Retirement-Related Benefits (Narrative) (Details 4) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Non-U.S. Defined Benefit and Multi-employer Plan
Expected current year contributions to non-U.S. defined benefit plans	$ 500
Year-to-date contributions to non-U.S. defined benefit plans	107
Non-U.S. Defined Benefit and Multi-employer Plan | U.S. Treasury securities
Year-to-date contributions to non-U.S. defined benefit plans	42
Non-U.S. Defined Benefit and Multi-employer Plan | Cash
Year-to-date contributions to non-U.S. defined benefit plans	$ 65
U.S. Pension Plans
Projected long-term rate of return on plan assets for the next fiscal year (as a percent)	6.25%		7.00%
U.S. Pension Plans | Equity securities
Target allocation (as a percent)	21.00%		34.00%
U.S. Pension Plans | Debt securities
Target allocation (as a percent)	70.00%		56.00%
U.S. Pension Plans | Other investments
Target allocation (as a percent)	9.00%		10.00%
Non-US Pension Plans
Multi-employer plans/other costs	$ 18	$ 248
Non-US Pension Plans | SG&A expense | Litigation in Spain regarding defined benefit and defined contribution plans
Multi-employer plans/other costs		$ 230	$ 233
U.S. Defined Benefit Non Pension Postretirement Plans | U.S. Treasury securities
Year-to-date contributions to non-U.S. defined benefit plans	100
U.S. Defined Benefit Non Pension Postretirement Plans | Cash
Year-to-date contributions to non-U.S. defined benefit plans	$ 126