The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph g

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 (g)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Retirement Benefits (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Sep. 30, 2011
Defined Benefit Plan Disclosure [Line Items]
Cash contributions to funded plans and benefit payments under unfunded plans	$ 23.4	$ 221.4	$ 241.0
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for 2012	40
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for 2012	$ 60