Property, Plant and Equipment (Components of Property Plant and Equipment, Specifically Leased Devices) (Details) - USD ($) $ in Millions	9 Months Ended
	Dec. 31, 2016	Mar. 31, 2016
Property, Plant and Equipment [Line Items]
Document Period End Date	Dec. 31, 2016
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ (13,341)	$ (9,692)
Property, plant and equipment, net	19,333	20,297
Leased devices [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	7,099	4,913
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(2,645)	(1,267)
Property, plant and equipment, net	$ 4,454	$ 3,646