Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Short-term Investments	$ 61	$ 67
Equity Securities, FV-NI	1
Commercial Paper, at Carrying Value	$ 61	$ 67

Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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-Name Accounting Standards Codification
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant