	$ 0.3	$ 0.9	$ 0.5

For transfers of receivables accounted for as sales, the amount of the receivables sold and derecognized that remains uncollected from customers as of the balance sheet date.

No definition available.

Name:	ibm_TransferOfFinancialAssetsAccountedForAsSalesAmountRemainingUncollected
Namespace Prefix:	ibm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant