| In millions, except per share items | Jun-25-23 | Dec-25-22 | Jun-26-22 | Mar-27-22 | Dec-26-21 | Sep-26-21 | Jun-27-21 | Mar-28-21 |
| | 8-K | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q |
| Operating activities: | | | | | | | | |
| Net loss | | | -200.9 | -380.9 | -422.5 | -408.5 | -522.5 | -413.8 |
| |
| Adjustments to reconcile net loss to cash used in operating activities: | | | | | | | | |
| Depreciation and amortization | | | 129.8 | 130.2 | 132.2 | 128.1 | 120.9 | 121.6 |
| Amortization of debt issuance costs and discount, net of non-cash capitalized interest | | | 20.1 | 19.6 | 23.7 | 28.5 | 32.8 | 35.2 |
| Stock-based compensation | | | 60.9 | 58.1 | 55.8 | 54.1 | 53.2 | 52.3 |
| Loss on disposal or impairment of long-lived assets, including loss on disposal portion of factory optimization and start-up costs | | | | 2.3 | 5.1 | 5.6 | 5.0 | 6.3 |
| Amortization of (premium) discount on investments, net | | | 6.1 | 6.5 | 6.9 | 7.1 | 6.9 | 6.1 |
| Realized gain on sale of investments | | | -0.6 | | 6.3 | | -0.4 | -19.1 |
| Foreign exchange gain on equity investment | | | | | | | -2.2 | -4.4 |
| Deferred income taxes | | | | 1.1 | -1.0 | 0.8 | 0.9 | 0.4 |
| Changes in operating assets and liabilities: | | | | | | | | |
| Accounts receivable, net | | | -54.3 | -38.3 | -28.1 | -45.4 | -23.5 | 35.1 |
| Inventories | | | -68.8 | -80.8 | -64.5 | -56.1 | -44.6 | -33.9 |
| Prepaid expenses and other assets | | | -0.4 | 4.9 | -23.9 | -24.1 | -20.0 | -31.1 |
| Accounts payable, trade | | | 29.2 | 5.8 | 14.6 | 19.2 | 21.7 | 30.1 |
| Accrued salaries and wages and other liabilities | | | -10.5 | 9.3 | -15.9 | -17.0 | 15.3 | 7.7 |
| Cash used in operating activities | | | -154.2 | -173.4 | -194.6 | -188.4 | -125.5 | -65.0 |
| |
| Investing activities: | | | | | | | | |
| Purchases of property and equipment | | | -644.9 | -712.0 | -714.6 | -716.3 | -570.5 | -462.2 |
| Purchases of patent and licensing rights | | | -5.7 | -6.5 | -6.6 | -5.7 | -5.9 | -5.6 |
| Proceeds from sale of property and equipment, including insurance proceeds | | | 3.1 | | 4.9 | 2.2 | 2.3 | 1.0 |
| Purchases of short-term investments | | | -475.0 | -541.1 | -419.0 | -422.0 | -475.0 | -750.3 |
| Proceeds from maturities of short-term investments | | | 242.3 | 228.2 | 267.6 | 347.7 | 428.3 | 453.7 |
| Proceeds from sale of short-term investments | | | 225.2 | 246.8 | 216.8 | 157.0 | 51.7 | 52.9 |
| Reimbursement of property and equipment purchases from long-term incentive agreement | | | 139.0 | 83.5 | | 50.8 | | |
| Cash used in investing activities | | | -391.0 | -487.1 | -482.3 | -464.6 | -448.6 | -674.2 |
| |
| Financing activities: | | | | | | | | |
| Proceeds from convertible notes | | | 738.5 | 0.2 | 490.9 | 514.3 | | 530.1 |
| Proceeds from issuance of common stock | | | 33.9 | 761.5 | 11.5 | | | |
| Commitment fees on long-term incentive agreement | | | -2.0 | | -1.5 | | -0.5 | |
| Cash provided by financing activities | | | 615.9 | 614.8 | 474.6 | 478.1 | 504.1 | 947.5 |