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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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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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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 210
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Amount, before tax, of increase (decrease) in the cumulative translation adjustment from gain (loss) on foreign currency derivatives that are designated as, and are effective as, economic hedges of a net investment in a foreign entity.

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Hedging Activities - Narrative (Details) £ in Millions, $ in Millions, € in Billions	12 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2017 EUR (€)	Mar. 31, 2017 USD ($)	Mar. 31, 2017 GBP (£)
Derivative [Line Items]
Total debt outstanding		$ 8,107			$ 8,362
Losses from net investment hedges	$ 13
Forward Contracts \| Derivatives Designated for Hedge Accounting
Derivative [Line Items]
Derivative, notional amount		323			243
Foreign Exchange Contract \| Derivatives Not Designated for Hedge Accounting
Derivative [Line Items]
Net gain (losses) on derivatives	$ 5	60	$ (189)
Currency Swap \| Derivatives Designated for Hedge Accounting
Derivative [Line Items]
Derivative, notional amount		546			2,663
Euro Denominated Notes \| Notes
Derivative [Line Items]
Total debt outstanding \| €				€ 1.2
British Pound Sterling Denominated Notes \| Notes
Derivative [Line Items]
Total debt outstanding \| £						£ 450
Canada, Dollars \| Foreign Exchange Contract \| Derivatives Not Designated for Hedge Accounting
Derivative [Line Items]
Derivative, notional amount					173
United Kingdom, Pounds \| Foreign Exchange Contract \| Derivatives Not Designated for Hedge Accounting
Derivative [Line Items]
Derivative, notional amount		$ 876			$ 62