Income Taxes (Tables)

12 Months Ended

Sep. 30, 2013

Income Tax Disclosure [Abstract]

Provisions for income taxes

The provisions for income taxes consist of the following:

	2013			2012			2011
Current expense (benefit):
Federal	$	21,807		$	(909	)	$	10,447
State	11,824			2,735			2,227
Total current expense	33,631			1,826			12,674
Deferred expense:
Federal	33,349			48,336			48,967
State	2,274			5,257			2,207
Investment tax credit amortization	(342		)	(346		)	(351		)
Total income tax expense	$	68,912		$	55,073		$	63,497

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:

	2013		2012		2011
U.S. federal statutory tax rate	35.0	%	35.0	%	35.0	%
Difference in tax rate due to:
State income taxes, net of federal	5.4		4.1		1.6
Other, net	(0.1	)	(0.6	)	1.0
Effective tax rate	40.3	%	38.5	%	37.6	%

Deferred tax liabilities (assets)

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

	2013			2012
Excess book basis over tax basis of property, plant and equipment	$	362,259		$	330,937
Goodwill	31,516			26,998
Regulatory assets	101,622			140,416
Other	949			601
Gross deferred tax liabilities	496,346			498,952
Pension plan liabilities	(35,996		)	(72,652		)
Allowance for doubtful accounts	(2,290		)	(1,489		)
Deferred investment tax credits	(1,772		)	(1,914		)
Employee-related expenses	(5,850		)	(4,859		)
Regulatory liabilities	(15,472		)	(11,761		)
Environmental liabilities	(7,002		)	(7,195		)
Derivative financial instruments	(3,397		)	(16,264		)
Other	(1,922		)	(12,202		)
Gross deferred tax assets	(73,701		)	(128,336		)
Net deferred tax liabilities	$	422,645		$	370,616

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, 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
Additions for tax positions of prior years	39
Balance at September 30, 2013	$	1,087