EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Millions | 12 Months Ended |
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year, Description | | no | | |
Defined Benefit Plan, Accumulated Benefit Obligation | | $ 905.8 | $ 874.3 | |
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate | | 5.00% | | |
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation | | $ 1.6 | 0.8 | |
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation | | $ 1.4 | $ 0.7 | |
Defined Benefit Plan Health Care Cost Trend Rate, Assumed | | 7.00% | | |
Defined Benefit Plan, Target Allocation, Equity Securities | | 58.00% | 57.00% | |
Defined Benefit Plan, Target Plan Asset Allocations | | 31.00% | 32.00% | |
Defined Benefit Plan, Target Plan Asset Allocation, Hedge Funds | | 11.00% | 11.00% | |
Other Postretirement Benefits | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Plan Assets, Benefits Paid | | | $ 11.1 | |
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant | | $ 1.3 | 1.7 | |
Defined Benefit Plan, Benefit Obligation | | 289.2 | 274.7 | $ 253.6 |
Defined Benefit Plan, Service Cost | | 4.5 | 4.4 | 5.3 |
Defined Benefit Plan, Interest Cost | | 11.5 | 12.1 | $ 11.4 |
Defined Benefit Plan, Actuarial Net (Gains) Losses | | $ (9.7) | $ (14) | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | | 3.74% | 4.30% | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase | | 3.00% | 3.00% | |
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate | | 5.00% | 5.00% | 5.00% |
Defined Benefit Plan, Fair Value of Plan Assets | | $ 0 | $ 0 | |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | | (289.2) | (274.7) | |
Liability, Defined Benefit Plan, Current | | (13.5) | (12.6) | |
Liability, Other Postretirement Defined Benefit Plan, Noncurrent | | (275.7) | (262.1) | |
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax | | 3.5 | 2.5 | |
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax | | 0 | 0 | |
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax | | 3.5 | 2.5 | |
pension and other postretirement benefit plans, regulated assets, net gains, before tax | | 43.3 | 34.7 | |
Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax | | 0 | 0 | |
Pension and other postretirement benefit plans, regulatory assets, before tax | | 43.3 | 34.7 | |
Defined Benefit Plan, Shared Costs Deferred | | 14.7 | 15.8 | |
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax | | 9.4 | 11.1 | $ (18) |
Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax | | (0.8) | (0.4) | (1.8) |
Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax | | 0 | (0.3) | (0.3) |
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax | | $ 8.6 | $ 10.4 | $ (20.1) |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | | 4.30% | 4.78% | 4.30% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | | 3.00% | 3.00% | 3.00% |
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year | | 6.60% | 7.00% | 7.00% |
Defined Benefit Plan, Benefit Obligation, Benefits Paid | | $ 12.5 | | |
Pension Plan, Defined Benefit | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Plan Assets, Benefits Paid | | 72.4 | | |
Defined Benefit Plan, Benefit Obligation | | 933.2 | $ 904.3 | $ 855.4 |
Defined Benefit Plan, Service Cost | | 21.7 | 20.7 | 24.1 |
Defined Benefit Plan, Interest Cost | | 37.4 | 39.4 | 38.2 |
Defined Benefit Plan, Actuarial Net (Gains) Losses | | $ (42.2) | $ (45) | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | | 3.71% | 4.22% | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase | | 3.00% | 3.00% | |
Defined Benefit Plan, Fair Value of Plan Assets | | $ 849.6 | $ 793.6 | 781.7 |
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) | | 128.4 | 68.1 | |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | | (83.6) | (110.7) | |
Liability, Defined Benefit Pension Plan, Noncurrent | | (83.6) | (110.7) | |
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax | | 8.8 | 10.4 | |
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax | | 0.1 | 0.1 | |
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax | | 8.9 | 10.5 | |
pension and other postretirement benefit plans, regulated assets, net gains, before tax | | 194.8 | 236.1 | |
Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax | | 1.2 | 2.5 | |
Pension and other postretirement benefit plans, regulatory assets, before tax | | 196 | 238.6 | |
Defined Benefit Plan, Shared Costs Deferred | | 21.4 | 23.4 | |
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax | | (27.1) | 29.4 | 9.2 |
Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax | | (14.1) | (12.7) | (11.9) |
Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax | | (1.4) | (3.4) | (3.7) |
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax | | $ (42.6) | $ 13.3 | $ (6.4) |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets | | 7.25% | 7.50% | 7.50% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | | 4.22% | 4.68% | 4.20% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | | 3.00% | 3.00% | 3.00% |
Defined Benefit Plan, Benefit Obligation, Benefits Paid | | $ 72.4 | $ 56.2 | |
SCE&G | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year, Description | | no | | |
Defined Benefit Plan, Period for which Annual Base Earnings are Considered Under Average Pay Formula | | 3 | | |
Defined Benefit Plan, Accumulated Benefit Obligation | | $ 769.7 | 742.9 | |
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate | | 5.00% | | |
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation | | $ 1.3 | 0.6 | |
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation | | $ 1.1 | $ 0.6 | |
Defined Benefit Plan Health Care Cost Trend Rate, Assumed | | 7.00% | | |
Defined Benefit Plan, Target Allocation, Equity Securities | | 58.00% | 57.00% | |
Defined Benefit Plan, Target Plan Asset Allocations | | 31.00% | 32.00% | |
Defined Benefit Plan, Target Plan Asset Allocation, Hedge Funds | | 11.00% | 11.00% | |
SCE&G | Other Postretirement Benefits | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Plan Assets, Benefits Paid | | $ 10.3 | $ 9.1 | |
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant | | 1.1 | 1.3 | |
Defined Benefit Plan, Benefit Obligation | | 216.6 | 207.2 | $ 191.7 |
Defined Benefit Plan, Service Cost | | 3.7 | 3.6 | 4.4 |
Defined Benefit Plan, Interest Cost | | 9.5 | 9.9 | $ 9.4 |
Defined Benefit Plan, Actuarial Net (Gains) Losses | | (6.8) | (11.5) | |
Defined Benefit Plan, Amounts Funded to Parent | | $ (1.4) | $ (1.7) | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | | 3.74% | 4.30% | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase | | 3.00% | 3.00% | |
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate | | 5.00% | 5.00% | 5.00% |
Defined Benefit Plan, Fair Value of Plan Assets | | $ 0 | $ 0 | |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | | (216.6) | (207.2) | |
Liability, Defined Benefit Plan, Current | | (10.8) | (10.4) | |
Liability, Other Postretirement Defined Benefit Plan, Noncurrent | | (205.8) | (196.8) | |
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax | | 1.5 | 1 | |
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax | | 0 | 0 | |
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax | | 1.5 | 1 | |
pension and other postretirement benefit plans, regulated assets, net gains, before tax | | 35.9 | 29.3 | |
Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax | | 0 | 0 | |
Pension and other postretirement benefit plans, regulatory assets, before tax | | 35.9 | 29.3 | |
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax | | 7.3 | 9.2 | $ (14) |
Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax | | (0.7) | (0.3) | 1.5 |
Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax | | 0 | (0.2) | (0.3) |
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax | | $ 6.6 | $ 8.7 | $ (15.8) |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | | 4.30% | 4.78% | 4.30% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | | 3.00% | 3.00% | 3.00% |
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year | | 6.60% | 7.00% | 7.00% |
SCE&G | Pension Plan, Defined Benefit | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Plan Assets, Benefits Paid | | $ 62 | $ 47.7 | |
Defined Benefit Plan, Benefit Obligation | | 793 | 768.4 | $ 724 |
Defined Benefit Plan, Service Cost | | 18.1 | 16.9 | 19.3 |
Defined Benefit Plan, Interest Cost | | 31.9 | 33.4 | 32.2 |
Defined Benefit Plan, Actuarial Net (Gains) Losses | | (36.6) | (41.8) | |
Defined Benefit Plan, Amounts Funded to Parent | | $ 0 | $ 0 | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | | 3.71% | 4.22% | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase | | 3.00% | 3.00% | |
Defined Benefit Plan, Fair Value of Plan Assets | | $ 781.3 | $ 732.9 | 720.1 |
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) | | 110.4 | 60.5 | |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | | (11.7) | (35.5) | |
Liability, Defined Benefit Pension Plan, Noncurrent | | (11.7) | (35.5) | |
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax | | 2.1 | 1.9 | |
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax | | 0 | 0 | |
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax | | 2.1 | 1.9 | |
pension and other postretirement benefit plans, regulated assets, net gains, before tax | | 171.4 | 208.8 | |
Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax | | 1 | 2.2 | |
Pension and other postretirement benefit plans, regulatory assets, before tax | | 172.4 | 211 | |
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax | | (24.8) | 26.3 | 12.2 |
Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax | | (12.5) | (11.2) | (10.4) |
Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax | | (1.3) | (3) | (3.1) |
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax | | $ (38.6) | $ 12.1 | $ (1.3) |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets | | 7.25% | 7.50% | 7.50% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | | 4.22% | 4.68% | 4.20% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | | 3.00% | 3.00% | 3.00% |
Pension Costs [Member] | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Deferred Debit Attributable to Share of Regulatory Authority | | $ 1 | | |
Pension Costs [Member] | SCE&G | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Deferred Debit Attributable to Share of Regulatory Authority | | $ 2 | | |
Regulatory assets, expected recovery period (in years) | | 11 years | | |
Scenario, Forecast [Member] | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets | 7.00% | | | |
Defined Benefit Plan, Target Allocation, Equity Securities | 58.00% | | | |
Defined Benefit Plan, Target Plan Asset Allocations | 33.00% | | | |
Defined Benefit Plan, Target Plan Asset Allocation, Hedge Funds | 9.00% | | | |
Scenario, Forecast [Member] | SCE&G | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets | 7.00% | | | |
Defined Benefit Plan, Target Allocation, Equity Securities | 58.00% | | | |
Defined Benefit Plan, Target Plan Asset Allocations | 33.00% | | | |
Defined Benefit Plan, Target Plan Asset Allocation, Hedge Funds | 9.00% | | | |