RATE AND OTHER REGULATORY MATTERS (Details)	3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($) MW	Sep. 30, 2014 USD ($)	Mar. 31, 2014	Jun. 30, 2015	Sep. 30, 2015 USD ($) MW $ / shares	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Sep. 30, 2013 USD ($)
Rate Matters [Line Items]
Depreciation Study 2015, Effect Of Lower Depreciation Rates Annually, Dollars					$ 29,000,000
Depreciation Study 2015, Effect Of Lower Depreciation Rates Annually, Per Share | $ / shares					$ 0.12
Depreciation Study 2015, Effect Of Lower Depreciation Rates For YTD September 2015, Dollars					$ 22,000,000
Depreciation Study 2015, Effect Of Lower Depreciation Rates for YTD September 2015, Per Share | $ / shares					$ 0.09
Depreciation Study 2015, Undercollected Fuel Amount Offset by Lower Depreciation Rates, Dollars					$ 14,500,000.0
Depreciation Study 2015, Undercollected Fuel Amount Offset by Lower Depreciation Rates, Per Share | $ / shares					$ 0.06
Depreciation Study 2015, Increase in Net Income	$ 4,500,000				$ 4,500,000.0
Carrying cost recovery					(9,000,000)	$ (7,000,000)
Regulatory Assets, Noncurrent	1,884,000,000				$ 1,884,000,000		$ 1,823,000,000
Public Utilities Base Fuel under Collected Balance Recovery Period					12
Amortization Period For Carrying Cost On Accumlated Deferred Income Tax Assets Associated With New Units					10
SCEG
Rate Matters [Line Items]
Amounts Recovered Through Electric Rates to offset Nuclear Related Outage Costs					$ 17,200,000
Fuel Costs					10,300,000
Undercollected balance fuel	$ 46,000,000				$ 46,000,000
Capacity of renewable energy facilities by 2020 | MW	85				85
Capacity of renewable energy facilities by 2016 | MW	30				30
Depreciation Study 2015, Effect Of Lower Depreciation Rates Annually, Dollars					$ 29,000,000
Depreciation Study 2015, Effect Of Lower Depreciation Rates for YTD September 2015, Per Share | $ / shares					$ 22,000,000
Depreciation Study 2015, Undercollected Fuel Amount Offset by Lower Depreciation Rates, Dollars					$ 14,500,000.0
Depreciation Study 2015, Increase in Net Income	$ 4,500,000				4,500,000.0
Carrying costs on deferred income tax assets	2,400,000	$ 1,600,000			6,500,000	4,100,000
Carrying cost recovery					(9,000,000)	(7,000,000)
Regulatory Assets, Noncurrent	1,808,000,000				$ 1,808,000,000		1,745,000,000
Allowable return on common equity (as a percent)				11.00%	11.00%
Demand Side Management Program Costs, Noncurrent	32,000,000	$ 15,400,000			$ 32,000,000	$ 15,400,000			$ 16,900,000
Increase (decrease) in retail electric rate requested under the BLRA					$ 65,000,000		$ 66,000,000	$ 67,200,000
Public Utilities, Percent Increase (Decrease) in Retail Electric Rates					0.00%		0.00%	2.90%
Public Utilities, Percent Increase (Decrease) in Retail Natural Gas Rates							0.60%
Public Utilities changes in Retail Natural Gas Rates Approved under RSA							$ 2,600,000
Public Utilities, Rate Calculation Basis					12-month rolling average
Public Utilities Base Fuel under Collected Balance Recovery Period					12
Derivative, Gain on Derivative							17,800,000
Storm Damage Reserve Cost Applied							5,000,000
Demand side management recovery period					5
Amortization Period For Carrying Cost On Accumlated Deferred Income Tax Assets Associated With New Units					10
Pipeline Integrity Management Costs, Annual					$ 1,900,000.0
Amount Allowed to be Recovered through Electric Rates to Offset Incremental Storm Damage Costs					$ 100,000,000
PSNC Energy
Rate Matters [Line Items]
Public Utilities, Rate Calculation Basis			12
Pension costs, electric [Member] | SCEG
Rate Matters [Line Items]
Regulatory Noncurrent Asset Amortization Period					30 years
Defined Benefit Plan, Deferred Debit Attributable to Share of Regulatory Authority	63,000,000				$ 63,000,000
Pension costs, gas [Member] | SCEG
Rate Matters [Line Items]
Regulatory Noncurrent Asset Amortization Period								14 years
Defined Benefit Plan, Deferred Debit Attributable to Share of Regulatory Authority	14,000,000				14,000,000
Pension Costs [Member]
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	328,000,000				328,000,000		350,000,000
Pension Costs [Member] | SCEG
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	296,000,000				$ 296,000,000		310,000,000
Regulatory Noncurrent Asset Amortization Period					12 years			30 years
Other Regulatory Assets [Member]
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	43,000,000				$ 43,000,000		35,000,000
Regulatory Noncurrent Asset Amortization Period					30 years
Other Regulatory Assets [Member] | SCEG
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	45,000,000				$ 45,000,000		35,000,000
Deferred Pollution Control Costs
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	35,000,000				35,000,000		36,000,000
Deferred Pollution Control Costs | SCEG
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	35,000,000				35,000,000		36,000,000
Franchise agreement Costs
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	23,000,000				23,000,000		26,000,000
Franchise agreement Costs | SCEG
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	$ 23,000,000				23,000,000		$ 26,000,000
Planned major maintenance [Member] | SCEG
Rate Matters [Line Items]
Amounts Recovered through Electric Rates to offset Turbine Expense					18,400,000
Storm damage reserve [Member]
Rate Matters [Line Items]
Amount Allowed to be Recovered through Electric Rates to Offset Incremental Storm Damage Costs					$ 100,000,000