Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012
Assets:
Cash and cash equivalents	$ 1,430.8	$ 1,188.6
Short-term investments: Available-for-sale securities	551.8	790.8
Short-term investments: Trading securities	61.7	57.6
Total short-term investments	613.5	848.4
Short term derivatives	68.6	9.5
Long-term investments	45.5	116.0
Long-term derivatives	12.9
Total	2,171.3	2,162.5
Liabilities:
Short-term derivatives	3.0	18.9
Long-term derivatives		3.0
Total derivatives		21.9
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Cash and cash equivalents	1,430.8	1,188.6
Short-term investments: Available-for-sale securities	311.9	459.7
Short-term investments: Trading securities	61.7	57.6
Total short-term investments	373.6	517.3
Short term derivatives	0	0
Long-term investments	0	0
Long-term derivatives	0
Total	1,804.4	1,705.9
Liabilities:
Short-term derivatives	0	0
Long-term derivatives		0
Total derivatives		0
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Cash and cash equivalents	0	0
Short-term investments: Available-for-sale securities	239.9	331.1
Short-term investments: Trading securities	0	0
Total short-term investments	239.9	331.1
Short term derivatives	68.6	9.5
Long-term investments	31.7	97.4
Long-term derivatives	12.9
Total	353.1	438.0
Liabilities:
Short-term derivatives	3.0	18.9
Long-term derivatives		3.0
Total derivatives		21.9
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Cash and cash equivalents	0	0
Short-term investments: Available-for-sale securities	0	0
Short-term investments: Trading securities	0	0
Total short-term investments	0	0
Short term derivatives	0	0
Long-term investments	13.8	18.6
Long-term derivatives	0
Total	13.8	18.6
Liabilities:
Short-term derivatives	0	0
Long-term derivatives		0
Total derivatives		0
Agency Obligations [Member]
Assets:
Short-term investments: Available-for-sale securities	10.0	80.0
Long-term investments	4.0	14.0
Agency Obligations [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Long-term investments	0	0
Agency Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Short-term investments: Available-for-sale securities	10.0	80.0
Long-term investments	4.0	14.0
Agency Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Long-term investments	0	0
Commercial Paper [Member]
Assets:
Short-term investments: Available-for-sale securities	123.9	103.9
Commercial Paper [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Commercial Paper [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Short-term investments: Available-for-sale securities	123.9	103.9
Commercial Paper [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Corporate Debt Securities [Member]
Assets:
Short-term investments: Available-for-sale securities	71.9	84.3
Long-term investments	27.7	61.3
Corporate Debt Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Long-term investments	0	0
Corporate Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Short-term investments: Available-for-sale securities	71.9	84.3
Long-term investments	27.7	61.3
Corporate Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Long-term investments	0	0
Government Treasury Securities [Member]
Assets:
Short-term investments: Available-for-sale securities	311.9	459.7
Government Treasury Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Short-term investments: Available-for-sale securities	311.9	459.7
Government Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Government Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Auction Rate Securities [Member]
Assets:
Long-term investments	13.8	18.6
Auction Rate Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Long-term investments	0	0
Auction Rate Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Long-term investments	0	0
Auction Rate Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Long-term investments	13.8	18.6
Certificates Of Deposit [Member]
Assets:
Short-term investments: Available-for-sale securities	34.1	62.9
Long-term investments		22.1
Certificates Of Deposit [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Long-term investments		0
Certificates Of Deposit [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Short-term investments: Available-for-sale securities	34.1	62.9
Long-term investments		22.1
Certificates Of Deposit [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Short-term investments: Available-for-sale securities	0	0
Long-term investments		$ 0