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Employee Benefit Plans (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | $ 988 | $ 1,103
Regulatory assets | 15,622 | 13,879
Regulatory Liabilities | 15,432 | 15,732
Duke Energy Carolinas [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 99 | 95
Regulatory assets | 3,977 | 3,152
Regulatory Liabilities | 6,198 | 6,357
Progress Energy [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 521 | 545
Regulatory assets | 7,701 | 6,751
Regulatory Liabilities | 5,329 | 5,519
Duke Energy Progress [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 237 | 248
Regulatory assets | 4,814 | 3,859
Regulatory Liabilities | 4,133 | 4,138
Duke Energy Florida [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 254 | 264
Regulatory assets | 2,888 | 2,892
Regulatory Liabilities | 1,196 | 1,381
Duke Energy Ohio [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 79 | 59
Regulatory assets | 564 | 494
Regulatory Liabilities | 897 | 927
Duke Energy Indiana [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 115 | 76
Regulatory assets | 1,157 | 1,143
Regulatory Liabilities | 1,747 | 1,747
Piedmont Natural Gas [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 4 | 5
Regulatory assets | 357 | 378
Regulatory Liabilities | 1,218 | 1,144
Pension Plan [Member] | Qualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Prefunded pension | 433 | 680
Noncurrent pension liability | 69 | 125
Net amount recognized | 364 | 555
Regulatory assets | 2,184 | 1,886
Accumulated Other Comprehensive Income (Loss) [Abstract] |  |
Deferred income tax asset | (43) | (41)
Prior year service cost (credit) arising during the year | (4) | (5)
Net actuarial loss (gain) | 126 | 116
Net amount recognized in accumulated other comprehensive income (loss) | 79 | 70
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 97 | 132
Unrecognized prior service (credit) cost | (32) | (32)
Pension Plan [Member] | Nonqualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 21 | 23
Noncurrent pension liability | 283 | 308
Total accrued pension liability | 304 | 331
Regulatory assets | 62 | 78
Accumulated Other Comprehensive Income (Loss) [Abstract] |  |
Deferred income tax asset | (3) | (4)
Prior year service cost (credit) arising during the year | (1) | (1)
Net actuarial loss (gain) | 8 | 12
Net amount recognized in accumulated other comprehensive income (loss) | 4 | 7
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 6 | 8
Unrecognized prior service (credit) cost | (2) | (2)
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Prefunded pension | 214 | 343
Net amount recognized | 214 | 343
Regulatory assets | 576 | 406
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 22 | 29
Unrecognized prior service (credit) cost | (8) | (8)
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 2 | 2
Noncurrent pension liability | 12 | 12
Total accrued pension liability | 14 | 14
Regulatory assets | 5 | 4
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Prefunded pension | 242 | 245
Noncurrent pension liability | 69 | 68
Net amount recognized | 173 | 177
Regulatory assets | 796 | 756
Accumulated Other Comprehensive Income (Loss) [Abstract] |  |
Deferred income tax asset | (2) | (3)
Net actuarial loss (gain) | 5 | 9
Net amount recognized in accumulated other comprehensive income (loss) | 3 | 6
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 37 | 44
Unrecognized prior service (credit) cost | (3) | (3)
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 8 | 8
Noncurrent pension liability | 98 | 108
Total accrued pension liability | 106 | 116
Regulatory assets | 15 | 21
Accumulated Other Comprehensive Income (Loss) [Abstract] |  |
Deferred income tax asset | (2) | (3)
Net actuarial loss (gain) | 6 | 9
Net amount recognized in accumulated other comprehensive income (loss) | 4 | 6
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 2 | 2
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Prefunded pension | 143 | 155
Net amount recognized | 143 | 155
Regulatory assets | 372 | 341
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 13 | 21
Unrecognized prior service (credit) cost | (2) | (2)
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 3 | 3
Noncurrent pension liability | 28 | 32
Total accrued pension liability | 31 | 35
Regulatory assets | 5 | 8
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 1 | 1
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Prefunded pension | 96 | 87
Noncurrent pension liability | 69 | 68
Net amount recognized | 27 | 19
Regulatory assets | 424 | 415
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 24 | 23
Unrecognized prior service (credit) cost | (1) | (1)
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 3 | 3
Noncurrent pension liability | 40 | 44
Total accrued pension liability | 43 | 47
Regulatory assets | 10 | 13
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 1 | 1
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Prefunded pension | 24 | 8
Noncurrent pension liability | 54 | 29
Net amount recognized | (30) | (21)
Regulatory assets | 100 | 90
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 3 | 5
Pension Plan [Member] | Duke Energy Ohio [Member] | Nonqualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 3 | 4
Total accrued pension liability | 3 | 4
Regulatory assets | 1 | 1
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Prefunded pension | 39 | 16
Noncurrent pension liability | 46 | 1
Net amount recognized | (7) | 15
Regulatory assets | 182 | 152
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 5 | 7
Unrecognized prior service (credit) cost | (2) | (2)
Pension Plan [Member] | Duke Energy Indiana [Member] | Nonqualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 3 | 3
Total accrued pension liability | 3 | 3
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Prefunded pension | 41 | 55
Net amount recognized | 41 | 55
Regulatory assets | 81 | 73
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 7 | 11
Unrecognized prior service (credit) cost | (9) | (9)
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 3 | 4
Total accrued pension liability | 3 | 4
Regulatory assets | 1 | 1
Other Post-Retirement Benefit Plans [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 8 | 36
Noncurrent pension liability | 525 | 552
Total accrued pension liability | 533 | 588
Regulatory assets | 262 | 125
Regulatory Liabilities | 301 | 147
Accumulated Other Comprehensive Income (Loss) [Abstract] |  |
Deferred income tax liability | 3 | 4
Prior year service cost (credit) arising during the year | (2) | (2)
Net actuarial loss (gain) | (9) | (10)
Net amount recognized in accumulated other comprehensive income (loss) | (8) | (8)
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 4 | 5
Unrecognized prior service (credit) cost | (19) | (19)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 59 | 56
Total accrued pension liability | 59 | 56
Regulatory Liabilities | 38 | 44
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 2 | 3
Unrecognized prior service (credit) cost | (5) | (5)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 5 | 29
Noncurrent pension liability | 298 | 313
Total accrued pension liability | 303 | 342
Regulatory assets | 262 | 129
Regulatory Liabilities | 149 |
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss | 1 | 1
Unrecognized prior service (credit) cost | (7) | (7)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 3 | 15
Noncurrent pension liability | 163 | 169
Total accrued pension liability | 166 | 184
Regulatory assets | 164 | 80
Regulatory Liabilities | 93 |
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized prior service (credit) cost | (1) | (1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 2 | 14
Noncurrent pension liability | 135 | 142
Total accrued pension liability | 137 | 156
Regulatory assets | 98 | 49
Regulatory Liabilities | 56 |
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized net actuarial loss |  | 1
Unrecognized prior service (credit) cost | (6) | (6)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Current pension liability | 2 | 2
Noncurrent pension liability | 19 | 21
Total accrued pension liability | 21 | 23
Regulatory Liabilities | 18 | 16
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized prior service (credit) cost | (1) | (1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 62 | 67
Total accrued pension liability | 62 | 67
Regulatory assets | 41 | 46
Regulatory Liabilities | 67 | 64
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized prior service (credit) cost | (1) | (1)
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member] |  |
Amounts Recognized in Consolidated Balance Sheets [Abstract] |  |
Noncurrent pension liability | 1 | 1
Total accrued pension liability | 1 | 1
Regulatory assets |  | (4)
Amounts to be recognized in net periodic pension expense in the next year [Abstract] |  |
Unrecognized prior service (credit) cost | $ (2) | $ (2)

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