Income Taxes - Change in Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Balance at beginning of the year	$ 52	$ 43	$ 22
Increases related to positions taken during the current year	14	3	2
Increases recorded in current year related to positions taken during prior years	0	11	19
Decreases recorded in current year related to positions taken during prior years	(1)	0	0
Settlements	0	(3)	0
Expirations due to lapse of statute	(2)	(2)	0
Balance at end of year	$ 63	$ 52	$ 43

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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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-15A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 10B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482525/740-10-45-10B

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

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

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-URI https://asc.fasb.org/1943274/2147482685/740-10-50-15A

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