RATE AND OTHER REGULATORY MATTERS (Details 2) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2013	Dec. 31, 2016
Regulatory Assets
Regulatory Assets, Noncurrent	$ 2,172.0		$ 2,130.0
SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	2,068.0		2,030.0
PSNC Energy [Member]
Regulatory Assets
Pipeline integrity management costs, amount deferred pending future approval of rate recovery	16.0
Pipeline integrity management costs, amount recovering beginning November 2016	$ 20.3
Deferred Income Tax Charges [Member]
Regulatory Assets
Regulatory Asset, Amortization Period	85 years
Regulatory Assets, Noncurrent	$ 321.0		316.0
Deferred Income Tax Charges [Member] | SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	$ 313.0		307.0
Asset Retirement Obligation Costs [Member]
Regulatory Assets
Regulatory Asset, Amortization Period	110 years
Regulatory Assets, Noncurrent	$ 423.0		425.0
Asset Retirement Obligation Costs [Member] | SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	400.0		403.0
Pension Costs [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	$ 331.0		342.0
Pension Costs [Member] | SCEG
Regulatory Assets
Regulatory Asset, Amortization Period	11 years
Regulatory Assets, Noncurrent	$ 299.0		309.0
Pension costs, electric [Member] | SCEG
Regulatory Assets
Regulatory Asset, Amortization Period		30 years
Deferred Losses On Interest Rate Derivatives [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	630.0		620.0
Deferred Losses On Interest Rate Derivatives [Member] | SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	630.0		620.0
unrecovered plant [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	111.0		117.0
unrecovered plant [Member] | SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	111.0		117.0
Demand Side Management programs [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	$ 59.0		59.0
Demand Side Management programs [Member] | SCEG
Regulatory Assets
Regulatory Asset, Amortization Period	5 years
Regulatory Assets, Noncurrent	$ 59.0		59.0
carrying cost on nuclear [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	$ 41.0		32.0
carrying cost on nuclear [Member] | SCEG
Regulatory Assets
Regulatory Asset, Amortization Period	10 years
Regulatory Assets, Noncurrent	$ 41.0		32.0
Pipeline integrity management costs [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	42.0		33.0
Pipeline integrity management costs [Member] | SCEG
Regulatory Assets
Pipeline integrity management costs, annual amortization amount	1.9
Regulatory Assets, Noncurrent	$ 7.0		6.0
Pipeline integrity management costs [Member] | PSNC Energy [Member]
Regulatory Assets
Regulatory Asset, Amortization Period	5 years
Environmental Restoration Costs [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	$ 31.0		32.0
Environmental Restoration Costs [Member] | SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	25.0		26.0
Storm Costs [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	20.0		20.0
Storm Costs [Member] | SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	20.0		20.0
Deferred costs uncertain tax position [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	23.0		15.0
Deferred costs uncertain tax position [Member] | SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	23.0		15.0
Other Regulatory Assets [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	140.0		119.0
Other Regulatory Assets [Member] | SCEG
Regulatory Assets
Regulatory Assets, Noncurrent	$ 140.0		$ 116.0