REGULATORY MATTERS (Details) (USD $)	0 Months Ended	9 Months Ended	12 Months Ended				0 Months Ended	9 Months Ended	12 Months Ended		0 Months Ended	12 Months Ended	0 Months Ended	9 Months Ended	12 Months Ended	0 Months Ended
	Dec. 01, 2010	Sep. 30, 2014	Dec. 31, 2010 APSC Approved Expension of ESR, November 1, 2010	Dec. 31, 2010 Self Insurance Costs APSC Approved Expension of ESR, November 1, 2010	Dec. 31, 2010 Force Majeure Event Costs APSC Approved Expension of ESR, November 1, 2010	Dec. 31, 2010 Force Majeure Events Costs APSC Approved Expension of ESR, November 1, 2010	Jan. 01, 2014 Alabama Public Service Commission	Sep. 30, 2014 Alabama Public Service Commission	Dec. 31, 2013 Alabama Public Service Commission	Dec. 31, 2012 Alabama Public Service Commission	Jan. 01, 2014 Alabama Public Service Commission Minimum	Dec. 31, 2013 Alabama Public Service Commission Minimum	Jan. 01, 2014 Alabama Public Service Commission Maximum	Sep. 30, 2014 Alabama Public Service Commission Maximum	Dec. 31, 2013 Alabama Public Service Commission Maximum	Jan. 01, 2014 Alabama Public Service Commission, Performance Based Adjustment	Dec. 01, 2014 Scenario, Forecast Alabama Public Service Commission
Public Utilities, General Disclosures [Line Items]
Public utilities, approved return on equity, percentage							10.80%				10.50%	13.15%	10.95%		13.65%	500.00%
Public utilities, approved equity capital structure, percentage														56.50%
Public utilities, maximum return on equity, percentage of prior year revenues								4.00%
Public utilities, reduction to revenues for rate making purposes								$ 22,500,000	$ 10,600,000	$ 6,300,000
Public utilities, approved rate increase (decrease), amount								(8,500,000)	10,300,000	7,800,000							2,400,000
Public utilities, rate increase (decrease), index range, margin								1.75%
Extraordinary Operating and maintenance expenses, minimum amount, charged to enhanced stability reserve				1,000,000.0	300,000	400,000
Negative revenue variance, large commercial and industrial customer budget, minimum amount, charged to enhanced stability reserve			400,000
Public utilities, recovery period	9 years	5 years
Amortization expense, enhanced stability reserve, annual amount		$ 700,000