CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustments, tax	$ (1)	$ 75	$ 5
Cash flow hedges adjustment, tax	(3)
Cash flow hedges adjustment, tax		(3)	12
Available-for-sale securities, tax	0	2	0
Prior service cost, tax	(5)	8	0
Amortization of transition obligation, tax	0	0	0
Amortization of prior service cost, tax	2	4	5
Foreign currency exchange (loss) gain, tax	$ 0	$ 0	$ 1

Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit), Tax

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- Definition

Amount of tax expense (benefit), before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
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Amount of tax (expense) benefit of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) of defined benefit plan.

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- Definition

Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

+ References

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- Definition

Amount, after reclassification, of tax expense (benefit) for gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of tax expense (benefit), 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).

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Amount of tax expense (benefit), after reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

+ References

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Amount of tax expense (benefit) for reclassification adjustment from accumulated other comprehensive income (loss) for transition asset (obligation) of defined benefit plan.

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