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Investments & Fair Value Measurements - Investment Portfolio (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Dec. 30, 2022 | Mar. 31, 2023 | Sep. 30, 2022
Cash and cash equivalents: |  |  |
Cash |  | $ 688,443 | $ 620,128
Cash and cash equivalents |  | 688,443 | 620,127
Cash equivalents, unrealized Loss |  |  | 1
Short-term investments: |  |  |
Total |  | 308,063 | 426,149
Long-term investments: |  |  |
Cost |  | 102,460 | 106,746
Unrealized Gains |  | 269 | 4
Unrealized Losses |  | 1,932 | 4,236
Total |  | 100,797 | 102,514
Investment at Cost |  | 918,629 | 917,841
Investment unrealized gain |  | 285 | 13
Investment unrealized loss |  | (3,281) | (6,000)
Cash Cash Equivalents And Investments Total |  | 915,633 | 911,854
Equity Method Investments |  | $ 5,200 | $ 5,900
Derivative Asset, Statement of Financial Position [Extensible Enumeration] |  | Prepaid expenses and other current assets |
Derivative Liability, Statement of Financial Position [Extensible Enumeration] |  | Accrued liabilities | Accrued liabilities
Equity method investment income (loss) |  | $ 1,700 |
Derivative Financial Instruments, Liabilities |  |  |
Long-term investments: |  |  |
Derivative Financial Instruments, Unrealized Gain |  | 0 |
Derivative Financial Instruments, Unrealized Loss | $ (420) | (299) |
Derivative Liability |  | (299) | $ (420)
Derivative Financial Instruments, Liabilities, Amortized Cost Basis |  | 0 | 0
us-Derivative Financial Instruments, Liabilities, Noncurrent |  |  |
Long-term investments: |  |  |
Derivative Financial Instruments, Unrealized Gain | 0 |  |
Derivative Financial Instruments, Assets |  |  |
Long-term investments: |  |  |
Derivative Financial Instruments, Assets, Amortized Cost Basis |  | 0 |
Derivative Financial Instruments, Unrealized Gain | 0 | 641 |
Derivative Financial Instruments, Unrealized Loss | $ (4,882) | 0 |
Derivative Asset |  | 641 | (4,882)
Certificate of deposit |  |  |
Short-term investments: |  |  |
Cost |  | 13,145 | 23,033
Unrealized Gains |  | 2 | 8
Unrealized Losses |  | (41) | (47)
Total |  | 13,106 | 22,994
US Government Agencies Short-term Debt Securities [Member] |  |  |
Short-term investments: |  |  |
Cost |  | 1,450 | 3,412
Unrealized Gains |  | 0 | 0
Unrealized Losses |  | (31) | (21)
Total |  | 1,419 | 3,391
Government bonds |  |  |
Short-term investments: |  |  |
Cost |  | 46,417 | 57,417
Unrealized Gains |  | 1 | 0
Unrealized Losses |  | (879) | (705)
Total |  | 45,539 | 56,712
Long-term investments: |  |  |
Cost |  | 33,745 | 43,816
Unrealized Gains |  | 102 | 0
Unrealized Losses |  | 828 | 2,222
Total |  | 33,019 | 41,594
Commercial paper |  |  |
Short-term investments: |  |  |
Cost |  | 6,892 | 8,786
Unrealized Gains |  | 0 | 1
Unrealized Losses |  | (13) | (15)
Total |  | 6,879 | 8,772
Corporate bonds |  |  |
Short-term investments: |  |  |
Cost |  | 35,796 | 72,730
Unrealized Gains |  | 0 | 0
Unrealized Losses |  | (239) | (734)
Total |  | 35,557 | 71,996
Long-term investments: |  |  |
Cost |  | 35,005 | 29,684
Unrealized Gains |  | 40 | 4
Unrealized Losses |  | 857 | 1,349
Total |  | 34,188 | 28,339
Municipal debt securities |  |  |
Short-term investments: |  |  |
Cost |  | 24,026 | 25,589
Unrealized Gains |  | 13 | 0
Unrealized Losses |  | (146) | (241)
Total |  | 23,893 | 25,348
Long-term investments: |  |  |
Cost |  | 23,489 | 21,483
Unrealized Gains |  | 127 | 0
Unrealized Losses |  | 247 | 626
Total |  | 23,369 | 20,857
Short-Term Investments |  |  |
Short-term investments: |  |  |
Cost |  | 127,726 | 190,967
Unrealized Gains |  | 16 | 9
Unrealized Losses |  | (1,349) | (1,763)
Total |  | 126,393 | 189,213
Other Long-term Investments |  |  |
Long-term investments: |  |  |
Cost |  | 10,221 | 10,902
Unrealized Gains |  | 0 | 0
Unrealized Losses |  | 0 | 0
Total |  | 10,221 | 10,902
Estimated Fair Value |  | 5,000 | 5,000
U.S. agency securities |  |  |
Long-term investments: |  |  |
Cost |  |  | 861
Unrealized Gains |  |  | 0
Unrealized Losses |  |  | 39
Total |  |  | 822
Level 1 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | 688,443 | 609,800
Short-term investments: |  |  |
Estimated Fair Value |  | 41,598 | 52,833
Long-term investments: |  |  |
Estimated Fair Value |  | 32,132 | 38,055
Assets |  | 762,173 | 700,688
Derivative Asset |  | 0 |
Derivative Liability |  | 0 |
Level 1 | Certificate of deposit |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 1 | US Government Agencies Short-term Debt Securities [Member] |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 1 | Government bonds |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 41,598 | 52,833
Long-term investments: |  |  |
Estimated Fair Value |  | 32,132 | 38,055
Level 1 | Commercial paper |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 1 | Corporate bonds |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 1 | Municipal debt securities |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 1 | Other Long-term Investments |  |  |
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 1 | Investments Held In Supplemental Retirement Plan |  |  |
Long-term investments: |  |  |
Assets |  | 4,000 | 4,225
Financial liabilities carried at fair value |  | 4,000 | 4,225
Level 1 | U.S. agency securities |  |  |
Long-term investments: |  |  |
Estimated Fair Value |  |  | 0
Level 2 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | 0 | 10,327
Short-term investments: |  |  |
Estimated Fair Value |  | 84,795 | 136,380
Long-term investments: |  |  |
Estimated Fair Value |  | 58,444 | 53,557
Assets |  | 143,239 | 200,264
Derivative Asset |  | 641 | (4,882)
Derivative Liability |  | (299) | (420)
Level 2 | Certificate of deposit |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 13,106 | 22,994
Level 2 | US Government Agencies Short-term Debt Securities [Member] |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 1,419 | 3,391
Level 2 | Government bonds |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 3,941 | 3,879
Long-term investments: |  |  |
Estimated Fair Value |  | 887 | 3,539
Level 2 | Commercial paper |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 6,879 | 8,772
Level 2 | Corporate bonds |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 35,557 | 71,996
Long-term investments: |  |  |
Estimated Fair Value |  | 34,188 | 28,339
Level 2 | Municipal debt securities |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 23,893 | 25,348
Long-term investments: |  |  |
Estimated Fair Value |  | 23,369 | 20,857
Level 2 | Other Long-term Investments |  |  |
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 2 | Investments Held In Supplemental Retirement Plan |  |  |
Long-term investments: |  |  |
Assets |  | 0 |
Financial liabilities carried at fair value |  | 0 |
Level 2 | U.S. agency securities |  |  |
Long-term investments: |  |  |
Estimated Fair Value |  |  | 822
Level 3 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | 0 | 0
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Assets |  | 0 | 0
Derivative Asset |  | 0 |
Derivative Liability |  | 0 |
Level 3 | Certificate of deposit |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 3 | US Government Agencies Short-term Debt Securities [Member] |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 3 | Government bonds |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 3 | Commercial paper |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 3 | Corporate bonds |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 3 | Municipal debt securities |  |  |
Short-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 3 | Other Long-term Investments |  |  |
Long-term investments: |  |  |
Estimated Fair Value |  | 0 | 0
Level 3 | Investments Held In Supplemental Retirement Plan |  |  |
Long-term investments: |  |  |
Assets |  | 0 |
Financial liabilities carried at fair value |  | 0 |
Level 3 | U.S. agency securities |  |  |
Long-term investments: |  |  |
Estimated Fair Value |  |  | 0
Cash |  |  |
Cash and cash equivalents: |  |  |
Cash |  | 597,659 | 474,813
Cash and cash equivalents |  | 597,659 | 474,813
Cash | Level 1 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | 597,659 | 474,813
Cash | Level 2 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | 0 | 0
Cash | Level 3 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | 0 | 0
Money Market Funds |  |  |
Cash and cash equivalents: |  |  |
Cash |  | 90,784 | 134,987
Cash and cash equivalents |  | 90,784 | 134,987
Money Market Funds | Level 1 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | 90,784 | 134,987
Money Market Funds | Level 2 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | 0 | 0
Money Market Funds | Level 3 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  | $ 0 | 0
U.S. agency securities |  |  |
Cash and cash equivalents: |  |  |
Cash |  |  | 10,328
Cash and cash equivalents |  |  | 10,327
Cash equivalents, unrealized Loss |  |  | 1
U.S. agency securities | Level 1 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  |  | 0
U.S. agency securities | Level 2 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  |  | 10,327
U.S. agency securities | Level 3 |  |  |
Cash and cash equivalents: |  |  |
Estimated Fair Value |  |  | $ 0

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