SEGMENTS OF BUSINESS (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Segment Reporting Information [Line Items]
Operating revenues	$ 160,477	$ 151,648	$ 492,399	$ 480,931
Operating income (loss)	12,439	15,418	85,486	74,047
Depreciation and amortization	11,819	11,088	23,420	21,850
Interest charges	6,234	5,664	12,215	10,630
Income taxes	3,004	265	25,514	22,236
Property additions	47,471	29,096	74,933	61,292
Indentifiable assets	2,061,579		2,061,579		2,076,615
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	169,049	160,488	514,966	498,894
Operating income (loss)	0	0	0	0
Depreciation and amortization	0	0	0	0
Interest charges	7,157	5,875	13,767	10,981
Income taxes	0	0	0	0
Property additions	0		0	0
Indentifiable assets	0		0
Operating Segments [Member] | Gas Utility Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	65,187	61,344	245,510	258,060
Operating income (loss)	7,065	9,224	65,558	57,015
Depreciation and amortization	10,375	9,740	20,678	19,225
Interest charges	4,895	4,163	9,924	8,178
Income taxes	1,065	2,125	23,111	20,264
Property additions	38,638	26,802	59,076	58,533
Indentifiable assets	1,492,205		1,492,205		1,468,635
Operating Segments [Member] | Wholesale Energy Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	6,475	(4,773)	54,746	49,668
Operating income (loss)	1,438	(9,645)	11,095	10,649
Depreciation and amortization	68	65	134	137
Interest charges	9	15	22	27
Income taxes	858	(3,828)	5,020	4,649
Property additions	6	0	30	6
Indentifiable assets	225,022		225,022		237,978
Operating Segments [Member] | Retail Energy Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	91,317	98,409	202,676	180,255
Operating income (loss)	3,960	15,358	9,100	5,633
Depreciation and amortization	1,198	1,075	2,269	2,150
Interest charges	1,564	1,437	2,637	2,459
Income taxes	1,011	2,050	(2,691)	(2,855)
Property additions	8,724	1,998	15,445	2,252
Indentifiable assets	261,801		261,801		224,507
Operating Segments [Member] | Retail Energy Operations [Member] | Retail Gas and Other Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	23,042	25,781	60,284	61,615
Operating income (loss)	(59)	(60)	714	646
Depreciation and amortization	10	9	17	18
Interest charges	51	35	111	57
Income taxes	24	120	538	490
Property additions	2	6	15	14
Indentifiable assets	25,426		25,426		21,532
Operating Segments [Member] | Retail Energy Operations [Member] | Retail Electric Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	54,258	58,868	114,153	90,818
Operating income (loss)	2,978	14,233	6,841	2,430
Depreciation and amortization	0	0	0	0
Interest charges	0	0	0	0
Income taxes	1,217	5,847	2,795	998
Property additions	0	0	0	0
Indentifiable assets	34,911		34,911		37,383
Operating Segments [Member] | Retail Energy Operations [Member] | On-site Energy Production [Member]
Segment Reporting Information [Line Items]
Operating revenues	9,863	9,180	19,651	18,530
Operating income (loss)	1,273	1,445	2,367	2,555
Depreciation and amortization	1,113	979	2,103	1,956
Interest charges	1,513	1,402	2,526	2,402
Income taxes	(864)	(3,815)	(7,657)	(4,355)
Property additions	8,590	1,929	15,297	2,164
Indentifiable assets	181,084		181,084		147,064
Operating Segments [Member] | Retail Energy Operations [Member] | Appliance Service Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,154	4,580	8,588	9,292
Operating income (loss)	(232)	(260)	(822)	2
Depreciation and amortization	75	87	149	176
Interest charges	0	0	0	0
Income taxes	634	(102)	1,633	12
Property additions	132	63	133	74
Indentifiable assets	20,380		20,380		18,528
Operating Segments [Member] | Corporate and Services [Member]
Segment Reporting Information [Line Items]
Operating revenues	6,070	5,508	12,034	10,911
Operating income (loss)	(24)	481	(267)	750
Depreciation and amortization	178	208	339	338
Interest charges	689	260	1,184	317
Income taxes	70	(82)	74	178
Property additions	103	296	382	501
Indentifiable assets	100,763		100,763		168,788
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating revenues	(8,572)	(8,840)	(22,567)	(17,963)
Operating income (loss)	0	0	0	0
Depreciation and amortization	0	0	0	0
Interest charges	(923)	(211)	(1,552)	(351)
Income taxes	0	0	0	0
Property additions	0		0	0
Indentifiable assets	(18,678)		(18,678)		(24,183)
Segment, Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Indentifiable assets	$ 466		$ 466		$ 890