Derivative Instruments (Details) $ in Millions	12 Months Ended
Mar. 31, 2019 USD ($) counterparty	Mar. 31, 2018 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Number of counterparties \| counterparty	5
Maximum exposure	$ 29
Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of foreign currency forward contracts designated as cash flow hedges	277	$ 634
Foreign currency cash flow hedge gain to be reclassified into earnings during next 12 months	1
Loss on derivatives in other comprehensive income (loss)	1
Loss on derivative instruments	10
Designated as Hedging Instrument \| Terminated Interest Rate Swap
Derivative [Line Items]
Notional amount of derivatives outstanding	375
Derivative fair value	5
Hedge gain	5
Designated as Hedging Instrument \| Interest rate swaps
Derivative [Line Items]
Derivative notional amount		635
Not Designated as Hedging Instrument \| Foreign currency forward contracts(1)
Derivative [Line Items]
Notional amount of derivatives outstanding	2,500	$ 3,100
Net Investment Hedging \| Designated as Hedging Instrument \| Foreign currency forward contracts(1)
Derivative [Line Items]
Derivative notional amount	$ 1,700

Concentration Risk, Credit Risk, Number Of Counterparties

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- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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Maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13537-108611

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Nominal or face amount used to calculate payments on the derivative asset.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
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Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The estimated net amount of unrealized gains or losses on foreign currency cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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Fair value as of the balance sheet date of all foreign currency derivative assets not designated as hedging instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The gain relating to components of the gain (loss) on the cash flow hedging instrument excluded from the assessment of cash flow hedge effectiveness. Recognized in earnings.

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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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Amount before tax, after reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

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