Unaudited Condensed Consolidated Statements Of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
UTILITY OPERATING REVENUES	$ 292,477	$ 314,160	$ 624,678	$ 669,463
Operation:
Fuel	77,084	97,844	162,516	201,942
Other operating expenses	54,832	55,393	109,808	117,512
Power purchased	31,409	26,384	73,985	64,132
Maintenance	40,755	32,778	72,037	64,751
Depreciation and amortization	42,931	46,380	89,376	92,435
Taxes other than income taxes	10,559	11,004	23,492	23,212
Income taxes - net	8,781	11,203	26,982	27,762
Total utility operating expenses	266,351	280,986	558,196	591,746
UTILITY OPERATING INCOME	26,126	33,174	66,482	77,717
OTHER INCOME AND (DEDUCTIONS):
Allowance for equity funds used during construction	3,079	1,350	6,297	2,963
Loss on early extinguishment of debt	(19,323)	0	(19,323)	0
Miscellaneous income and (deductions) - net	(742)	(566)	(1,368)	(1,541)
Income tax benefit applicable to nonoperating income	12,557	5,397	18,581	11,151
Total other income and (deductions) - net	(4,429)	6,181	4,187	12,573
INTEREST AND OTHER CHARGES:
Interest on long-term debt	27,695	26,659	55,341	53,099
Other interest	499	466	948	919
Allowance for borrowed funds used during construction	(2,567)	(749)	(5,233)	(1,732)
Amortization of redemption premiums and expense on debt	1,335	1,316	2,669	2,635
Total interest and other charges - net	26,962	27,692	53,725	54,921
NET (LOSS) INCOME	(5,265)	11,663	16,944	35,369
LESS: PREFERRED DIVIDENDS OF SUBSIDIARY	804	804	1,607	1,607
NET (LOSS) INCOME APPLICABLE TO COMMON STOCK	$ (6,069)	$ 10,859	$ 15,337	$ 33,762