Segment Information (Tables)

9 Months Ended

Sep. 30, 2015

Segment Reporting [Abstract]

Results by Reportable Segment

(Thousands of Dollars)	Regulated Electric		Regulated Natural Gas			All Other			Reconciling Eliminations			Consolidated Total
Three Months Ended Sept. 30, 2015
Operating revenues (a)	$	224,666	$	11,088		$	407		$	—		$	236,161
Intersegment revenues	101		177						(278		)	—
Total revenues	$	224,767	$	11,265		$	407		$	(278	)	$	236,161
Net income (loss)	$	28,285	$	(1,993	)	$	(60	)	$	—		$	26,232

(Thousands of Dollars)	Regulated Electric		Regulated Natural Gas			All Other		Reconciling Eliminations			Consolidated Total
Three Months Ended Sept. 30, 2014
Operating revenues (a)	$	216,289	$	14,484		$	273	$	—		$	231,046
Intersegment revenues	93		425			—		(518		)	—
Total revenues	$	216,382	$	14,909		$	273	$	(518	)	$	231,046
Net income (loss)	$	21,227	$	(2,003	)	$	806	$	—		$	20,030

^(a)  Operating revenues include $42 million and $33 million of affiliate electric revenue for the three months ended Sept. 30, 2015 and 2014, respectively.

(Thousands of Dollars)	Regulated Electric			Regulated Natural Gas		All Other			Reconciling Eliminations			Consolidated Total
Nine Months Ended Sept. 30, 2015
Operating revenues (a)(b)	$	634,571		$	91,273	$	1,090		$	—		$	726,934
Intersegment revenues	308			475		—			(783		)	—
Total revenues	$	634,879		$	91,748	$	1,090		$	(783	)	$	726,934
Net income (loss)	$	57,586	(b)	$	3,714	$	(289	)	$	—		$	61,011

(Thousands of Dollars)	Regulated Electric		Regulated Natural Gas		All Other		Reconciling Eliminations			Consolidated Total
Nine Months Ended Sept. 30, 2014
Operating revenues (a)	$	625,663	$	117,814	$	825	$	—		$	744,302
Intersegment revenues	308		4,191		—		(4,499		)	—
Total revenues	$	625,971	$	122,005	$	825	$	(4,499	)	$	744,302
Net income	$	48,092	$	5,565	$	2,630	$	—		$	56,287

^(a)  Operating revenues include $121 million and $97 million of affiliate electric revenue for the nine months ended Sept. 30, 2015 and 2014, respectively.

^(b)  Includes a net of tax charge related to the Monticello LCM/EPU project.  See Note 5.