Severance (Rollforward) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Restructuring Reserve [Roll Forward]
Balance, beginning of period	$ 28
Provision/adjustments	144
Cash reductions	(36)
Balance, end of period	136
Duke Energy Carolinas [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	2
Provision/adjustments	80
Cash reductions	(4)
Balance, end of period	78
Progress Energy [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	18
Provision/adjustments	20
Cash reductions	(15)
Balance, end of period	23
Duke Energy Progress [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	1
Provision/adjustments	20
Cash reductions	(2)
Balance, end of period	19
Duke Energy Florida [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	17
Cash reductions	(13)
Balance, end of period	$ 4