Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Sep. 28, 2014	Sep. 29, 2013
Assets [Abstract]
Total short-term investments	$ 135.4	$ 658.1
Long-term investments: Available-for-sale securities	318.4	58.3
Total	2,208.9	3,316.0
Liabilities [Abstract]
Total		4.0
Cash and Cash Equivalents [Member]
Assets [Abstract]
Cash and cash equivalents	1,708.4	2,575.7
Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	63.2	591.5
Short-term investments: Trading securities	72.2	66.6
Total short-term investments	135.4	658.1
Prepaid Expenses and Other Current Assets [Member]
Assets [Abstract]
Prepaid expenses and other current assets: Derivative assets	28.7	12.5
Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	318.4	58.3
Other Assets [Member]
Assets [Abstract]
Other Assets: Derivative assets	18.0	11.4
Accrued Liabilities [Member]
Liabilities [Abstract]
Accrued liabilities: Derivative liabilities	2.4	3.5
Other Long-term Liabilities [Member]
Liabilities [Abstract]
Other long-term liabilities: Derivative liabilities		0.5
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Total	1,887.2	2,995.2
Liabilities [Abstract]
Total		0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Cash and Cash Equivalents [Member]
Assets [Abstract]
Cash and cash equivalents	1,708.4	2,575.7
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	10.9	352.9
Short-term investments: Trading securities	72.2	66.6
Total short-term investments	83.1	419.5
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Prepaid Expenses and Other Current Assets [Member]
Assets [Abstract]
Prepaid expenses and other current assets: Derivative assets	0.9	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	94.8	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Other Assets [Member]
Assets [Abstract]
Other Assets: Derivative assets	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Accrued Liabilities [Member]
Liabilities [Abstract]
Accrued liabilities: Derivative liabilities	0.4	0
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Other Long-term Liabilities [Member]
Liabilities [Abstract]
Other long-term liabilities: Derivative liabilities		0
Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Total	307.9	307.4
Liabilities [Abstract]
Total		4.0
Significant Other Observable Inputs (Level 2) [Member] | Cash and Cash Equivalents [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	52.3	238.6
Short-term investments: Trading securities	0	0
Total short-term investments	52.3	238.6
Significant Other Observable Inputs (Level 2) [Member] | Prepaid Expenses and Other Current Assets [Member]
Assets [Abstract]
Prepaid expenses and other current assets: Derivative assets	27.8	12.5
Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	209.8	44.9
Significant Other Observable Inputs (Level 2) [Member] | Other Assets [Member]
Assets [Abstract]
Other Assets: Derivative assets	18.0	11.4
Significant Other Observable Inputs (Level 2) [Member] | Accrued Liabilities [Member]
Liabilities [Abstract]
Accrued liabilities: Derivative liabilities	2.0	3.5
Significant Other Observable Inputs (Level 2) [Member] | Other Long-term Liabilities [Member]
Liabilities [Abstract]
Other long-term liabilities: Derivative liabilities		0.5
Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Total	13.8	13.4
Liabilities [Abstract]
Total		0
Significant Unobservable Inputs (Level 3) [Member] | Cash and Cash Equivalents [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0	0
Short-term investments: Trading securities	0	0
Total short-term investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Prepaid Expenses and Other Current Assets [Member]
Assets [Abstract]
Prepaid expenses and other current assets: Derivative assets	0	0
Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	13.8	13.4
Significant Unobservable Inputs (Level 3) [Member] | Other Assets [Member]
Assets [Abstract]
Other Assets: Derivative assets	0	0
Significant Unobservable Inputs (Level 3) [Member] | Accrued Liabilities [Member]
Liabilities [Abstract]
Accrued liabilities: Derivative liabilities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Other Long-term Liabilities [Member]
Liabilities [Abstract]
Other long-term liabilities: Derivative liabilities		0
Agency Obligations [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities		20.0
Agency Obligations [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	8.9	8.1
Agency Obligations [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities		0
Agency Obligations [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0	0
Agency Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities		20.0
Agency Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	8.9	8.1
Agency Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities		0
Agency Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0	0
Commercial Paper [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities		127.0
Commercial Paper [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities		0
Commercial Paper [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities		127.0
Commercial Paper [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities		0
Corporate Debt Securities [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	4.9	57.5
Corporate Debt Securities [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	130.9	36.8
Corporate Debt Securities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0	0
Corporate Debt Securities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0	0
Corporate Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	4.9	57.5
Corporate Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	130.9	36.8
Corporate Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0	0
Corporate Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0	0
Auction Rate Securities [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	13.8	13.4
Auction Rate Securities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0	0
Auction Rate Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0	0
Auction Rate Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	13.8	13.4
Foreign Government Obligations [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	33.7
Foreign Government Obligations [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	17.4
Foreign Government Obligations [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0
Foreign Government Obligations [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0
Foreign Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	33.7
Foreign Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	17.4
Foreign Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0
Foreign Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0
US Government Treasury Securities [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	10.9	352.9
US Government Treasury Securities [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	94.8
US Government Treasury Securities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	10.9	352.9
US Government Treasury Securities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	94.8
US Government Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0	0
US Government Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0
US Government Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0	0
US Government Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0
State and Local Government Obligations [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	12.7
State and Local Government Obligations [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	6.7
State and Local Government Obligations [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0
State and Local Government Obligations [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0
State and Local Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	12.7
State and Local Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	6.7
State and Local Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0
State and Local Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0
Certificates of Deposit [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	1.0	34.1
Certificates of Deposit [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0	0
Certificates of Deposit [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	1.0	34.1
Certificates of Deposit [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets [Abstract]
Short-term investments: Available-for-sale securities	0	0
Mortgage and Asset-backed Securities [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	45.9
Mortgage and Asset-backed Securities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	0
Mortgage and Asset-backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	45.9
Mortgage and Asset-backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets [Abstract]
Long-term investments: Available-for-sale securities	$ 0