Hedging Activities - Derivative Instruments Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2018	Mar. 31, 2018
Derivatives designated for hedge accounting
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	$ 105	$ 29
Fair value of derivative, liability	127	229
Derivatives designated for hedge accounting \| Foreign Exchange Contract \| Prepaid expenses and other
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	15	15
Fair value of derivative, liability	0	0
U.S. Dollar notional amount, asset	81	81
Derivatives designated for hedge accounting \| Foreign Exchange Contract \| Other noncurrent assets
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	15	14
Fair value of derivative, liability	0	0
U.S. Dollar notional amount, asset	81	81
Derivatives designated for hedge accounting \| Cross Currency Swap \| Prepaid expenses and other
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	31	0
Derivatives designated for hedge accounting \| Cross Currency Swap \| Other noncurrent assets
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	44	0
Derivatives designated for hedge accounting \| Cross Currency Swap \| Prepaid expenses and other/Other accrued liabilities
Derivatives, Fair Value [Line Items]
U.S. Dollar notional amount, asset	371	504
Derivatives designated for hedge accounting \| Cross Currency Swap \| Other accrued liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative, liability	12	7
Derivatives designated for hedge accounting \| Cross Currency Swap \| Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative, liability	115	222
Derivatives designated for hedge accounting \| Cross Currency Swap \| Non-current Asset / Liability
Derivatives, Fair Value [Line Items]
U.S. Dollar notional amount, asset	3,508	3,508
Derivatives not designated for hedge accounting
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	0	0
Fair value of derivative, liability	0	0
Derivatives not designated for hedge accounting \| Foreign Exchange Contract \| Prepaid expenses and other
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	0	0
Fair value of derivative, liability	0	0
U.S. Dollar notional amount, asset	25	13
Derivatives not designated for hedge accounting \| Foreign Exchange Contract \| Other accrued liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	0	0
Fair value of derivative, liability	0	0
U.S. Dollar, notional amount, liability	$ 15	$ 16

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
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-Section 50
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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
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-URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

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+ References

No definition available.

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