Financial Instruments (Fair Value Of Short-Term Investments) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Mar. 31, 2021
Financial Instruments
Fair Value	$ 346	$ 1,106	[1]
Short-term investments
Financial Instruments
Debt Securities, Available-for-sale, Amortized Cost	346	1,105
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Fair Value	346	1,106
Short-term investments | Corporate bonds
Financial Instruments
Debt Securities, Available-for-sale, Amortized Cost	148	372
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	148	372
Short-term investments | U.S. Treasury securities
Financial Instruments
Debt Securities, Available-for-sale, Amortized Cost	75	374
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Fair Value	75	375
Short-term investments | U.S. agency securities
Financial Instruments
Debt Securities, Available-for-sale, Amortized Cost	0	3
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	3
Short-term investments | Commercial paper
Financial Instruments
Debt Securities, Available-for-sale, Amortized Cost	39	136
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	39	136
Short-term investments | Debt Security, Government, Non-US [Member]
Financial Instruments
Debt Securities, Available-for-sale, Amortized Cost	30	67
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	30	67
Short-term investments | Asset-backed Securities [Member]
Financial Instruments
Debt Securities, Available-for-sale, Amortized Cost	38	112
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	38	112
Short-term investments | Certificates of Deposit [Member]
Financial Instruments
Debt Securities, Available-for-sale, Amortized Cost	16	41
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 16	$ 41

[1] Derived from audited Consolidated Financial Statements.