Regulatory Matters (Refunds) (Details) (Duke Energy Florida [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Florida Public Service Commission Settlement Agreement 2012 [Member]
Regulatory Assets Liabilities [Line Items]
Customer refunds to date	$ 129
2014	139
2015	10
2016	10
Total Customer Refunds To Be Paid	288	[1]
Retirement Decision Credits [Member]
Regulatory Assets Liabilities [Line Items]
2015	40
2016	60
Total Customer Refunds To Be Paid	100
Neil Settlement [Member]
Regulatory Assets Liabilities [Line Items]
Customer refunds to date	326
2014	164
Total Customer Refunds To Be Paid	490
Total Customer Refunds [Member]
Regulatory Assets Liabilities [Line Items]
Customer refunds to date	455
2014	303
2015	50
2016	70
Total Customer Refunds To Be Paid	878
Accelerated Regulatory Asset Recovery [Member]
Regulatory Assets Liabilities [Line Items]
2014	(37)
2015	(37)
2016	(56)
Total Customer Refunds To Be Paid	(130)
Net Customer Refunds [Member]
Regulatory Assets Liabilities [Line Items]
Customer refunds to date	455
2014	266
2015	13
2016	14
Total Customer Refunds To Be Paid	$ 748

[1] See discussion under Customer Rate Matters section below.