Retirement-Related Benefits (Net Periodic Income Cost) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Retirement-related Benefits Disclosures
Defined contribution plans cost	$ 1,384	$ 1,506	$ 1,513
Total retirement-related benefits net periodic cost	2,876	2,389	1,832
Defined Benefit Pension Plans
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	1,195	533	(25)
U.S. Defined Benefit Pension Plans
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	(202)	(507)	(759)
Personal Pension Plan (PPP)
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	(223)	(526)	(774)
Retention Plan
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	21	18	15
Non-U.S. Defined Benefit Pension Plans
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	1,396	1,040	734
PPP and Non-U.S. Defined Benefit Pension Plans
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	1,173	515	(40)
U.S. Defined Contribution Plans
Retirement-related Benefits Disclosures
Defined contribution plans cost	809	885	905
IBM 401(k) Plus Plan
Retirement-related Benefits Disclosures
Defined contribution plans cost	785	857	875
IBM Excess 401(k) Plus Plan
Retirement-related Benefits Disclosures
Defined contribution plans cost	24	29	30
Non-U.S. Defined Contribution Plans
Retirement-related Benefits Disclosures
Defined contribution plans cost	575	621	608
IBM 401(k) Plus Plan and Non-U.S. Defined Contribution Plans
Retirement-related Benefits Disclosures
Defined contribution plans cost	1,361	1,478	1,483
Nonpension Postretirement Plans
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	298	350	345
U.S. Nonpension Postretirement Benefit Plans
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	218	268	269
Non-U.S. Nonpension Postretirement Plans
Retirement-related Benefits Disclosures
Defined benefit plans (income)/cost	79	82	76
U.S. Plans
Retirement-related Benefits Disclosures
Total retirement-related benefits net periodic cost	826	646	415
Non-U.S. Plans
Retirement-related Benefits Disclosures
Total retirement-related benefits net periodic cost	$ 2,051	$ 1,743	$ 1,418

- Definition

The amount of pension and other (such as medical, dental and life insurance) postretirement benefit costs recognized during the period for (1) defined benefit plans (periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss) on assets, prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments) and for (2) defined contribution plans (to the extent that a plan's defined contributions to an individual's account are to be made for periods in which that individual renders services, the net cost for a period is the contribution called for in that period; if a plan calls for contributions for periods after an individual retires or terminates, the estimated cost is accrued during the employee's service period).

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