Business Segments (Schedule of Segment Reporting Information, by Segment) (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
|
| Segment Reporting Information [Line Items] | ||
| Segment income | $ 716 | $ 574 |
| Duke Energy Carolinas [Member] | Other [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Segment income | (6) | (17) |
| Progress Energy [Member] | Other [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Segment income | (43) | (49) |
| Duke Energy Progress [Member] | Other [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Segment income | (3) | (8) |
| Duke Energy Florida [Member] | Other [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Segment income | (2) | (4) |
| Duke Energy Ohio [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Segment income | 42 | 57 |
| Duke Energy Indiana [Member] | Other [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Segment income | (2) | (2) |
| Piedmont Natural Gas [Member] | Other [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Segment income | $ (4) | $ 6 |