Income Taxes (Tables)

12 Months Ended

Sep. 30, 2012

Income Tax Disclosure [Abstract]

Provisions for income taxes

The provisions for income taxes consist of the following:

	2012			2011			2010
Current expense (benefit):
Federal	$	(909	)	$	10,447		$	(8,577	)
State	2,735			2,227			1,848
Total current expense (benefit)	1,826			12,674			(6,729		)
Deferred expense	53,593			51,174			64,022
Investment tax credit amortization	(346		)	(351		)	(368		)
Total income tax expense	$	55,073		$	63,497		$	56,925

A reconciliation from the U.S. federal statutory tax rate to our effective tax rate

A reconciliation from the U.S. federal statutory tax rate to our effective tax rate is as follows:

	2012		2011		2010
U.S. federal statutory tax rate	35.0	%	35.0	%	35.0	%
Difference in tax rate due to:
State income taxes, net of federal	4.1		1.6		4.3
Other, net	(0.6	)	1.0		(0.6	)
Effective tax rate	38.5	%	37.6	%	38.7	%

Deferred tax liabilities (assets)

Deferred tax liabilities (assets) comprise the following at September 30:

	2012			2011
Excess book basis over tax basis of property, plant and equipment	$	330,937		$	293,457
Goodwill	26,998			22,446
Regulatory assets	140,416			124,669
Other	601			487
Gross deferred tax liabilities	498,952			441,059
Pension plan liabilities	(72,652		)	(62,818		)
Allowance for doubtful accounts	(1,489		)	(2,642		)
Deferred investment tax credits	(1,914		)	(2,057		)
Employee-related expenses	(4,859		)	(8,032		)
Regulatory liabilities	(11,761		)	(12,378		)
Environmental liabilities	(7,195		)	(7,749		)
Derivative financial instruments	(16,264		)	(11,931		)
Other	(12,202		)	(14,512		)
Gross deferred tax assets	(128,336		)	(122,119		)
Net deferred tax liabilities	$	370,616		$	318,940

Reconciliation of beginning and ending amount of unrecognized tax benefit

A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows:

Balance at September 30, 2009	$	634
Additions for tax positions of the current year	3,907
Additions for tax positions of prior years	9
Decreases for tax positions related to prior years	(25		)
Settlements with tax authorities	(331		)
Balance at September 30, 2010	4,194
Additions for tax positions of the current year	920
Settlements with tax authorities	(216		)
Balance at September 30, 2011	4,898
Additions for tax positions of prior years	81
Settlements with tax authorities	(3,931		)
Balance at September 30, 2012	$	1,048