Business Segment and Geographic Information (Business Segment Information) (Details) (USD $) In Millions	3 Months Ended	9 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment and Consolidated Totals	$ 2,577.8	$ 2,252.3	$ 7,470.8	$ 6,674.8
Net loss on Airgas transaction		(37.9)	(48.5)	(61.3)
Customer bankruptcy		1.8		1.8
Pension settlement	0	(6.3)	0	(6.3)
Operating Income	416.8	336.4	1,196.9	1,022.0
Segment Total [Member]
Operating Income	414.4	379.7	1,239.6	1,086.2
Merchant Gases [Member]
Sales to External Customers	1,027.2	915.0	3,027.8	2,770.3
Operating Income	182.0	176.4	567.4	544.1
Tonnage Gases [Member]
Sales to External Customers	868.7	724.5	2,433.9	2,179.1
Operating Income	114.8	119.8	351.4	327.2
Electronics and Performance Materials [Member]
Sales to External Customers	602.4	496.9	1,704.3	1,381.5
Operating Income	109.0	62.4	269.5	167.8
Equipment and Energy [Member]
Sales to External Customers	79.5	115.9	304.8	343.9
Operating Income	8.6	21.1	51.3	47.1
Other [Member]
Operating Income	$ 2.4	$ (0.9)	$ 5.8	$ 1.6

The amount of net gain (loss) recognized in net periodic benefit cost as a result of an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include (a) making lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and (b) purchasing nonparticipating annuity contracts to cover vested benefits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Number 88
-Name Statement of Financial Accounting Standard (FAS)
-Paragraph 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(7)
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph h
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 15
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6412315&loc=d3e8001-114927

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details