Variable Interest Entities (Sales and Cash Flows)(Details) - Cinergy Receivables [Member] - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
|
| Duke Energy Ohio [Member] | ||
| Variable Interest Entities [Line Items] | ||
| Receivables sold | $ 533 | $ 532 |
| Loss recognized on sale | 2 | 3 |
| Cash proceeds from receivables sold | 559 | 537 |
| Return received on retained interests | 1 | 1 |
| Duke Energy Indiana [Member] | ||
| Variable Interest Entities [Line Items] | ||
| Receivables sold | 664 | 635 |
| Loss recognized on sale | 3 | 3 |
| Cash proceeds from receivables sold | 693 | 643 |
| Return received on retained interests | $ 2 | $ 1 |