Income Taxes - Reconciliation of Potential Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Reconciliation of the beginning and ending amount of potential tax benefits
Beginning of year	$ 104	$ 548	$ 79
Increases in prior year position	4	41	0
Increases in current year position	17	13	470
Decreases in prior year position	0	(474)	(1)
Settlements with taxing authorities	0	(24)	0
Lapse of statute of limitations	0	0	0
End of year	$ 125	$ 104	$ 548

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 217
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-217

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-Paragraph 15A
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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
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- Definition

Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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- Definition

Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

+ References

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