Short-Term Credit Arrangements and Borrowings (Details Textuals) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012 percent ratio banks
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 300
Revolving Credit Facilities with a Syndicate Number of Banks	20
Maximum Percentage of Commitment to Bank in Any Facility	8.50%
Maximum Total Funded Debt to Total Capitalization Ratio	65.00%
Total Funded Debt to Total Capitalization Ratio Denominator	100.00%
Total Funded Debt to Total Capitalization Ratio	52.00%
Amount of Delinquent Obligations Considered a Default Under Credit Agreements	$ 50

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant