Segment Information (Tables)

9 Months Ended

Sep. 30, 2013

Segment Reporting [Abstract]

Results from Continuing Operations by Reportable Segment

(Thousands of Dollars)	Regulated Electric		Regulated Natural Gas			All Other		Reconciling Eliminations			Consolidated Total
Three Months Ended Sept. 30, 2013
Operating revenues from external customers	$	216,545	$	14,266		$	249	$	—		$	231,060
Intersegment revenues	89		962			—		(1,051		)	—
Total revenues	$	216,634	$	15,228		$	249	$	(1,051	)	$	231,060
Net income (loss)	$	22,859	$	(1,726	)	$	880	$	—		$	22,013

(Thousands of Dollars)	Regulated Electric		Regulated Natural Gas			All Other		Reconciling Eliminations			Consolidated Total
Three Months Ended Sept. 30, 2012
Operating revenues from external customers	$	214,426	$	11,742		$	307	$	—		$	226,475
Intersegment revenues	82		321			—		(403		)	—
Total revenues	$	214,508	$	12,063		$	307	$	(403	)	$	226,475
Net income (loss)	$	21,743	$	(1,461	)	$	1,918	$	—		$	22,200

(Thousands of Dollars)	Regulated Electric		Regulated Natural Gas		All Other		Reconciling Eliminations			Consolidated Total
Nine Months Ended Sept. 30, 2013
Operating revenues from external customers	$	592,730	$	89,178	$	742	$	—		$	682,650
Intersegment revenues	250		1,549		—		(1,799		)	—
Total revenues	$	592,980	$	90,727	$	742	$	(1,799	)	$	682,650
Net income	$	46,530	$	4,100	$	1,612	$	—		$	52,242

(Thousands of Dollars)	Regulated Electric		Regulated Natural Gas		All Other		Reconciling Eliminations			Consolidated Total
Nine Months Ended Sept. 30, 2012
Operating revenues from external customers	$	575,532	$	68,064	$	851	$	—		$	644,447
Intersegment revenues	278		585		—		(863		)	—
Total revenues	$	575,810	$	68,649	$	851	$	(863	)	$	644,447
Net income	$	39,118	$	992	$	2,710	$	—		$	42,820