Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Income Tax Footnote Disclosure [Line Items]
Deferred Tax Asset, Intra-entity Transfer, Asset Other than Inventory	$ 1,170
Gross unrecognized tax benefits	$ 90
Deferred Tax Asset, Period Of Reversal	20 years
Operating Loss Carryforward, Term	7 years
Deferred Tax Asset, Increase (Decrease), Intra-Entity Transfer, Asset Other Than Inventory	$ 100
Effective tax rates	(226.00%)	8.20%
United States statutory tax rate	21.00%
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 52
Pro Forma [Member]
Income Tax Footnote Disclosure [Line Items]
Effective tax rates	21.60%