The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Business Segments (Narrative) (Details) $ in Millions	12 Months Ended
Business Segments (Narrative) (Details) $ in Millions	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Interest expense	$ 1,916	$ 1,527	$ 1,529
Duke Energy Carolinas [Member]
Segment Reporting Information [Line Items]
Number of reportable segments \| segment	1
Interest expense	$ 424	412	407
Progress Energy [Member]
Segment Reporting Information [Line Items]
Number of reportable segments \| segment	1
Interest expense	$ 689	670	675
Duke Energy Progress [Member]
Segment Reporting Information [Line Items]
Number of reportable segments \| segment	1
Interest expense	$ 257	235	234
Duke Energy Florida [Member]
Segment Reporting Information [Line Items]
Number of reportable segments \| segment	1
Interest expense	$ 212	198	201
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Number of reportable segments \| segment	2
Interest expense	$ 86	79	86
Duke Energy Indiana [Member]
Segment Reporting Information [Line Items]
Number of reportable segments \| segment	1
Interest expense	$ 181	176	171
Other Segment [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Interest expense	693	393	409
Other Segment [Member] \| Progress Energy [Member]
Segment Reporting Information [Line Items]
Interest expense	221	240	241
Other Segment [Member] \| Duke Energy Ohio [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Interest expense	$ 1	$ 1	$ 5
National Methanol Company [Member] \| Other [Member]
Segment Reporting Information [Line Items]
Equity method investment, ownership percentage	25.00%
National Methanol Company [Member] \| Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Equity method investment, ownership percentage	25.00%