NATURE OF OPERATIONS AND FINANCIAL STATEMENT PRESENTATION Fortis Acquisition of UNS Energy (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Aug. 15, 2014	Oct. 10, 2014 Subsequent Event [Member]	Sep. 30, 2014 Total Bill Credit Refunds Over 5 Years [Member]	Sep. 30, 2014 Bill Credit Refunds in Year 1 [Member]	Sep. 30, 2014 Annual Bill Credit Refunds in Years 2 Through 5 [Member]	Aug. 15, 2014 Fortis Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price							$ 60.25
Fortis Acquisition Direct Customer Benefit				$ 19	$ 6	$ 3
years over which customer benefits are to be paid				5
Portion of Net Income Entity can Dividend to Parent	60.00%
Length in Periods of Restrictions On Payment Of Dividends (in Years)	5
Required Equity Capitalization for Regulated Utilities Prior to Dividend Payment	50.00%
Required Equity Investment By Acquiring Company Per Merger Settlement Agreement Subject to Regulatory Approval		220
Initial Equity Investment By Acquiring Company To Parent of Filer		37
Additional post merger equity contribution to parent of entity			200
Proceeds from Contributions from Parent			175
Merger-Related Costs Recorded through Closing of Merger	$ 15