BUSINESS SEGMENT AND OTHER OPERATIONS DATA, RECONCILIATION OF SEGMENT INCOME TO CONSOLIDATED (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Segment Reporting Information [Line Items]
Utility	$ 106,764		$ 138,149		$ 524,161		$ 862,073
Nonutility	318,357		510,020		1,156,292		1,476,235
Total operating revenues	425,121		648,169		1,680,453		2,338,308
Depreciation and amortization	10,687		8,514		30,726		25,445
Investment Income, Interest	253	[1]	311	[1]	770	[1]	874	[1]
Interest expense, net of capitalized interest	4,834		4,744		15,266		15,085
Income tax provision (benefit)	(11,230)		6,197		15,901		48,662
Equity in earnings of affiliates	2,644		2,957		8,316		9,484
Net Financial Earnings (Loss)	4,130		9,699		123,564		105,858
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	46,971		38,835		158,361		97,921
Reportable Segment [Member]
Segment Reporting Information [Line Items]
Total operating revenues	413,375		638,890		1,654,689		2,366,663
Depreciation and amortization	10,509		8,323		30,246		24,843
Investment Income, Interest	500	[1]	530	[1]	1,519	[1]	1,530	[1]
Interest expense, net of capitalized interest	4,774		4,640		14,476		14,695
Income tax provision (benefit)	(12,284)		5,615		15,358		49,137
Equity in earnings of affiliates	3,547		3,891		11,129		11,871
Net Financial Earnings (Loss)	2,597		8,298		122,756		104,945
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	46,862		37,823		157,793		94,946
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	8,860		8,192		26,241		24,650
Investment Income, Interest	223	[1]	304	[1]	683	[1]	844	[1]
Interest expense, net of capitalized interest	3,717		3,630		11,167		11,454
Income tax provision (benefit)	1,114		3,283		43,726		44,162
Net Financial Earnings (Loss)	7,545		5,979		78,455		74,375
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	33,405		30,783		82,550		77,969
Natural Gas Distribution [Member] | External Customers [Member]
Segment Reporting Information [Line Items]
Utility	106,764		138,149		524,161		862,073
Natural Gas Distribution [Member] | Intercompany [Member]
Segment Reporting Information [Line Items]
Utility	0		0		0		0
Energy Services [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	16		15		48		46
Investment Income, Interest	10	[1]	1	[1]	36	[1]	9	[1]
Interest expense, net of capitalized interest	214		193		729		792
Income tax provision (benefit)	(11,511)		1,949		(2,108)		8,632
Net Financial Earnings (Loss)	(5,425)		213		18,061		19,381
Energy Services [Member] | External Customers [Member]
Segment Reporting Information [Line Items]
Nonutility	306,273		498,834		1,126,435		1,449,252
Energy Services [Member] | Intercompany [Member]
Segment Reporting Information [Line Items]
Nonutility	(32)		1,579		2,816		55,010
Energy Holdings [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	1		1		4		4
Investment Income, Interest	267	[1]	225	[1]	800	[1]	677	[1]
Interest expense, net of capitalized interest	653		803		2,050		2,428
Income tax provision (benefit)	1,126		1,281		3,750		3,951
Equity in earnings of affiliates	3,547		3,891		11,129		11,871
Net Financial Earnings (Loss)	1,634		1,847		5,438		5,705
Clean Energy Ventures [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	1,632		115		3,953		143
Interest expense, net of capitalized interest	190		14		530		21
Income tax provision (benefit)	(3,013)		(898)		(30,010)		(7,608)
Net Financial Earnings (Loss)	(1,157)		259		20,802		5,484
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	13,457		7,040		75,243		16,977
Clean Energy Ventures [Member] | External Customers [Member]
Segment Reporting Information [Line Items]
Nonutility	370		328		1,277		328
Retail and Other [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	178		191		480		602
Investment Income, Interest	1	[1]	1	[1]	2	[1]	2	[1]
Interest expense, net of capitalized interest	60		104		790		390
Income tax provision (benefit)	1,056		605		685		(439)
Net Financial Earnings (Loss)	1,549		1,401		860		913
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	109		1,012		568		2,975
Retail and Other [Member] | External Customers [Member]
Segment Reporting Information [Line Items]
Nonutility	11,714		10,859		28,580		26,655
Retail and Other [Member] | Intercompany [Member]
Segment Reporting Information [Line Items]
Nonutility	278		92		720		248
Business Intersegment, Eliminations [Member]
Segment Reporting Information [Line Items]
Nonutility	(246)		(1,672)		(3,536)		(55,258)
Depreciation and amortization	0		0		0		0
Investment Income, Interest	(248)	[1]	(220)	[1]	(751)	[1]	(658)	[1]
Income tax provision (benefit)	(2)		(23)		(142)		(36)
Equity in earnings of affiliates	(903)		(934)		(2,813)		(2,387)
Net Financial Earnings (Loss)	$ (16)		$ 0		$ (52)		$ 0

[1] Included in other income in the Unaudited Condensed Consolidated Statements of Operations.