Asset Retirement Obligations (ARO Rollforward) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	$ 10,467
Accretion expense	377
Liabilities settled	(691)
Revision in estimates of cash flows	2,448
Balance at end of period	12,601
Duke Energy Carolinas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	3,949
Accretion expense	173
Liabilities settled	(276)
Revision in estimates of cash flows	1,552
Balance at end of period	5,398
Progress Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	5,411
Accretion expense	190
Liabilities settled	(375)
Revision in estimates of cash flows	862
Balance at end of period	6,088
Duke Energy Progress [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	4,820
Accretion expense	171
Liabilities settled	(341)
Revision in estimates of cash flows	864
Balance at end of period	5,514
Duke Energy Florida [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	591
Accretion expense	19
Liabilities settled	(34)
Revision in estimates of cash flows	(2)
Balance at end of period	574
Duke Energy Ohio [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	93
Accretion expense	3
Liabilities settled	(9)
Revision in estimates of cash flows	(2)
Balance at end of period	85
Duke Energy Indiana [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	722
Accretion expense	21
Liabilities settled	(32)
Revision in estimates of cash flows	113
Balance at end of period	824
Piedmont Natural Gas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	19
Accretion expense	1
Balance at end of period	$ 20