Acquisitions, Dispositions and Sales of Other Assets (Accounting Charges) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Significant Acquisitions and Disposals [Line Items]
FERC mitigation	$ (15)		$ 117
Severance charges		34	201
Community support and charitable contributions and other		34	92
Progress Merger [Member]
Significant Acquisitions and Disposals [Line Items]
FERC mitigation			117
Severance charges			196
Community support and charitable contributions and other			169
Total charges related to the merger consummation			482
Duke Energy Carolinas [Member]
Significant Acquisitions and Disposals [Line Items]
FERC mitigation	3		46
Severance charges		8	63
Community support and charitable contributions and other		14	56
Duke Energy Carolinas [Member] | Progress Merger [Member]
Significant Acquisitions and Disposals [Line Items]
FERC mitigation			46
Severance charges			63
Community support and charitable contributions and other			79
Total charges related to the merger consummation			188
Progress Energy [Member]
Significant Acquisitions and Disposals [Line Items]
FERC mitigation	(18)		71
Severance charges		19	82
Community support and charitable contributions and other		20	36
Progress Energy [Member] | Progress Merger [Member]
Significant Acquisitions and Disposals [Line Items]
FERC mitigation			71
Severance charges			82
Community support and charitable contributions and other			74
Total charges related to the merger consummation			227
Duke Energy Progress [Member]
Significant Acquisitions and Disposals [Line Items]
FERC mitigation	(18)		71
Severance charges		14	55
Community support and charitable contributions and other		20	36
Duke Energy Progress [Member] | Progress Merger [Member]
Significant Acquisitions and Disposals [Line Items]
FERC mitigation			71
Severance charges			55
Community support and charitable contributions and other			63
Total charges related to the merger consummation			189
Duke Energy Florida [Member]
Significant Acquisitions and Disposals [Line Items]
Severance charges		5	27
Duke Energy Florida [Member] | Progress Merger [Member]
Significant Acquisitions and Disposals [Line Items]
Severance charges			27
Community support and charitable contributions and other			11
Total charges related to the merger consummation			38
Duke Energy Ohio [Member]
Significant Acquisitions and Disposals [Line Items]
Severance charges		2	21
Duke Energy Ohio [Member] | Progress Merger [Member]
Significant Acquisitions and Disposals [Line Items]
Severance charges			21
Community support and charitable contributions and other			7
Total charges related to the merger consummation			28
Duke Energy Indiana [Member]
Significant Acquisitions and Disposals [Line Items]
Severance charges		2	18
Duke Energy Indiana [Member] | Progress Merger [Member]
Significant Acquisitions and Disposals [Line Items]
Severance charges			18
Community support and charitable contributions and other			6
Total charges related to the merger consummation			$ 24