INCOME TAXES Income Tax Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Income Tax Examination [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Statutory income tax expense	$ 48,638	$ 63,753	$ 13,516
State income taxes	3,435	4,626	2,763
Depreciation and cost of removal	(2,558)	(1,986)	(2,191)
Investment tax credits	(13,150)	(769)	(322)
Basis adjustment of solar assets due to ITC	2,266	91	0
Fin 48 (ASC 740) and other interest accrued/(released)	0	0	(1,272)
Other	(966)	(1,023)	(1,118)
Income tax provision (benefit)	37,665	64,692	11,376
Effective income tax rate	27.10%	35.50%	29.50%
Current
Federal	14,566	(7,343)	26,860
State	6,618	(981)	7,603
Deferred
Federal	30,932	65,258	(17,713)
State	(1,301)	8,527	(5,052)
Investment tax credits	(13,150)	(769)	(322)
Income tax provision (benefit)	$ 37,665	$ 64,692	$ 11,376