Property, Plant and Equipment (Components of Property Plant and Equipment, Specifically Leased Devices) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Apr. 01, 2019	Mar. 31, 2019
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment		$ 41,709
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ (20,418)	(20,512)	$ (20,539)
Property, plant and equipment, net	20,562	$ 21,197	21,201
Leased devices [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	10,557		10,972
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(4,179)		(4,360)
Property, plant and equipment, net	$ 6,378		$ 6,612