Income Taxes (Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Line Items]
Accruals, reserves and other expenses	$ 141	$ 101
Tax credit carryforwards	137	140
Stock-based compensation	37	33
Net operating loss & capital loss carryforwards	195	22
Deferred Tax Asset, Intra-entity Transfer, Asset Other than Inventory	1,818	0
Total	2,328	296
Valuation allowance	(288)	(162)
Deferred tax assets, net of valuation allowance	2,040	134
Amortization and Depreciation	(85)	(28)
ASC 606 Revenue Recognition	(43)	(66)
Prepaids and other liabilities	(10)	(7)
Deferred Tax Liabilities, Net	(138)	(101)
Deferred tax assets, net of valuation allowance and deferred tax liabilities	$ 1,902	$ 33