Income Taxes (Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Line Items]
Accruals, reserves and other expenses	$ 158	$ 141
Tax credit carryforwards	161	137
Stock-based compensation	43	37
Net operating loss & capital loss carryforwards	258	195
Deferred Tax Asset, Intra-entity Transfer, Asset Other than Inventory	1,781	1,818
Total	2,401	2,328
Valuation allowance	(230)	(288)
Deferred tax assets, net of valuation allowance	2,171	2,040
Amortization and Depreciation	(140)	(85)
ASC 606 Revenue Recognition	(21)	(43)
Prepaids and other liabilities	(8)	(10)
Deferred Tax Liabilities, Net	(169)	(138)
Deferred tax assets, net of valuation allowance and deferred tax liabilities	$ 2,002	$ 1,902