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Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Pension Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Amortization of Regulatory Asset | $ 4 | $ 5 | $ 7
Pension Plan | Qualified Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 158 | 182 |
Service cost | 150 | 174 | 159
Interest cost | 317 | 299 | 328
Expected return on plan assets | (567) | (559) | (545)
Amortization of actuarial loss (gain) | 108 | 132 | 146
Amortization of prior service cost (credit) | (32) | (32) | (24)
Settlement charge |  |  | 12
Other | 6 |  | 8
Net periodic costs | (10) | 22 | 84
Pension Plan | Duke Energy Carolinas | Qualified Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 49 | 58 |
Service cost | 47 | 56 | 48
Interest cost | 75 | 72 | 79
Expected return on plan assets | (147) | (147) | (142)
Amortization of actuarial loss (gain) | 24 | 29 | 31
Amortization of prior service cost (credit) | (8) | (8) | (8)
Settlement charge |  |  | 0
Other | 2 |  | 2
Net periodic costs | (5) | 4 | 10
Pension Plan | Progress Energy | Qualified Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 46 | 51 |
Service cost | 43 | 49 | 45
Interest cost | 100 | 94 | 100
Expected return on plan assets | (178) | (178) | (167)
Amortization of actuarial loss (gain) | 39 | 44 | 52
Amortization of prior service cost (credit) | (3) | (3) | (3)
Settlement charge |  |  | 0
Other | 1 |  | 2
Net periodic costs | 5 | 8 | 29
Pension Plan | Duke Energy Progress | Qualified Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 26 | 29 |
Service cost | 25 | 28 | 26
Interest cost | 45 | 43 | 47
Expected return on plan assets | (88) | (85) | (82)
Amortization of actuarial loss (gain) | 15 | 21 | 23
Amortization of prior service cost (credit) | (2) | (2) | (2)
Settlement charge |  |  | 0
Other | 1 |  | 1
Net periodic costs | (3) | 6 | 13
Pension Plan | Duke Energy Florida | Qualified Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 20 | 22 |
Service cost | 18 | 21 | 19
Interest cost | 54 | 50 | 53
Expected return on plan assets | (89) | (91) | (85)
Amortization of actuarial loss (gain) | 24 | 23 | 29
Amortization of prior service cost (credit) | (1) | (1) | (1)
Settlement charge |  |  | 0
Other | 0 |  | 1
Net periodic costs | 8 | 3 | 16
Pension Plan | Duke Energy Ohio |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Amortization of Regulatory Asset | 2 | 2 | 3
Pension Plan | Duke Energy Ohio | Qualified Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 4 | 5 |
Service cost | 4 | 5 | 4
Interest cost | 18 | 17 | 18
Expected return on plan assets | (28) | (28) | (27)
Amortization of actuarial loss (gain) | 4 | 5 | 5
Amortization of prior service cost (credit) | 0 | 0 | (1)
Settlement charge |  |  | 0
Other | 2 |  | 0
Net periodic costs | 0 | (1) | (1)
Pension Plan | Duke Energy Indiana | Qualified Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 9 | 11 |
Service cost | 8 | 10 | 9
Interest cost | 26 | 23 | 26
Expected return on plan assets | (43) | (42) | (42)
Amortization of actuarial loss (gain) | 8 | 10 | 12
Amortization of prior service cost (credit) | (2) | (2) | (2)
Settlement charge |  |  | 0
Other | 0 |  | 1
Net periodic costs | (2) | 0 | 4
Pension Plan | Piedmont | Qualified Plan |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 5 | 7 |
Service cost | 5 | 7 | 10
Interest cost | 10 | 11 | 14
Expected return on plan assets | (22) | (22) | (24)
Amortization of actuarial loss (gain) | 8 | 11 | 11
Amortization of prior service cost (credit) | (9) | (10) | (2)
Settlement charge |  |  | 12
Other | 0 |  | 1
Net periodic costs | (8) | (3) | 22
Other Post-Retirement Benefit Plans |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 4 | 6 | 4
Interest cost | 30 | 28 | 34
Expected return on plan assets | (12) | (13) | (14)
Amortization of actuarial loss (gain) | 4 | 6 | 10
Amortization of prior service cost (credit) | (19) | (19) | (115)
Curtailment credit |  |  | (30)
Net periodic costs | 7 | 8 | (111)
Amortization of Regulatory Asset | 6 | 7 | 7
Other Post-Retirement Benefit Plans | Duke Energy Carolinas |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 1 | 1 | 1
Interest cost | 7 | 7 | 8
Expected return on plan assets | (7) | (8) | (8)
Amortization of actuarial loss (gain) | 2 | 3 | (2)
Amortization of prior service cost (credit) | (5) | (5) | (10)
Curtailment credit |  |  | (4)
Net periodic costs | (2) | (2) | (15)
Other Post-Retirement Benefit Plans | Progress Energy |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 1 | 1 | 0
Interest cost | 12 | 12 | 13
Expected return on plan assets | 0 | 0 | 0
Amortization of actuarial loss (gain) | 1 | 1 | 21
Amortization of prior service cost (credit) | (8) | (8) | (84)
Curtailment credit |  |  | (16)
Net periodic costs | 6 | 6 | (66)
Other Post-Retirement Benefit Plans | Duke Energy Progress |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 0 | 0 | 0
Interest cost | 7 | 6 | 7
Expected return on plan assets | 0 | 0 | 0
Amortization of actuarial loss (gain) | 0 | 1 | 12
Amortization of prior service cost (credit) | (1) | (1) | (54)
Net periodic costs | 6 | 6 | (35)
Other Post-Retirement Benefit Plans | Duke Energy Florida |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 1 | 1 | 0
Interest cost | 5 | 6 | 6
Expected return on plan assets | 0 | 0 | 0
Amortization of actuarial loss (gain) | 1 | 0 | 9
Amortization of prior service cost (credit) | (7) | (7) | (30)
Curtailment credit |  |  | (16)
Net periodic costs | 0 | 0 | (31)
Other Post-Retirement Benefit Plans | Duke Energy Ohio |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 0 | 1 | 0
Interest cost | 1 | 1 | 1
Expected return on plan assets | 0 | 0 | 0
Amortization of actuarial loss (gain) | 0 | 0 | (2)
Amortization of prior service cost (credit) | (1) | (1) | 0
Curtailment credit |  |  | (2)
Net periodic costs | 0 | 1 | (3)
Amortization of Regulatory Asset | 2 | 2 | 2
Other Post-Retirement Benefit Plans | Duke Energy Indiana |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 1 | 1 | 0
Interest cost | 3 | 3 | 3
Expected return on plan assets | 0 | 0 | (1)
Amortization of actuarial loss (gain) | 4 | 4 | (1)
Amortization of prior service cost (credit) | (1) | (1) | (1)
Curtailment credit |  |  | (2)
Net periodic costs | 7 | 7 | (2)
Other Post-Retirement Benefit Plans | Piedmont |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |
Service cost | 0 | 1 | 1
Interest cost | 1 | 1 | 1
Expected return on plan assets | (1) | (2) | (2)
Amortization of actuarial loss (gain) | 0 | 0 | 1
Amortization of prior service cost (credit) | (2) | (2) | 0
Curtailment credit |  |  | 0
Net periodic costs | $ (2) | $ (2) | $ 1

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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from event reducing expected years of future service of present employees or eliminating accrual of defined benefits for some or all future services of present employees. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(7) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
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