Asset Retirement Obligations (ARO Rollforward) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	$ 10,467
Accretion expense	245
Liabilities settled	(404)
Revision in estimates of cash flows	2,320
Balance at end of period	12,628
Duke Energy Carolinas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	3,949
Accretion expense	111
Liabilities settled	(155)
Revision in estimates of cash flows	1,437
Balance at end of period	5,342
Progress Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	5,411
Accretion expense	124
Liabilities settled	(225)
Revision in estimates of cash flows	883
Balance at end of period	6,193
Duke Energy Progress [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	4,820
Accretion expense	111
Liabilities settled	(197)
Revision in estimates of cash flows	882
Balance at end of period	5,616
Duke Energy Florida [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	591
Accretion expense	13
Liabilities settled	(28)
Revision in estimates of cash flows	1
Balance at end of period	577
Duke Energy Ohio [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	93
Accretion expense	2
Liabilities settled	(6)
Balance at end of period	89
Duke Energy Indiana [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	722
Accretion expense	14
Liabilities settled	(17)
Balance at end of period	719
Piedmont Natural Gas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	19
Balance at end of period	$ 19