Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Summary of Tax-Related Interest Income

Tax-related interest income included in income tax expense in the consolidated statements of income is shown in the table below (in thousands):

	2013		2012		2011
Tax-related interest income	$	—	$	24	$	100

Summary of Income Tax Expense (Benefit)

Income tax expense (benefit) consists of the following (thousands of dollars):

Year Ended December 31,	2013		2012		2011
Current:
Federal	$	3,549	$	2,296	$	(265	)
State		5,107		5,744		2,122
		8,656		8,040		1,857
Deferred:
Federal		67,414		65,551		58,584
State		1,872		1,685		2,862
		69,286		67,236		61,446
Total income tax expense	$	77,942	$	75,276	$	63,303

Significant Components of Deferred Income Tax Expense (Benefit)

Deferred income tax expense (benefit) consists of the following significant components (thousands of dollars):

Year Ended December 31,	2013			2012			2011
Deferred federal and state:
Property-related items	$	62,737		$	64,249		$	51,710
Purchased gas cost adjustments		16,189			1,755			(92	)
Employee benefits		(2,769	)		564			11,766
All other deferred		(6,010	)		1,529			(1,070	)
Total deferred federal and state		70,147			68,097			62,314
Deferred ITC, net		(861	)		(861	)		(868	)
Total deferred income tax expense	$	69,286		$	67,236		$	61,446

Reconciliation of Federal Statutory Rate to Consolidated Effective Tax Rate

A reconciliation of the federal statutory rate to the consolidated effective tax rate for 2011, 2012, and 2013 (and the sources of these differences and the effect of each) are summarized as follows:

Year Ended December 31,	2013			2012			2011
Federal statutory income tax rate		35.0	%		35.0	%		35.0	%
Net state taxes		2.4			2.6			2.7
Property-related items		0.1			0.2			0.2
Effect of income tax settlements		—			—			(0.9	)
Tax credits		(0.4	)		(0.4	)		(0.6	)
Company owned life insurance		(2.1	)		(1.3	)		(0.1	)
All other differences		—			0.1			(0.1	)
Consolidated effective income tax rate		35.0	%		36.2	%		36.2	%

Deferred Tax Assets and Liabilities

Deferred tax assets and liabilities consist of the following (thousands of dollars):

December 31,	2013			2012
Deferred tax assets:
Deferred income taxes for future amortization of ITC	$	2,679		$	3,211
Employee benefits		25,591			27,097
Alternative minimum tax credit		19,739			18,467
Net operating losses and credits		15,113			36,206
Interest rate swap		9,893			11,164
Other		22,334			17,866
Valuation allowance		(200	)		(141	)
		95,149			113,870
Deferred tax liabilities:
Property-related items, including accelerated depreciation		694,024			652,380
Regulatory balancing accounts		18,688			2,498
Property-related items previously flowed through		836			1,729
Unamortized ITC		4,271			5,131
Debt-related costs		4,713			4,602
Other		15,898			16,626
		738,430			682,966
Net deferred tax liabilities	$	643,281		$	569,096
Current	$	(31,130	)	$	(47,088	)
Noncurrent		674,411			616,184
Net deferred tax liabilities	$	643,281		$	569,096