Subsequent Event (Details) (Adoption of Plan Amendments [Member])	3 Months Ended
Dec. 31, 2011
Adoption of Plan Amendments [Member]
Subsequent Event [Line Items]
Subsequent event, description	Effective January 1, 2012, the traditional defined benefit plan formula will be transitioned to a cash balance formula, and no further benefits will be accrued under the defined benefit plan formula.
Percentage of employee's eligible cash compensation provided as annual retirement benefit, under the cash balance formula (in hundredths)	5.00%
Maturity of U.S. Treasury Note on which interest is based (in years)	10Y

Describes the event or transaction that occurred between the balance sheet date and the date the financial statements are issued or available to be issued.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 855

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 165

-Paragraph 13

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration