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Related Party Transactions (Details) - USD ($) | 1 Months Ended | 3 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Feb. 28, 2023 | Jun. 30, 2025 | Jun. 30, 2024 | Mar. 31, 2025 | Mar. 31, 2024 | Mar. 31, 2022
Related Party Transaction [Line Items] |  |  |  |  |  |
Revenue |  | $ 1,053,000,000 | $ 939,000,000 |  |  |
Operating expenses |  | 909,000,000 | 724,000,000 |  |  |
Accounts receivable, net |  | 1,315,000,000 |  | $ 1,107,000,000 |  |
Other current liabilities (including payables to related parties of $10 and $11 as of June 30, 2025 and March 31, 2025, respectively) |  | 512,000,000 |  | 426,000,000 |  |
Contract liabilities |  | 259,000,000 |  | 209,000,000 |  |
Additional (reversal of) provision |  | (1,000,000) | 16,000,000 |  |  |
Allowance for current expected credit losses |  | (19,000,000) | (19,000,000) | (20,000,000) | $ (3,000,000) |
Proceeds from equity method investments |  | 1,800,000 | 300,000 |  |  |
Prepaid expenses and other current assets |  | 307,000,000 |  | 256,000,000 |  |
Other non-current assets |  | 245,000,000 |  | 305,000,000 |  |
Loans receivable |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Loans and other receivables carried at amortized cost |  | 27,000,000 |  | 27,000,000 |  |
Cerfe Labs, Inc. | Loans receivable |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Loans and other receivables carried at amortized cost |  | 3,200,000 |  | 3,200,000 |  |
Ampere | Loans receivable |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Other non-current assets |  | 34,200,000 |  | 33,800,000 |  |
Related Parties |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Revenue |  | 328,000,000 | 124,000,000 |  |  |
Operating lease, lease income, lease payments |  | 200,000 | 400,000 |  |  |
Accounts receivable, net |  | 401,000,000 |  | 279,000,000 |  |
Other current liabilities (including payables to related parties of $10 and $11 as of June 30, 2025 and March 31, 2025, respectively) |  | 10,000,000 |  | 11,000,000 |  |
Contract liabilities |  | 104,000,000 |  | 105,000,000 |  |
Related Parties | Arduino | Loans receivable |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Other non-current assets |  | 16,800,000 |  | 16,600,000 |  |
Service Share Arrangement | Related Parties |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Revenue |  | 201,000,000 | 122,600,000 |  |  |
Operating expenses |  | 13,900,000 | 16,200,000 |  |  |
Net receivable |  | 355,900,000 |  | 284,600,000 |  |
Accounts receivable, net |  | 365,600,000 |  | 294,500,000 |  |
Other current liabilities (including payables to related parties of $10 and $11 as of June 30, 2025 and March 31, 2025, respectively) |  | 9,700,000 |  | 9,900,000 |  |
Contract liabilities |  | 103,400,000 |  | 104,200,000 |  |
Additional (reversal of) provision |  | 0 | (16,000,000) |  |  |
Allowance for current expected credit losses |  | (16,000,000) |  | (16,000,000) |  |
Common Control in SoftBank | Related Parties |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Revenue |  | 126,100,000 | 0 |  |  |
Accounts receivable, net |  | 45,000,000 |  | 0 |  |
Contract liabilities |  | 0 |  | 0 |  |
Contract assets |  | 226,600,000 |  | 145,500,000 |  |
Other Equity Investments | Related Parties |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Revenue |  | 600,000 | 1,400,000 |  |  |
Accounts receivable, net |  | 6,000,000 |  | 700,000 |  |
Contract liabilities |  | 500,000 |  | 700,000 |  |
Contract assets |  | 500,000 |  | 6,300,000 |  |
Linaro Agreement | Related Parties |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Other current liabilities (including payables to related parties of $10 and $11 as of June 30, 2025 and March 31, 2025, respectively) |  | 300,000 |  | 700,000 |  |
Subscription costs incurred |  | 2,300,000 | $ 2,400,000 |  |  |
Amounts of transaction | $ 4,000,000 |  |  |  |  |
Related party transaction, term | 5 years |  |  |  |  |
Prepaid expenses and other current assets |  | $ 2,400,000 |  | $ 2,400,000 |  |
Acetone Limited |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Ownership percentage |  |  |  |  |  | 10.00%
Arm China | Acetone Limited |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Ownership percentage |  |  |  |  |  | 48.20%

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