Segment Information (Tables)

9 Months Ended

Sep. 30, 2014

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, 2014
Operating revenues from external customers	$	2,616,351	$	236,649	$	16,807	$	—		$	2,869,807
Intersegment revenues	472		597		—		(1,069		)	—
Total revenues	$	2,616,823	$	237,246	$	16,807	$	(1,069	)	$	2,869,807
Net income	$	360,656	$	3,996	$	3,930	$	—		$	368,582

(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	$	2,599,925	$	205,358		$	17,055		$	—		$	2,822,338
Intersegment revenues	346		1,106			—			(1,452		)	—
Total revenues	$	2,600,271	$	206,464		$	17,055		$	(1,452	)	$	2,822,338
Net income (loss)	$	365,156	$	(174	)	$	(230	)	$	—		$	364,752

(Thousands of Dollars)	Regulated Electric		Regulated Natural Gas		All Other			Reconciling Eliminations			Consolidated Total
Nine Months Ended Sept. 30, 2014
Operating revenues from external customers	$	7,215,699	$	1,485,464	$	56,344		$	—		$	8,757,507
Intersegment revenues	1,262		4,967		—			(6,229		)	—
Total revenues	$	7,216,961	$	1,490,431	$	56,344		$	(6,229	)	$	8,757,507
Net income (loss)	$	731,766	$	96,629	$	(3,428	)	$	—		$	824,967

(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	$	6,911,998	$	1,216,275	$	55,827		$	—		$	8,184,100
Intersegment revenues	955		2,163		—			(3,118		)	—
Total revenues	$	6,912,953	$	1,218,438	$	55,827		$	(3,118	)	$	8,184,100
Net income (loss)	$	740,347	$	80,698	$	(22,866	)	$	—		$	798,179