Segments and Related Information (Tables)

12 Months Ended

Dec. 31, 2011

Segments and Related Information [Abstract]

Schedule of Continuing Operation Revenues and Income of Reportable Segments

The accounting policies of the segments are the same as those described in Note 1.

	Regulated		Regulated		All			Reconciling			Consolidated
(Thousands of Dollars)	Electric		Natural Gas		Other			Eliminations			Total
2011
Operating revenues from external customers	$	8,766,593	$	1,811,926	$	76,251		$	-		$	10,654,770
Intersegment revenues		1,269		2,358		-			(3,627	)		-
Total revenues	$	8,767,862	$	1,814,284	$	76,251		$	(3,627	)	$	10,654,770
Depreciation and amortization	$	773,392	$	106,870	$	10,357		$	-		$	890,619
Interest charges and financing costs		402,668		52,115		108,134			-			562,917
Income tax expense (benefit)		473,848		57,408		(62,940	)		-			468,316
Income (loss) from continuing operations		788,967		101,842		(49,435	)		-			841,374

	Regulated		Regulated		All			Reconciling			Consolidated
(Thousands of Dollars)	Electric		Natural Gas		Other			Eliminations			Total
2010
Operating revenues from external customers	$	8,451,845	$	1,782,582	$	76,520		$	-		$	10,310,947
Intersegment revenues		1,015		5,653		-			(6,668	)		-
Total revenues	$	8,452,860	$	1,788,235	$	76,520		$	(6,668	)	$	10,310,947
Depreciation and amortization	$	748,815	$	99,220	$	10,847		$	-		$	858,882
Interest charges and financing costs		380,074		49,314		119,233			-			548,621
Income tax expense (benefit)		434,756		59,790		(57,911	)		-			436,635
Income (loss) from continuing operations		665,155		114,554		(27,753	)		-			751,956

	Regulated		Regulated		All			Reconciling			Consolidated
(Thousands of Dollars)	Electric		Natural Gas		Other			Eliminations			Total
2009
Operating revenues from external customers	$	7,704,723	$	1,865,703	$	73,877		$	-		$	9,644,303
Intersegment revenues		816		2,931		-			(3,747	)		-
Total revenues	$	7,705,539	$	1,868,634	$	73,877		$	(3,747	)	$	9,644,303
Depreciation and amortization	$	711,090	$	95,633	$	11,329		$	-		$	818,052
Interest charges and financing costs		371,525		44,572		105,758			-			521,855
Income tax expense (benefit)		357,128		81,956		(67,770	)		-			371,314
Income (loss) from continuing operations		611,851		108,948		(35,275	)		-			685,524