EMPLOYEE BENEFIT PLANS (Details) - USD ($) | 4 Months Ended | 8 Months Ended | 12 Months Ended |
Dec. 31, 2013 | Aug. 31, 2013 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Defined Benefit Plan, Accumulated Benefit Obligation | | | | $ 829,300,000 | $ 888,300,000 | |
Defined Benefit Plan Health Care Cost Trend Rate, Assumed | | | | 7.00% | | |
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 | | | | $ 800,000 | 1,300,000 | |
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation | | | | 700,000 | 1,000,000 | |
Defined Benefit Plan, Fair Value of Plan Assets | | | | $ 782,000,000 | $ 862,000,000 | |
Transfers of fair value amounts into or out of Levels 1, 2 or 3 | | | | no | no | |
Defined Contribution Plan, Cost Recognized | | | | $ 26,200,000 | $ 25,800,000 | $ 23,400,000 |
Other Postretirement Benefits | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Adoption of new mortality tables in 2014, gain | | | | | 3,000,000 | |
Adoption of modified mortality tables in 2015, gain | | | | 2,400,000 | | |
Defined Benefit Plan, Benefit Obligation | $ 238,000,000 | | | 253,600,000 | 268,200,000 | 238,000,000 |
Service cost | | | | 5,300,000 | 4,600,000 | 5,900,000 |
Interest cost | | | | 11,400,000 | 12,000,000 | $ 11,100,000 |
Defined Benefit Plan, Contributions by Plan Participants | | | | 2,400,000 | 2,200,000 | |
Defined Benefit Plan, Actuarial Net (Gains) Losses | | | | 21,200,000 | (23,500,000) | |
Defined Benefit Plan, Benefits Paid | | | | $ (12,500,000) | $ (12,100,000) | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | | | | 4.78% | 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 Status of Plan | | | | (253,600,000) | (268,200,000) | |
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities | | | | (11,900,000) | (11,200,000) | |
Other Postretirement Defined Benefit Plan, Liabilities, Noncurrent | | | | (241,700,000) | (257,000,000) | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax | | | | 1,700,000 | 3,000,000 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax | | | | 0 | 100,000 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax | | | | 1,700,000 | 3,100,000 | |
pension and other postretirement benefit plans, regulated assets, net gains, before tax | | | | 24,000,000 | 43,800,000 | |
Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax | | | | 300,000 | 600,000 | |
Pension and other postretirement benefit plans, regulatory assets, before tax | | | | 24,300,000 | 44,400,000 | |
Defined Benefit Plan, Shared Costs Deferred | | | | 13.8 | 15.1 | |
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax | | | | $ (18,000,000) | $ 19,400,000 | $ (29,900,000) |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | | | | 4.30% | 5.19% | 4.19% |
Defined Benefit Plan, Amortization of Transition Obligations (Assets) | | | | $ 0 | $ 0 | $ 300,000 |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | | | | 3.00% | 3.75% | 3.75% |
Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax | | | | $ (1,800,000) | $ 0 | $ (2,700,000) |
Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax | | | | (300,000) | (300,000) | (600,000) |
Regulatory assets, prior service cost (credit), pension and other postretirement benefit plans, net of tax | | | | 0 | 0 | 0 |
Regulatory assets, amortization of transition obligation, pension and other postretirement benefit plans, net of tax | | | | 0 | 0 | (200,000) |
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax | | | | (20,100,000) | (19,100,000) | (33,400,000) |
Pension Plan, Defined Benefit | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Adoption of new mortality tables in 2014, gain | | | | | 26,000,000 | |
Adoption of modified mortality tables in 2015, gain | | | | 21,500,000 | | |
Defined Benefit Plan, Benefit Obligation | 823,000,000 | | | 855,400,000 | 919,500,000 | 823,000,000 |
Service cost | | | | 24,100,000 | 20,000,000 | 21,800,000 |
Interest cost | | | | 38,200,000 | 40,400,000 | 38,500,000 |
Defined Benefit Plan, Contributions by Plan Participants | | | | 0 | 0 | |
Defined Benefit Plan, Actuarial Net (Gains) Losses | | | | 62,400,000 | (100,100,000) | |
Defined Benefit Plan, Benefits Paid | | | | (64,000,000) | (64,000,000) | |
Defined Benefit Plan, Curtailments | | | | $ 0 | $ 0 | 9,900,000 |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | | | | 4.68% | 4.20% | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase | | | | 3.00% | 3.00% | |
Defined Benefit Plan, Fair Value of Plan Assets | $ 870,000,000 | | | $ 781,700,000 | $ 861,800,000 | 870,000,000 |
Defined Benefit Plan, Funded Status of Plan | | | | (73,700,000) | (57,700,000) | |
Defined Benefit Pension Plan, Liabilities, Noncurrent | | | | (73,700,000) | (57,700,000) | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax | | | | 10,400,000 | 8,100,000 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax | | | | 200,000 | 300,000 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax | | | | 10,600,000 | 8,400,000 | |
pension and other postretirement benefit plans, regulated assets, net gains, before tax | | | | 219,400,000 | 222,100,000 | |
Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax | | | | 5,900,000 | 9,600,000 | |
Pension and other postretirement benefit plans, regulatory assets, before tax | | | | 225,300,000 | 231,700,000 | |
Defined Benefit Plan, Shared Costs Deferred | | | | 20.3 | 17.8 | |
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax | | | | $ 9,200,000 | $ 101,300,000 | (157,500,000) |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | 5.07% | 4.10% | | 4.20% | 5.03% | |
Expected return on assets | | | | $ (62,000,000) | $ (66,700,000) | (61,400,000) |
Defined Benefit Plan, Amortization of Transition Obligations (Assets) | | | | 0 | 0 | 0 |
Defined Benefit Plan, Actual Return on Plan Assets | | | | $ (16,100,000) | $ 55,800,000 | |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | 3.00% | 3.75% | | 3.00% | 3.00% | |
Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax | | | | $ (11,900,000) | $ (4,000,000) | (14,700,000) |
Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax | | | | (3,700,000) | (3,200,000) | (5,200,000) |
Regulatory assets, prior service cost (credit), pension and other postretirement benefit plans, net of tax | | | | 0 | 0 | (8,900,000) |
Regulatory assets, amortization of transition obligation, pension and other postretirement benefit plans, net of tax | | | | 0 | 0 | 0 |
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax | | | | $ (6,400,000) | (94,100,000) | (186,300,000) |
SCE&G | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Defined Benefit Plan, Period for which Annual Base Earnings are Considered Under Average Pay Formula | | | | 3 | | |
Defined Benefit Plan, Accumulated Benefit Obligation | | | | $ 0 | 0 | |
Defined Benefit Plan Health Care Cost Trend Rate, Assumed | | | | 7.00% | | |
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 | 0 | |
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation | | | | 0 | 0 | |
Defined Benefit Plan, Fair Value of Plan Assets | | | | $ 720,000,000 | $ 784,000,000 | |
Transfers of fair value amounts into or out of Levels 1, 2 or 3 | | | | no | no | |
Defined Contribution Plan, Cost Recognized | | | | $ 21,800,000 | $ 20,700,000 | 18,700,000 |
SCE&G | Other Postretirement Benefits | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Adoption of new mortality tables in 2014, gain | | | | | 2,000,000 | |
Adoption of modified mortality tables in 2015, gain | | | | 2,000,000 | | |
Defined Benefit Plan, Benefit Obligation | $ 181,700,000 | | | 191,700,000 | 204,100,000 | 181,700,000 |
Service cost | | | | 4,400,000 | 3,600,000 | 4,600,000 |
Interest cost | | | | 9,400,000 | 9,400,000 | $ 8,700,000 |
Defined Benefit Plan, Contributions by Plan Participants | | | | 1,900,000 | 1,800,000 | |
Defined Benefit Plan, Actuarial Net (Gains) Losses | | | | 15,700,000 | (18,600,000) | |
Defined Benefit Plan, Benefits Paid | | | | $ (10,300,000) | $ (9,600,000) | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | | | | 4.78% | 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 Status of Plan | | | | (191,700,000) | (204,100,000) | |
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities | | | | (9,800,000) | (8,500,000) | |
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent | | | | 0 | 0 | |
Other Postretirement Defined Benefit Plan, Liabilities, Noncurrent | | | | (181,900,000) | (195,600,000) | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax | | | | 700,000 | 1,000,000 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax | | | | 0 | 0 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax | | | | 700,000 | 1,000,000 | |
pension and other postretirement benefit plans, regulated assets, net gains, before tax | | | | 20,400,000 | 35,900,000 | |
Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax | | | | 200,000 | 500,000 | |
Pension and other postretirement benefit plans, regulatory assets, before tax | | | | 20,600,000 | 36,400,000 | |
Defined Benefit Plan, Shared Costs Deferred | | | | 13.8 | 15.1 | |
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax | | | | $ (14,000,000) | $ 15,800,000 | $ (24,400,000) |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | | | | 4.30% | 5.19% | 4.19% |
Defined Benefit Plan, Amounts Funded to Parent | | | | $ (2,100,000) | $ (1,400,000) | |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | | | | 3.00% | 3.75% | 3.75% |
Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax | | | | $ (1,500,000) | $ 0 | $ (2,200,000) |
Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax | | | | (300,000) | (200,000) | (500,000) |
Regulatory assets, prior service cost (credit), pension and other postretirement benefit plans, net of tax | | | | 0 | 0 | 0 |
Regulatory assets, amortization of transition obligation, pension and other postretirement benefit plans, net of tax | | | | 0 | 0 | (100,000) |
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax | | | | (15,800,000) | (15,600,000) | (27,200,000) |
SCE&G | Pension Plan, Defined Benefit | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Adoption of new mortality tables in 2014, gain | | | | | 22,000,000 | |
Adoption of modified mortality tables in 2015, gain | | | | 18,200,000 | | |
Defined Benefit Plan, Benefit Obligation | 695,700,000 | | | 724,000,000 | 773,700,000 | 695,700,000 |
Service cost | | | | 19,300,000 | 16,000,000 | 17,600,000 |
Interest cost | | | | 32,200,000 | 34,100,000 | 32,600,000 |
Defined Benefit Plan, Contributions by Plan Participants | | | | 0 | 0 | |
Defined Benefit Plan, Actuarial Net (Gains) Losses | | | | 47,000,000 | (82,700,000) | |
Defined Benefit Plan, Benefits Paid | | | | (54,200,000) | (54,800,000) | |
Defined Benefit Plan, Curtailments | | | | $ 0 | $ 0 | 8,400,000 |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | | | | 4.68% | 4.20% | |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase | | | | 3.00% | 3.00% | |
Defined Benefit Plan, Fair Value of Plan Assets | $ 792,100,000 | | | $ 720,100,000 | $ 783,600,000 | 792,100,000 |
Defined Benefit Plan, Funded Status of Plan | | | | (3,900,000) | 9,900,000 | |
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent | | | | 0 | 9,900,000 | |
Defined Benefit Pension Plan, Liabilities, Noncurrent | | | | | 0 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax | | | | 2,000,000 | 1,900,000 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax | | | | 0 | 100,000 | |
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax | | | | 2,000,000 | 2,000,000 | |
pension and other postretirement benefit plans, regulated assets, net gains, before tax | | | | 193,700,000 | 191,900,000 | |
Pension and other postretirement benefit plans, regulatory assets, net prior service costs (credit), before tax | | | | 5,200,000 | 8,300,000 | |
Pension and other postretirement benefit plans, regulatory assets, before tax | | | | 198,900,000 | 200,200,000 | |
Defined Benefit Plan, Shared Costs Deferred | | | | 20.3 | 17.8 | |
Regulatory assets, pension and other postretirement benefit plans, net unamortized gain (loss) arising during the period, net of tax | | | | $ 12,200,000 | $ 87,700,000 | (137,100,000) |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | 5.07% | 4.10% | | 4.20% | 5.03% | |
Defined Benefit Plan, Amounts Funded to Parent | | | | $ 0 | $ 0 | |
Expected return on assets | | | | (52,200,000) | (56,300,000) | (51,900,000) |
Defined Benefit Plan, Actual Return on Plan Assets | | | | $ (9,300,000) | $ 46,300,000 | |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | 3.00% | 3.75% | | 3.00% | 3.00% | |
Regulatory assets, amortization of actuarial losses, pension and other postretirement benefit plans, net of tax | | | | $ (10,400,000) | $ (3,500,000) | (12,700,000) |
Regulatory assets, amortization of prior service cost, pension and other postretirement benefit plans, net of tax | | | | (3,100,000) | (2,800,000) | (4,500,000) |
Regulatory assets, prior service cost (credit), pension and other postretirement benefit plans, net of tax | | | | 0 | 0 | (7,700,000) |
Regulatory assets, amortization of transition obligation, pension and other postretirement benefit plans, net of tax | | | | 0 | 0 | 0 |
Regulatory assets, total recognized in regulatory assets, pension and other postretirement benefit plans, net of tax | | | | (1,300,000) | $ (81,400,000) | (162,000,000) |
Pension Costs [Member] | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Defined Benefit Plan, Deferred Debit Attributable to Share of Regulatory Authority | $ 63,000,000 | | | 14,000,000 | | 63,000,000 |
Pension Costs [Member] | SCE&G | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Defined Benefit Plan, Deferred Debit Attributable to Share of Regulatory Authority | $ 63,000,000 | | | $ 14,000,000 | | $ 63,000,000 |
Regulatory assets, expected recovery period (in years) | | | | 12 years | | 14 years |
Scenario, Forecast [Member] | Other Postretirement Benefits | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Defined benefit plan, future amortization of gain or loss from regulatory assets | | | $ 300,000 | | | |
Defined benefit plan, future amortization of prior service cost (credit) from regulatory assets | | | 300,000 | | | |
Defined benefit plan, amount to be amortized from regulatory assets next year | | | 600,000 | | | |
Scenario, Forecast [Member] | Pension Plan, Defined Benefit | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Defined benefit plan, future amortization of gain or loss from regulatory assets | | | 12,700,000 | | | |
Defined benefit plan, future amortization of prior service cost (credit) from regulatory assets | | | 3,400,000 | | | |
Defined benefit plan, amount to be amortized from regulatory assets next year | | | $ 16,100,000 | | | |
Scenario, Forecast [Member] | SCE&G | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year | | | insignificant | | | |
Scenario, Forecast [Member] | SCE&G | Other Postretirement Benefits | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Defined benefit plan, future amortization of gain or loss from regulatory assets | | | $ 300,000 | | | |
Defined benefit plan, future amortization of prior service cost (credit) from regulatory assets | | | 200,000 | | | |
Defined benefit plan, amount to be amortized from regulatory assets next year | | | 500,000 | | | |
Scenario, Forecast [Member] | SCE&G | Pension Plan, Defined Benefit | | | | | | |
Defined Benefit Plan Disclosure [Line Items] | | | | | | |
Defined benefit plan, future amortization of gain or loss from regulatory assets | | | 11,200,000 | | | |
Defined benefit plan, future amortization of prior service cost (credit) from regulatory assets | | | 3,000,000 | | | |
Defined benefit plan, amount to be amortized from regulatory assets next year | | | $ 14,200,000 | | | |