Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions | Dec. 27, 2020 | Sep. 27, 2020 |
Assets: | | |
Total short-term investments | $ 235.5 | $ 281.2 |
Total Assets | 5,532.7 | 4,941.1 |
Liabilities: | | |
Financial Liabilities Fair Value Disclosure | 80.6 | 86.6 |
Cash and Cash Equivalents [Member] | | |
Assets: | | |
Cash and cash equivalents | 5,028.1 | 4,350.9 |
Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 169.6 | 216.3 |
Equity Securities, FV-NI | 65.9 | 64.9 |
Total short-term investments | 235.5 | 281.2 |
Prepaid Expenses and Other Current Assets [Member] | | |
Assets: | | |
Derivative assets, current | 24.7 | 15.6 |
Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 190.9 | 206.1 |
Other Long-Term Assets [Member] | | |
Assets: | | |
Derivative assets, Noncurrent | 53.5 | 87.3 |
Accrued Liabilities [Member] | | |
Liabilities: | | |
Derivative liabilities, Current | 13.2 | 7.3 |
Other Long-Term Liabilities [Member] | | |
Liabilities: | | |
Derivative liabilities, Noncurrent | 67.4 | 79.3 |
Auction Rate Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 5.7 | 5.7 |
Certificates of Deposit | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 1.6 | 1.6 |
Commercial Paper [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 71.8 | 66.8 |
Corporate Debt Securities [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 78.5 | 123.6 |
Corporate Debt Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 82.6 | 82.6 |
Foreign Government Obligations [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | | 8.5 |
Mortgage and Other Asset-backed Securities [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 16.7 | 15.8 |
Mortgage and Other Asset-backed Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 9.8 | 19.3 |
State and Local Government Obligations [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 1 | |
State and Local Government Obligations [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 2.6 | 3.6 |
U.S. Government Treasury Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 90.2 | 94.9 |
Fair Value, Inputs, Level 1 [Member] | | |
Assets: | | |
Total Assets | 5,198.8 | 4,514.3 |
Liabilities: | | |
Financial Liabilities Fair Value Disclosure | 0.8 | 2 |
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member] | | |
Assets: | | |
Cash and cash equivalents | 5,028.1 | 4,350.9 |
Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Equity Securities, FV-NI | 65.9 | 64.9 |
Total short-term investments | 65.9 | 64.9 |
Fair Value, Inputs, Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member] | | |
Assets: | | |
Derivative assets, current | 14.6 | 3.6 |
Fair Value, Inputs, Level 1 [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 90.2 | 94.9 |
Fair Value, Inputs, Level 1 [Member] | Other Long-Term Assets [Member] | | |
Assets: | | |
Derivative assets, Noncurrent | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Accrued Liabilities [Member] | | |
Liabilities: | | |
Derivative liabilities, Current | 0.8 | 1.9 |
Fair Value, Inputs, Level 1 [Member] | Other Long-Term Liabilities [Member] | | |
Liabilities: | | |
Derivative liabilities, Noncurrent | 0 | 0.1 |
Fair Value, Inputs, Level 1 [Member] | Auction Rate Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Certificates of Deposit | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Foreign Government Obligations [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | | 0 |
Fair Value, Inputs, Level 1 [Member] | Mortgage and Other Asset-backed Securities [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Mortgage and Other Asset-backed Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | State and Local Government Obligations [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | |
Fair Value, Inputs, Level 1 [Member] | State and Local Government Obligations [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | U.S. Government Treasury Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 90.2 | 94.9 |
Fair Value, Inputs, Level 2 [Member] | | |
Assets: | | |
Total Assets | 328.2 | 421.1 |
Liabilities: | | |
Financial Liabilities Fair Value Disclosure | 79.8 | 84.6 |
Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member] | | |
Assets: | | |
Cash and cash equivalents | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 169.6 | 216.3 |
Equity Securities, FV-NI | 0 | 0 |
Total short-term investments | 169.6 | 216.3 |
Fair Value, Inputs, Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | | |
Assets: | | |
Derivative assets, current | 10.1 | 12 |
Fair Value, Inputs, Level 2 [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 95 | 105.5 |
Fair Value, Inputs, Level 2 [Member] | Other Long-Term Assets [Member] | | |
Assets: | | |
Derivative assets, Noncurrent | 53.5 | 87.3 |
Fair Value, Inputs, Level 2 [Member] | Accrued Liabilities [Member] | | |
Liabilities: | | |
Derivative liabilities, Current | 12.4 | 5.4 |
Fair Value, Inputs, Level 2 [Member] | Other Long-Term Liabilities [Member] | | |
Liabilities: | | |
Derivative liabilities, Noncurrent | 67.4 | 79.2 |
Fair Value, Inputs, Level 2 [Member] | Auction Rate Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | Certificates of Deposit | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 1.6 | 1.6 |
Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 71.8 | 66.8 |
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 78.5 | 123.6 |
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 82.6 | 82.6 |
Fair Value, Inputs, Level 2 [Member] | Foreign Government Obligations [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | | 8.5 |
Fair Value, Inputs, Level 2 [Member] | Mortgage and Other Asset-backed Securities [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 16.7 | 15.8 |
Fair Value, Inputs, Level 2 [Member] | Mortgage and Other Asset-backed Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 9.8 | 19.3 |
Fair Value, Inputs, Level 2 [Member] | State and Local Government Obligations [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 1 | |
Fair Value, Inputs, Level 2 [Member] | State and Local Government Obligations [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 2.6 | 3.6 |
Fair Value, Inputs, Level 2 [Member] | U.S. Government Treasury Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | | |
Assets: | | |
Total Assets | 5.7 | 5.7 |
Liabilities: | | |
Financial Liabilities Fair Value Disclosure | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member] | | |
Assets: | | |
Cash and cash equivalents | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Equity Securities, FV-NI | 0 | 0 |
Total short-term investments | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member] | | |
Assets: | | |
Derivative assets, current | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 5.7 | 5.7 |
Fair Value, Inputs, Level 3 [Member] | Other Long-Term Assets [Member] | | |
Assets: | | |
Derivative assets, Noncurrent | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Accrued Liabilities [Member] | | |
Liabilities: | | |
Derivative liabilities, Current | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Other Long-Term Liabilities [Member] | | |
Liabilities: | | |
Derivative liabilities, Noncurrent | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Auction Rate Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 5.7 | 5.7 |
Fair Value, Inputs, Level 3 [Member] | Certificates of Deposit | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Commercial Paper [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Foreign Government Obligations [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | | 0 |
Fair Value, Inputs, Level 3 [Member] | Mortgage and Other Asset-backed Securities [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Mortgage and Other Asset-backed Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | State and Local Government Obligations [Member] | Short-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | |
Fair Value, Inputs, Level 3 [Member] | State and Local Government Obligations [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | U.S. Government Treasury Securities [Member] | Long-term Investments [Member] | | |
Assets: | | |
Debt Securities, Available-for-sale | $ 0 | $ 0 |