Financial Instruments (Fair Value Of Short-Term Investments) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Mar. 31, 2023
Financial Instruments
Fair Value	$ 359	$ 343	[1]
Short-term investments
Financial Instruments
Cost or Amortized Cost	360	344
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	359	343
Short-term investments | Corporate bonds
Financial Instruments
Cost or Amortized Cost	95	114
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	94	113
Short-term investments | U.S. Treasury securities
Financial Instruments
Cost or Amortized Cost	105	80
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	105	80
Short-term investments | U.S. agency securities
Financial Instruments
Cost or Amortized Cost	19	25
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	19	25
Short-term investments | Commercial paper
Financial Instruments
Cost or Amortized Cost	75	63
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	75	63
Short-term investments | Foreign government securities
Financial Instruments
Cost or Amortized Cost	7	11
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	7	11
Short-term investments | Asset-backed securities
Financial Instruments
Cost or Amortized Cost	41	37
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	41	37
Short-term investments | Certificates of deposit
Financial Instruments
Cost or Amortized Cost	18	14
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 18	$ 14

[1] Derived from audited Consolidated Financial Statements.