CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating revenue:
Electric	$ 633,553	$ 614,634
Gas	387,443	384,765
Other	4,379	419
Total operating revenue	1,025,375	999,818
Energy costs:
Purchased electricity	181,157	175,043
Electric generation fuel	75,436	59,087
Residential exchange	(30,003)	(22,551)
Purchased gas	191,306	189,983
Unrealized (gain) loss on derivative instruments, net	(7,839)	(75,692)
Utility operations and maintenance	144,076	129,235
Non-utility expense and other	3,422	(994)
Depreciation	91,184	88,178
Amortization	10,535	5,744
Conservation amortization	28,982	34,107
Taxes other than income taxes	100,818	99,943
Total operating expenses	789,074	682,083
Operating income	236,301	317,735
Other income (deductions):
Other income	4,242	12,012
Other expense	(1,582)	(1,542)
Non-hedged interest rate derivative expense	(747)	1,028
Interest charges:
AFUDC	1,153	4,648
Interest expense	(90,255)	(95,816)
Income (loss) before income taxes	149,112	238,065
Income tax (benefit) expense	41,520	70,590
Net income (loss)	107,592	167,475
Subsidiaries [Member]
Operating revenue:
Electric	633,553	614,634
Gas	387,443	384,765
Other	4,379	308
Total operating revenue	1,025,375	999,707
Energy costs:
Purchased electricity	181,157	175,043
Electric generation fuel	75,436	59,087
Residential exchange	(30,003)	(22,551)
Purchased gas	191,306	189,983
Unrealized (gain) loss on derivative instruments, net	(7,270)	(72,740)
Utility operations and maintenance	144,076	129,235
Non-utility expense and other	6,177	3,091
Depreciation	91,184	88,178
Amortization	10,535	5,744
Conservation amortization	28,982	34,107
Taxes other than income taxes	100,818	99,943
Total operating expenses	792,398	689,120
Operating income	232,977	310,587
Other income (deductions):
Other income	4,240	12,012
Other expense	(1,582)	(1,542)
Interest charges:
AFUDC	1,153	4,648
Interest expense	(64,137)	(65,977)
Interest expense on parent note	(26)	(29)
Income (loss) before income taxes	172,625	259,699
Income tax (benefit) expense	51,542	79,761
Net income (loss)	$ 121,083	$ 179,938