RATE AND OTHER REGULATORY MATTERS (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012 MW	Sep. 30, 2012	Dec. 31, 2012 MW	Dec. 31, 2011	Jul. 31, 2011	Dec. 31, 2010	May 01, 2011
Regulatory Assets:
Regulatory assets		$ 1,464.0		$ 1,464.0	$ 1,279.0
Amount Recovered Through Electric Rates to Offset Turbine Expenses				18.4
Accrual period of nuclear refueling charges (in months)				18
Public Utilities, Percent Increase (Decrease) in Retail Natural Gas Rates				2.10%
Defined Benefit Pension Plan, Liabilities, Noncurrent		0		0
Regulatory Noncurrent Liability, Amortization Period				30
Deferred Income Tax Charges [Member]
Regulatory Assets:
Regulatory assets		254.0		254.0	243.0
Under-collections-electric fuel adjustment clause
Regulatory Assets:
Regulatory assets		66.0		66.0	28.0
Environmental remediation costs
Regulatory Assets:
Regulatory assets		44.0		44.0	30.0
Asset Retirement Obligation Costs [Member]
Regulatory Assets:
Regulatory assets		319.0		319.0	316.0
Franchise agreements
Regulatory Assets:
Regulatory assets		36.0		36.0	40.0
Deferred employee benefit plan costs
Regulatory Assets:
Regulatory assets		460.0		460.0	392.0
Planned major maintenance
Regulatory Assets:
Regulatory assets		6.0		6.0	6.0
Deferred losses on interest rate derivatives
Regulatory Assets:
Regulatory assets		151.0		151.0	154.0
Regulatory assets, expected recovery period (in years)				30
Utility Plant [Domain]
Regulatory Assets:
Regulatory assets, expected recovery period (in years)				14
Deferred pollution control costs
Regulatory Assets:
Regulatory assets		38.0		38.0	25.0
Other.
Regulatory Assets:
Regulatory assets		70.0		70.0	45.0
Regulatory assets, expected recovery period (in years)				30
SCE&G
Regulatory Assets:
Public Utilities, Increase (Decrease) in Retail Natural Gas Rates Requested and Approved under RSA				7.5	8.6		10.4
Public Utilities, Property, Plant and Equipment Identifiable Capital Costs				278
Capital Cost Related to New Federal Healthcare Etc.			1
Share in Approved Capital Costs		8.0		8.0				173.9
Public Utilities Additional Labor Expenses for Oversight of New Units				132
Regulatory assets		1,377.0		1,377.0	1,206.0
Regulatory assets, expected recovery period (in years)				30
Public Utilities Base Fuel under Collected Balance Recovery Period				12
MPG enviromental remediatio				28
Environmental Remediation Costs Recognized in Regulatory Assets		38.5		38.5
Amount Recovered Through Electric Rates to Offset Turbine Expenses	17.2	18.4
Accrual period of nuclear refueling charges (in months)				18
Public Utilities, Percent Increase (Decrease) in Retail Natural Gas Rates							2.10%
Public Utilities, Percent Increase (Decrease) in Retail Electric Rates		4.23%		2.30%	2.40%	4.88%	2.30%
power generation capacity six coal fired units		730		730
Amount Allowed to be Recovered through Electric Rates to Offset Incremental Storm Damage Costs				100
Annual Storm Damage Costs not offset by Amounts Recovered through Electric Rates				2.5
Defined Benefit Pension Plan, Liabilities, Noncurrent		63		63
Regulatory Noncurrent Liability, Amortization Period				30
SCE&G | Deferred Income Tax Charges [Member]
Regulatory Assets:
Regulatory assets		248.0		248.0	238.0
Regulatory assets, expected recovery period (in years)				70
SCE&G | Under-collections-electric fuel adjustment clause
Regulatory Assets:
Regulatory assets		66.0		66.0	28.0
SCE&G | Environmental remediation costs
Regulatory Assets:
Regulatory assets		39.0		39.0	25.0
SCE&G | Asset Retirement Obligation Costs [Member]
Regulatory Assets:
Regulatory assets		304.0		304.0	301.0
Regulatory assets, expected recovery period (in years)				95
SCE&G | Franchise agreements
Regulatory Assets:
Regulatory assets		36.0		36.0	40.0
Regulatory assets, expected recovery period (in years)				20
SCE&G | Deferred employee benefit plan costs
Regulatory Assets:
Regulatory assets		405.0		405.0	348.0
Regulatory assets, expected recovery period (in years)				12
SCE&G | Planned major maintenance
Regulatory Assets:
Regulatory assets		6.0		6.0	6.0
SCE&G | Deferred losses on interest rate derivatives
Regulatory Assets:
Regulatory assets		151.0		151.0	154.0
SCE&G | Deferred pollution control costs
Regulatory Assets:
Regulatory assets		38.0		38.0	25.0
SCE&G | Canadys Refined Coal LLC [Member]
Regulatory Assets:
Regulatory assets		20.0		20.0	0
SCE&G | Other.
Regulatory Assets:
Regulatory assets		$ 64.0		$ 64.0	$ 41.0