Asset Retirement Obligations (ARO Rollforward) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015 USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	$ 8,466
Acquisitions	9
Accretion expense	171
Liabilities settled	(187)
Liabilities incurred in the current year	983
Revision in estimates of cash flows	48
Balance at end of period	9,490
Duke Energy Carolinas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	3,428
Accretion expense	81
Liabilities settled	(60)
Liabilities incurred in the current year	178
Revision in estimates of cash flows	(23)
Balance at end of period	3,604
Progress Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	4,711
Accretion expense	97
Liabilities settled	(123)
Liabilities incurred in the current year	270
Revision in estimates of cash flows	40
Balance at end of period	4,995
Duke Energy Progress [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	3,905
Accretion expense	79
Liabilities settled	(32)
Liabilities incurred in the current year	270
Revision in estimates of cash flows	40
Balance at end of period	4,262
Duke Energy Florida [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	806
Accretion expense	18
Liabilities settled	(91)
Balance at end of period	733
Duke Energy Ohio [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	27
Accretion expense	1
Liabilities settled	(1)
Liabilities incurred in the current year	116
Balance at end of period	143
Duke Energy Indiana [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	32
Accretion expense	6
Liabilities settled	(3)
Liabilities incurred in the current year	418
Balance at end of period	$ 453