Summarized Financial Information Concerning the Company's Reportable Segments (Parenthetical) (Detail) (USD $) In Thousands	Sep. 30, 2011	Sep. 30, 2010
Segment Reporting Information [Line Items]
Including unconsolidated investments	$ 3,997	$ 2,040
Electricity
Segment Reporting Information [Line Items]
Including unconsolidated investments	2,287	2,040
Product
Segment Reporting Information [Line Items]
Including unconsolidated investments	$ 1,710

Total investments attributed to the reportable segment, excluding equity method investees. Includes debt and equity financial instruments (securities held-to-maturity, trading securities, and securities available-for-sale) as well as other investments.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 22

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8736-108599

Name:	us-gaap_SegmentReportingInformationInvestments
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant