Fair Value Measurements (Schedule of Fair Value of Assets and Liabilities) (Details) (USD $) In Millions	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010
Other investments				$ 1.1
Total Assets at Fair Value	72.2			218.0
Other liabilities	50.8			42.0
Total Liabilities at Fair Value	101.4			96.2
Interest Rate Swaps Contracts [Member]
Derivative assets	29.1			39.7
Derivative liabilities	3.1			3.7
Interest Rate Swaps Contracts [Member] | Fair Value [Member]
Derivative assets	29.1			39.7
Derivative liabilities	3.1			3.7
Interest Rate Swaps Contracts [Member] | Level 1 [Member]
Derivative assets
Derivative liabilities
Interest Rate Swaps Contracts [Member] | Level 2 [Member]
Derivative assets	29.1			39.7
Derivative liabilities	3.1			3.7
Interest Rate Swaps Contracts [Member] | Level 3 [Member]
Derivative assets
Derivative liabilities
Foreign Exchange Contracts [Member]
Derivative assets	43.1			74.7
Derivative liabilities	47.5			50.5
Foreign Exchange Contracts [Member] | Fair Value [Member]
Derivative assets	43.1			74.7
Derivative liabilities	47.5			50.5
Foreign Exchange Contracts [Member] | Level 1 [Member]
Derivative assets
Derivative liabilities
Foreign Exchange Contracts [Member] | Level 2 [Member]
Derivative assets	43.1			74.7
Derivative liabilities	47.5			50.5
Foreign Exchange Contracts [Member] | Level 3 [Member]
Derivative assets
Derivative liabilities
Fair Value [Member]
Other investments				1.1
Other liabilities	50.8			42.0
Fair Value [Member] | Airgas Investment [Member]
Available-for-sale securities				102.5
Airgas Investment [Member] | Level 1 [Member]
Available-for-sale securities				102.5
Level 1 [Member]
Other investments				1.1
Total Assets at Fair Value				103.6
Other liabilities
Total Liabilities at Fair Value
Airgas Investment [Member] | Level 2 [Member]
Available-for-sale securities
Level 2 [Member]
Other investments
Total Assets at Fair Value	72.2			114.4
Other liabilities
Total Liabilities at Fair Value	50.6			54.2
Airgas Investment [Member] | Level 3 [Member]
Available-for-sale securities
Level 3 [Member]
Other investments
Total Assets at Fair Value
Other liabilities	50.8	51.4	48.6	42.0
Total Liabilities at Fair Value	50.8			42.0
Airgas Investment [Member]
Available-for-sale securities				$ 102.5