Summary of Significant Accounting Policies (Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Deferred Tax Assets, Net	$ 2,241	$ 2,002
Deferred Tax Assets, Valuation Allowance	296	230
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability		141	$ 1,760
Income Tax Expense (Benefit)	$ 292	$ 180	(1,531)
Swiss Federal Tax Administration (FTA) [Member]
Deferred Tax Assets, Net			1,840
Deferred Tax Assets, Valuation Allowance			131
Reduction in Taxes [Member]
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability			393
Income Tax Expense (Benefit)			$ 80