Segment Information (Tables)

9 Months Ended

Sep. 30, 2014

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

Financial data for the business segments are as follows (in thousands):

Three Months Ended
September 30, 2014	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	212,430		$	39,482		$	—		$	—	$	251,912
Cost of sales	84,720			9,872			—			—		94,592
Gross margin	127,710			29,610			—			—		157,320
Operating, general and administrative	48,528			21,005			(1,425		)	—		68,108
Property and other taxes	20,413			7,357			3			—		27,773
Depreciation and depletion	23,174			7,270			8			—		30,452
Operating income (loss)	35,595			(6,022		)	1,414			—		30,987
Interest expense	(14,025		)	(2,627		)	(2,142		)	—		(18,794		)
Other income (expense)	1,337			336			(2,112		)	—		(439		)
Income tax benefit	5,235			926			12,276			—		18,437
Net income (loss)	$	28,142		$	(7,387	)	$	9,436		$	—	$	30,191
Total assets	$	2,694,883		$	1,170,843		$	8,572		$	—	$	3,874,298
Capital expenditures	$	62,054		$	12,011		$	—		$	—	$	74,065

Three Months Ended
September 30, 2013	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	227,103		$	34,772		$	373		$	—	$	262,248
Cost of sales	95,264			9,034			—			—		104,298
Gross margin	131,839			25,738			373			—		157,950
Operating, general and administrative	49,155			18,521			4,864			—		72,540
Property and other taxes	19,381			6,572			3			—		25,956
Depreciation and depletion	22,150			5,895			8			—		28,053
Operating income (loss)	41,153			(5,250		)	(4,502		)	—		31,401
Interest expense	(14,302		)	(2,560		)	(194		)	—		(17,056		)
Other income	2,213			878			26			—		3,117
Income tax (expense) benefit	(8,412		)	3,520			3,077			—		(1,815		)
Net income (loss)	$	20,652		$	(3,412	)	$	(1,593	)	$	—	$	15,647
Total assets	$	2,542,068		$	1,082,294		$	9,288		$	—	$	3,633,650
Capital expenditures	$	55,579		$	9,823		$	—		$	—	$	65,402

Nine Months Ended
September 30, 2014	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	652,951		$	238,965		$	—		$	—	$	891,916
Cost of sales	273,754			100,740			—			—		374,494
Gross margin	379,197			138,225			—			—		517,422
Operating, general and administrative	144,933			66,254			3,370			—		214,557
Property and other taxes	61,322			22,961			9			—		84,292
Depreciation and depletion	69,398			21,716			25			—		91,139
Operating income (loss)	103,544			27,294			(3,404		)	—		127,434
Interest expense	(43,663		)	(7,979		)	(6,245		)	—		(57,887		)
Other income	3,204			876			650			—		4,730
Income tax (expense) benefit	(575		)	(3,334		)	13,149			—		9,240
Net income	$	62,510		$	16,857		$	4,150		$	—	$	83,517
Total assets	$	2,694,883		$	1,170,843		$	8,572		$	—	$	3,874,298
Capital expenditures	$	161,718		$	24,367		$	—		$	—	$	186,085

Nine Months Ended
September 30, 2013	Electric			Gas			Other			Eliminations		Total
Operating revenues	$	637,667		$	196,652		$	1,110		$	—	$	835,429
Cost of sales	260,879			82,528			—			—		343,407
Gross margin	376,788			114,124			1,110			—		492,022
Operating, general and administrative	142,594			56,899			9,248			—		208,741
Property and other taxes	57,549			19,968			8			—		77,525
Depreciation and depletion	67,454			17,206			25			—		84,685
Operating income (loss)	109,191			20,051			(8,171		)	—		121,071
Interest expense	(42,840		)	(7,553		)	(583		)	—		(50,976		)
Other income	4,926			1,753			81			—		6,760
Income tax (expense) benefit	(12,792		)	(153		)	3,980			—		(8,965		)
Net income (loss)	$	58,485		$	14,098		$	(4,693	)	$	—	$	67,890
Total assets	$	2,542,068		$	1,082,294		$	9,288		$	—	$	3,633,650
Capital expenditures	$	130,585		$	23,366		$	—		$	—	$	153,951