Condensed Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Condensed Consolidated Statements of Comprehensive Income [Abstract]
Tax on (loss) gain on derivative instruments	$ 16.2	$ (1.3)	$ 39.3	$ (13.1)
Tax on reclassifications on derivative instruments	(13.8)	(6.1)	(21.8)	(17.0)
Tax on foreign currency adjustments	(8.0)	(9.3)	(1.5)	(6.0)
Tax on benefit plans	$ (0.1)	$ 0.1	$ (0.2)	$ (1.4)

Tax effect on the accumulated change in the value of either the projected benefit obligation or plan assets resulting from experience different from that assumed or from a change in an actuarial assumption that has not been recognized in net periodic benefit cost.

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Tax effect of the adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label.

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- Definition

Tax effect on reclassification adjustment for accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges included in accumulated comprehensive income that was realized in net income during the period.

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- Definition

Tax effect on the change in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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