Acquisitions and Dispositions (Pro Forma Information) (Details) - Piedmont Natural Gas [Member] $ in Millions |
3 Months Ended |
|---|---|
|
Mar. 31, 2016
USD ($)
| |
| Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] | |
| Operating Revenues | $ 5,840 |
| Net income attributable to Duke Energy Corporation | $ 832 |