Property, Plant and Equipment (Components of Property Plant and Equipment, Specifically Leased Devices) (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Document Period End Date	Jun. 30, 2017
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ (15,333)	$ (14,503)
Property, plant and equipment, net	18,866	19,209
Leased devices [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	7,699	7,276
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(3,363)	(3,114)
Property, plant and equipment, net	$ 4,336	$ 4,162