Asset Retirement Obligations (ARO Rollforward) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	$ 10,467
Accretion expense	110
Liabilities settled	(184)
Revision in estimates of cash flows	2,642
Balance at end of period	13,035
Duke Energy Carolinas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	3,949
Accretion expense	48
Liabilities settled	(76)
Revision in estimates of cash flows	1,507
Balance at end of period	5,428
Progress Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	5,411
Accretion expense	57
Liabilities settled	(97)
Revision in estimates of cash flows	1,135
Balance at end of period	6,506
Duke Energy Progress [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	4,820
Accretion expense	50
Liabilities settled	(82)
Revision in estimates of cash flows	1,135
Balance at end of period	5,923
Duke Energy Florida [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	591
Accretion expense	7
Liabilities settled	(15)
Balance at end of period	583
Duke Energy Ohio [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	93
Accretion expense	1
Liabilities settled	(1)
Balance at end of period	93
Duke Energy Indiana [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	722
Accretion expense	7
Liabilities settled	(10)
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