XML 56 R49.htm IDEA: XBRL DOCUMENT
v3.25.3

Equity Investments - Schedule of Gains (Losses) on Non-Marketable Securities (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Investments, All Other Investments [Abstract] |  |  |  |
Observable price adjustments on non-marketable equity securities (includes NAV) | $ 0 | $ 0 | $ 1 | $ (2)
Impairment of non-marketable equity securities | 0 | 0 | 0 | (1)
Total income (loss) from equity investments in non-marketable securities, net | $ 0 | $ 0 | $ 1 | $ (3)

X
- Definition Equity Securities Without Readily Determinable Fair Value, Including Fair Value Option, Price Adjustment, Annual Amount + References No definition available. + Details
Name: | arm_EquitySecuritiesWithoutReadilyDeterminableFairValueIncludingFairValueOptionPriceAdjustmentAnnualAmount
Namespace Prefix: | arm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Income (Loss) From Equity Securities without Readily Determinable Fair Value, Including Fair Value Option + References No definition available. + Details
Name: | arm_IncomeLossFromEquitySecuritiesWithoutReadilyDeterminableFairValueIncludingFairValueOption
Namespace Prefix: | arm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of impairment loss on investment in equity security without readily determinable fair value. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 321 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479536/321-10-50-3 + Details
Name: | us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_InvestmentsAllOtherInvestmentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration