SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Accounting Policies [Abstract]
Amount of Transitional Energy Facility Assessment and Public Utilities Assessment included in revenues and cost of sales	$ 0.9	$ 1.2	$ 3.4	$ 5.0
Decrease in TEFA revenue based tax rate					25.00%

The amount of revenue-based energy taxes collected from customers related to Transitional energy Facility Assessment (TEFA) and Public Utilities Assessment (PUA), which are included in both utility revenue and in cost of sales on the consolidated statement of income.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration