Acquisitions, Dispositions, Goodwill and Other Intangible Assets (Intangible Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 20,427	$ 20,038
Accumulated Amortization	6,556	6,251
Unamortized: Trademarks and Other	2,124	2,096
Total Intangible Assets Gross Excluding Goodwill	22,551	22,134
Service portfolios [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	2,285	2,178
Accumulated Amortization	1,636	1,534
Patents and trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	408	399
Accumulated Amortization	243	233
Collaboration intangible assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	4,198	4,109
Accumulated Amortization	444	384
Customer relationships and other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	13,536	13,352
Accumulated Amortization	$ 4,233	$ 4,100