Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020
Income Tax Footnote Disclosure [Line Items]
Gross unrecognized tax benefits	$ 660	$ 90	$ 983
Effective Income Tax Rate Reconciliation, Percent	22.00%	226.00%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Deferred Tax Asset, Intra-entity Transfer, Asset Other than Inventory		$ 1,170
Deferred Tax Asset, Period Of Reversal	20 years
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	$ 0
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(344)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	18
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	0
Unrecognized Tax Benefits Changes Resulting From Foreign Currency Translation	3
Taxes Payable, Current	148		$ 31
Amount of foreign earnings that is not permanently reinvested (available for repatriation without a material cost)	1,200
Pro Forma [Member]
Income Tax Footnote Disclosure [Line Items]
Effective Income Tax Rate Reconciliation, Percent		22.00%
Reclassification, Other [Member]
Income Tax Footnote Disclosure [Line Items]
Taxes Payable, Current	80
Foreign Tax Authority [Member]
Income Tax Footnote Disclosure [Line Items]
Cash, Cash Equivalents, and Short-term Investments	3,200
Swiss Federal Tax Administration (FTA) [Member]
Income Tax Footnote Disclosure [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 131