RATE AND OTHER REGULATORY MATTERS (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) MW	Mar. 31, 2015 USD ($)	Dec. 31, 2013	Dec. 31, 2015 USD ($)
Rate Matters [Line Items]
Reclassifications, Cash Flow Statement, Regulatory Assets, Use Of Cash	$ 96,000,000
Carrying cost recovery	(4,000,000)	$ (3,000,000)
Regulatory Assets, Noncurrent	$ 2,068,000,000			$ 1,937,000,000
MPG environmental remediation	24
PSNC Energy Rate Case Application, Increase Amount	$ 41,600,000
PSNC Energy Rate Case Application, Percentage Increase	0.00%
SCEG
Rate Matters [Line Items]
Reclassifications, Cash Flow Statement, Regulatory Assets, Use Of Cash	$ 96,000,000
Capacity of renewable energy facilities by 2020 | MW	80
Capacity of renewable energy facilities by 2016 | MW	30
SCPSC Order Reduction Of Total Fuel Cost Component Of Retail Electric Rates To Reflect Lower Projected Fuel Costs And Eliminate Over-Collection Balances	$ 61,000,000
SCPSC Order, Recovery Of Projected DER Program Costs	6,900,000
Carrying costs on deferred income tax assets	3,100,000	1,900,000
Carrying cost recovery	(4,000,000)	$ (3,000,000)
Regulatory Assets, Noncurrent	$ 1,986,000,000			1,857,000,000
Demand side management recovery period	5
SCPSC Order, Annual DSM Program Rate Rider Recovery Amount	$ 37,600,000
Environmental Restoration Costs [Member]
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	41,000,000			42,000,000
Environmental Restoration Costs [Member] | SCEG
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	$ 34,000,000			35,000,000
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
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
Pension Costs [Member]
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	323,000,000			325,000,000
Pension Costs [Member] | SCEG
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	$ 293,000,000			295,000,000
Regulatory Noncurrent Asset Amortization Period	12 years
Other Regulatory Assets [Member]
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	$ 153,000,000			144,000,000
Regulatory Noncurrent Asset Amortization Period	30 years
Other Regulatory Assets [Member] | SCEG
Rate Matters [Line Items]
Regulatory Assets, Noncurrent	$ 136,000,000			$ 129,000,000