SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Accounting Policies [Abstract]
Equity investment impairments	$ 0		$ 0		$ 0
TEFA and PUA included in both utility revenue and cost of sales	5,200,000		6,000,000		8,000,000
Decrease in TEFA revenue based tax rate	25.00%		25.00%
Utility Plant:
Production Plant	296,000		296,000
Storage Plant	22,538,000		20,316,000
Transmission Plant	248,074,000		250,886,000
Distribution Plant	1,417,939,000		1,297,619,000
General Plant	53,162,000		49,586,000
Other Plant	1,855,000		1,855,000
Utility Plant in Service	1,743,864,000		1,620,558,000
Construction Work in Progress	72,940,000		38,232,000
Total Utility Plant	1,816,804,000		1,658,790,000
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
ARO as of January 1,	38,892,000		29,388,000
Accretion	1,514,000		1,870,000
Additions	743,000		989,000
Settlements	(1,630,000)		(1,603,000)
Revisions in Estimated Cash Flows	1,659,000	[1]	8,248,000	[1]
ARO as of December 31,	41,178,000		38,892,000		29,388,000
Composite annual rate for all depreciable utility property	2.30%		2.40%		2.30%
Interest capitalized	$ 8,200,000		$ 6,500,000		$ 1,100,000

[1] The revision in estimated cash flows in 2013 reflects an increase in the inflation rate used to determine the ARO settlement amount. In 2012, the revision in estimated cash flows reflected increases in the contractual cost as well as changes in the discount rates used to determine the ARO. A corresponding increase was made to regulatory assets, thus having no impact on earnings.