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Related Party Transactions (Details) - USD ($) | 1 Months Ended | 3 Months Ended | 6 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Feb. 28, 2023 | Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Jun. 30, 2025 | Mar. 31, 2025 | Jun. 30, 2024 | Mar. 31, 2024 | Mar. 31, 2023
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Total revenue |  | $ 1,135,000,000 | $ 844,000,000 | $ 2,188,000,000 | $ 1,783,000,000 |  |  |  |  |
Operating expenses |  | 943,000,000 | 748,000,000 | 1,852,000,000 | 1,472,000,000 |  |  |  |  |
Accounts receivable, net |  | 1,119,000,000 |  | 1,119,000,000 |  |  | $ 1,107,000,000 |  |  |
Other current liabilities |  | 414,000,000 |  | 414,000,000 |  |  | 426,000,000 |  |  |
Contract liabilities |  | 296,000,000 |  | 296,000,000 |  |  | 209,000,000 |  |  |
Additional (reversal of) provision |  | 0 | 0 | (1,000,000) | 16,000,000 |  |  |  |  |
Accounts receivable, allowance |  | 19,000,000 | 19,000,000 | 19,000,000 | 19,000,000 | $ 19,000,000 | 20,000,000 | $ 19,000,000 | $ 3,000,000 |
Proceeds from equity method investments |  | 2,600,000 | 1,000,000 | 4,400,000 | 1,300,000 |  |  |  |  |
Total prepaid expenses and other current assets |  | 346,000,000 |  | 346,000,000 |  |  | 256,000,000 |  |  |
Other non-current assets |  | 249,000,000 |  | 249,000,000 |  |  | 305,000,000 |  |  |
Loan receivable |  | 3,000,000 |  | 3,000,000 |  |  | 20,000,000 |  |  |
Loans receivable |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Loans and other receivables carried at amortized cost |  | 27,000,000 |  | 27,000,000 |  |  | 27,000,000 |  |  |
Arduino |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Loans and other receivables carried at amortized cost |  | 16,900,000 |  | 16,900,000 |  |  | 16,600,000 |  |  |
Cerfe Labs, Inc. | Loans receivable |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Loans and other receivables carried at amortized cost |  | 3,200,000 |  | 3,200,000 |  |  | 3,200,000 |  |  |
Ampere | Loans receivable |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Total prepaid expenses and other current assets |  | 34,500,000 |  | 34,500,000 |  |  |  |  |  |
Other non-current assets |  |  |  |  |  |  | 33,800,000 |  |  |
Related Parties |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Total revenue |  | 422,000,000 | 192,000,000 | 750,000,000 | 316,000,000 |  |  |  |  |
Operating lease, lease income, lease payments |  | 300,000 | 300,000 | 500,000 | 700,000 |  |  |  |  |
Accounts receivable, net |  | 304,000,000 |  | 304,000,000 |  |  | 279,000,000 |  |  |
Other current liabilities |  | 6,000,000 |  | 6,000,000 |  |  | 11,000,000 |  |  |
Contract liabilities |  | 88,000,000 |  | 88,000,000 |  |  | 105,000,000 |  |  |
Related Parties | Arduino | Loans receivable |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Other non-current assets |  | 16,900,000 |  | 16,900,000 |  |  | 16,600,000 |  |  |
Service Share Arrangement | Related Parties |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Total revenue |  | 243,100,000 | 147,700,000 | 444,100,000 | 270,300,000 |  |  |  |  |
Operating expenses |  | 14,600,000 | 15,200,000 | 28,500,000 | 31,400,000 |  |  |  |  |
Net receivable |  | 315,000,000 |  | 315,000,000 |  |  | 284,600,000 |  |  |
Accounts receivable, net |  | 320,500,000 |  | 320,500,000 |  |  | 294,500,000 |  |  |
Other current liabilities |  | 5,500,000 |  | 5,500,000 |  |  | 9,900,000 |  |  |
Contract liabilities |  | 87,700,000 |  | 87,700,000 |  |  | 104,200,000 |  |  |
Additional (reversal of) provision |  | 0 | 0 | 0 | 16,000,000.0 |  |  |  |  |
Accounts receivable, allowance |  | 16,000,000 |  | 16,000,000 |  |  | 16,000,000 |  |  |
Common Control in SoftBank | Related Parties |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Total revenue |  | 177,900,000 | 43,200,000 | 304,000,000 | 43,200,000 |  |  |  |  |
Accounts receivable, net |  | 0 |  | 0 |  |  | 0 |  |  |
Contract liabilities |  | 0 |  | 0 |  |  | 0 |  |  |
Contract assets |  | 351,500,000 |  | 351,500,000 |  |  | 145,500,000 |  |  |
Other Equity Investments | Related Parties |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Total revenue |  | 800,000 | 600,000 | 1,400,000 | 2,000,000 |  |  |  |  |
Accounts receivable, net |  | 0 |  | 0 |  |  | 700,000 |  |  |
Contract liabilities |  | 300,000 |  | 300,000 |  |  | 700,000 |  |  |
Contract assets |  | 1,000,000 |  | 1,000,000 |  |  | 6,300,000 |  |  |
Linaro Agreement | Related Parties |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |
Other current liabilities |  | 300,000 |  | 300,000 |  |  | 700,000 |  |  |
Subscription costs incurred |  | 2,200,000 | $ 3,000,000 | 4,500,000 | $ 5,400,000 |  |  |  |  |
Amounts of transaction | $ 4,000,000 |  |  |  |  |  |  |  |  |
Related party transaction, term | 5 years |  |  |  |  |  |  |  |  |
Total prepaid expenses and other current assets |  | $ 2,400,000 |  | $ 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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