Asset Retirement Obligations (ARO Rollforward) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	$ 10,264
Accretion expense	290
Liabilities settled	(443)
Liabilities incurred in the current year	13
Revision in estimates of cash flows	706
Balance at end of period	10,830
Duke Energy Carolinas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	3,918
Accretion expense	141
Liabilities settled	(204)
Revision in estimates of cash flows	70
Balance at end of period	3,925
Progress Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	5,369
Accretion expense	171
Liabilities settled	(203)
Liabilities incurred in the current year	3
Revision in estimates of cash flows	317
Balance at end of period	5,657
Duke Energy Progress [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	4,567
Accretion expense	144
Liabilities settled	(163)
Liabilities incurred in the current year	3
Revision in estimates of cash flows	308
Balance at end of period	4,859
Duke Energy Florida [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	802
Accretion expense	28
Liabilities settled	(41)
Revision in estimates of cash flows	9
Balance at end of period	798
Duke Energy Ohio [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	125
Accretion expense	4
Liabilities settled	(4)
Revision in estimates of cash flows	(17)
Balance at end of period	108
Duke Energy Indiana [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	525
Accretion expense	16
Liabilities settled	(31)
Revision in estimates of cash flows	337
Balance at end of period	$ 847