Retirement-Related Benefits (Narrative) (Details 4) - USD ($) $ in Millions	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Non-U.S. Defined Benefit and Multi-employer Plan
Expected current year contributions to non-U.S. defined benefit plans						$ 600
Year-to-date contributions to non-U.S. defined benefit plans						271
Non-US Defined Benefit Pension Plans
Multi-employer plans/other costs	$ 16			$ 36		$ 272	$ 131
Non-US Defined Benefit Pension Plans | SG&A expense | Litigation in Spain regarding defined benefit and defined contribution plans
Multi-employer plans/other costs		$ 230	$ 73	$ 20	$ 55			$ 148