Regulatory Matters (Schedule of MISO Exit fees)(Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Restructuring Reserve [Roll Forward]
Balance, beginning of period	$ 135
Cash reductions	(123)
Provision/adjustments	52
Balance, end of period	64
Total regulatory assets	10,086		11,741
Duke Energy Ohio [Member]
Restructuring Reserve [Roll Forward]
Total regulatory assets	528		625
Duke Energy Ohio [Member] | RTO Realignment [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	97
Cash reductions	(4)
Provision/adjustments	2
Balance, end of period	95	[1]
Total regulatory assets	$ 74

[1] As of December 31, 2013, $74 million is recorded as a Regulatory asset on Duke Energy Ohio's Consolidated Balance Sheets.