EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Millions |
12 Months Ended |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
| Defined Benefit Plan Disclosure [Line Items] |
|
|
|
|
| Defined Benefit Plan, Plan Assets, Benefits Paid |
|
$ 71.7
|
|
|
| Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year, Description |
|
no
|
|
|
| Defined Benefit Plan, Accumulated Benefit Obligation |
|
$ 842.4
|
$ 905.8
|
|
| 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 |
|
$ 0.7
|
1.6
|
|
| Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation |
|
0.6
|
1.4
|
|
| Defined Benefit Plan, Plan Assets, Amount |
|
727.3
|
849.6
|
$ 793.6
|
| Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) |
|
(50.6)
|
128.4
|
|
| Defined Benefit Plan, Shared Costs Deferred |
|
$ 24.9
|
$ 21.4
|
|
| Defined Benefit Plan Health Care Cost Trend Rate, Assumed |
|
6.60%
|
|
|
| Defined Benefit Plan, Target Allocation, Equity Securities |
|
55.00%
|
58.00%
|
|
| Defined Benefit Plan, Target Plan Asset Allocations |
|
34.00%
|
31.00%
|
|
| Defined Benefit Plan, Target Plan Asset Allocation, Hedge Funds |
|
11.00%
|
11.00%
|
|
| Defined Benefit Plan, Benefit Obligation, Benefits Paid |
|
|
$ 72.4
|
|
| Other Postretirement Benefits |
|
|
|
|
| Defined Benefit Plan Disclosure [Line Items] |
|
|
|
|
| Defined Benefit Plan, Plan Assets, Benefits Paid |
|
|
12.5
|
|
| Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant |
|
$ 1.4
|
1.3
|
|
| Defined Benefit Plan, Benefit Obligation |
|
253.7
|
289.2
|
274.7
|
| Defined Benefit Plan, Service Cost |
|
4.6
|
4.5
|
4.4
|
| Defined Benefit Plan, Interest Cost |
|
10.1
|
11.5
|
$ 12.1
|
| Defined Benefit Plan, Actuarial Net (Gains) Losses |
|
$ 38.4
|
$ (9.7)
|
|
| Defined Benefit Plan, Ultimate Health Care Cost Trend Rate |
|
5.00%
|
5.00%
|
5.00%
|
| Defined Benefit Plan, Plan Assets, Amount |
|
$ 0.0
|
$ 0.0
|
|
| Defined Benefit Plan, Funded (Unfunded) Status of Plan |
|
(253.7)
|
(289.2)
|
|
| Liability, Defined Benefit Plan, Current |
|
(13.3)
|
(13.5)
|
|
| Liability, Other Postretirement Defined Benefit Plan, Noncurrent |
|
(240.4)
|
(275.7)
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax |
|
1.1
|
3.5
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax |
|
0.0
|
0.0
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax |
|
1.1
|
3.5
|
|
| pension and other postretirement benefit plans, regulated assets, net gains, before tax |
|
10.9
|
43.3
|
|
| Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax |
|
0.0
|
0.0
|
|
| Pension and other postretirement benefit plans, regulatory assets, before tax |
|
10.9
|
43.3
|
|
| Defined Benefit Plan, Shared Costs Deferred |
|
12.4
|
14.7
|
|
| Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax |
|
(31.8)
|
9.4
|
$ 11.1
|
| Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax |
|
(0.6)
|
(0.8)
|
(0.4)
|
| Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax |
|
0.0
|
0.0
|
(0.3)
|
| Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax |
|
$ (32.4)
|
$ 8.6
|
$ 10.4
|
| Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate |
|
3.74%
|
4.30%
|
4.78%
|
| 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 |
|
7.00%
|
6.60%
|
7.00%
|
| Defined Benefit Plan, Benefit Obligation, Benefits Paid |
|
$ 13.2
|
|
|
| Pension Plan, Defined Benefit |
|
|
|
|
| Defined Benefit Plan Disclosure [Line Items] |
|
|
|
|
| Defined Benefit Plan, Benefit Obligation |
|
863.5
|
$ 933.2
|
$ 904.3
|
| Defined Benefit Plan, Service Cost |
|
21.0
|
21.7
|
20.7
|
| Defined Benefit Plan, Interest Cost |
|
34.1
|
37.4
|
39.4
|
| Defined Benefit Plan, Actuarial Net (Gains) Losses |
|
$ 53.1
|
$ (42.2)
|
|
| Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate |
|
4.35%
|
3.71%
|
|
| Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase |
|
3.00%
|
3.00%
|
|
| Defined Benefit Plan, Plan Assets, Amount |
|
$ 727.3
|
$ 849.6
|
|
| Defined Benefit Plan, Funded (Unfunded) Status of Plan |
|
(136.2)
|
(83.6)
|
|
| Liability, Defined Benefit Plan, Current |
|
|
0.0
|
|
| Liability, Defined Benefit Pension Plan, Noncurrent |
|
(136.2)
|
(83.6)
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax |
|
12.8
|
8.8
|
|
| 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 |
|
12.9
|
8.9
|
|
| pension and other postretirement benefit plans, regulated assets, net gains, before tax |
|
230.4
|
194.8
|
|
| Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax |
|
0.7
|
1.2
|
|
| Pension and other postretirement benefit plans, regulatory assets, before tax |
|
231.1
|
196.0
|
|
| Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax |
|
46.7
|
(27.1)
|
29.4
|
| Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax |
|
(11.1)
|
(14.1)
|
(12.7)
|
| Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax |
|
(0.5)
|
(1.4)
|
(3.4)
|
| Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax |
|
$ 35.1
|
$ (42.6)
|
$ 13.3
|
| Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets |
|
7.00%
|
7.25%
|
7.50%
|
| Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate |
|
3.71%
|
4.22%
|
4.68%
|
| 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 |
|
$ 71.7
|
$ 72.4
|
|
| SCE&G |
|
|
|
|
| Defined Benefit Plan Disclosure [Line Items] |
|
|
|
|
| Defined Benefit Plan, Plan Assets, Benefits Paid |
|
$ 61.3
|
62.0
|
|
| 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 |
|
$ 714.3
|
769.7
|
|
| 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 |
|
$ 0.6
|
1.3
|
|
| Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation |
|
0.5
|
1.1
|
|
| Defined Benefit Plan, Plan Assets, Amount |
|
676.7
|
781.3
|
$ 732.9
|
| Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) |
|
$ (43.3)
|
$ 110.4
|
|
| Defined Benefit Plan Health Care Cost Trend Rate, Assumed |
|
6.60%
|
|
|
| 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 |
|
55.00%
|
58.00%
|
|
| Defined Benefit Plan, Target Plan Asset Allocations |
|
34.00%
|
31.00%
|
|
| 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 |
|
$ 10.4
|
$ 10.3
|
|
| Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant |
|
1.1
|
1.1
|
|
| Defined Benefit Plan, Benefit Obligation |
|
187.4
|
216.6
|
207.2
|
| Defined Benefit Plan, Service Cost |
|
3.6
|
3.7
|
3.6
|
| Defined Benefit Plan, Interest Cost |
|
8.0
|
9.5
|
$ 9.9
|
| Defined Benefit Plan, Actuarial Net (Gains) Losses |
|
30.7
|
(6.8)
|
|
| Defined Benefit Plan, Amounts Funded to Parent |
|
$ (0.8)
|
$ (1.4)
|
|
| Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate |
|
4.38%
|
3.74%
|
|
| 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, Plan Assets, Amount |
|
$ 0.0
|
$ 0.0
|
|
| Defined Benefit Plan, Funded (Unfunded) Status of Plan |
|
(187.4)
|
(216.6)
|
|
| Liability, Defined Benefit Plan, Current |
|
(10.5)
|
(10.8)
|
|
| Liability, Other Postretirement Defined Benefit Plan, Noncurrent |
|
(176.9)
|
(205.8)
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax |
|
0.5
|
1.5
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax |
|
0.0
|
0.0
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax |
|
0.5
|
1.5
|
|
| pension and other postretirement benefit plans, regulated assets, net gains, before tax |
|
9.0
|
35.9
|
|
| Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax |
|
0.0
|
0.0
|
|
| Pension and other postretirement benefit plans, regulatory assets, before tax |
|
9.0
|
35.9
|
|
| Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax |
|
(26.4)
|
7.3
|
$ 9.2
|
| Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax |
|
(0.5)
|
(0.7)
|
0.3
|
| Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax |
|
0.0
|
0.0
|
(0.2)
|
| Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax |
|
$ (26.9)
|
$ 6.6
|
$ 8.7
|
| Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate |
|
3.74%
|
4.30%
|
4.78%
|
| 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 |
|
7.00%
|
6.60%
|
7.00%
|
| SCE&G | Pension Plan, Defined Benefit |
|
|
|
|
| Defined Benefit Plan Disclosure [Line Items] |
|
|
|
|
| Defined Benefit Plan, Plan Assets, Benefits Paid |
|
$ 61.3
|
$ 62.0
|
|
| Defined Benefit Plan, Benefit Obligation |
|
732.3
|
793.0
|
$ 768.4
|
| Defined Benefit Plan, Service Cost |
|
17.1
|
18.1
|
16.9
|
| Defined Benefit Plan, Interest Cost |
|
29.0
|
31.9
|
33.4
|
| Defined Benefit Plan, Actuarial Net (Gains) Losses |
|
45.5
|
(36.6)
|
|
| Defined Benefit Plan, Amounts Funded to Parent |
|
$ 0.0
|
$ 0.0
|
|
| Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate |
|
4.35%
|
3.71%
|
|
| Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase |
|
3.00%
|
3.00%
|
|
| Defined Benefit Plan, Plan Assets, Amount |
|
$ 676.7
|
$ 781.3
|
|
| Defined Benefit Plan, Funded (Unfunded) Status of Plan |
|
(55.6)
|
(11.7)
|
|
| Liability, Defined Benefit Plan, Current |
|
|
0.0
|
|
| Liability, Defined Benefit Pension Plan, Noncurrent |
|
(55.6)
|
(11.7)
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax |
|
3.4
|
2.1
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax |
|
0.0
|
0.0
|
|
| Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax |
|
3.4
|
2.1
|
|
| pension and other postretirement benefit plans, regulated assets, net gains, before tax |
|
202.4
|
171.4
|
|
| Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax |
|
0.6
|
1.0
|
|
| Pension and other postretirement benefit plans, regulatory assets, before tax |
|
203.0
|
172.4
|
|
| Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax |
|
40.7
|
(24.8)
|
26.3
|
| Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax |
|
(9.7)
|
(12.5)
|
(11.2)
|
| Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax |
|
(0.4)
|
(1.3)
|
(3.0)
|
| Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax |
|
$ 30.6
|
$ (38.6)
|
$ 12.1
|
| Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets |
|
7.00%
|
7.25%
|
7.50%
|
| Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate |
|
3.71%
|
4.22%
|
4.68%
|
| 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 |
|
$ 1.0
|
|
|
| Pension Costs [Member] | SCE&G |
|
|
|
|
| Defined Benefit Plan Disclosure [Line Items] |
|
|
|
|
| Defined Benefit Plan, Deferred Debit Attributable to Share of Regulatory Authority |
|
$ 2.0
|
|
|
| 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, 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%
|
|
|
|