Fair Value Measurements (Quantitative Level 3 Fair Value Disclosure) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	$ (1)	$ 13	$ (85)	$ (39)
Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	(5)	(2)
Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per MMBtu	2.12	3.07
Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per MMBtu	4.35	5.37
FERC Mitigation Power Sale Agreements [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)		(2)
FERC Mitigation Power Sale Agreements [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh		25.79
FERC Mitigation Power Sale Agreements [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh		52.38
Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	14	12
Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh	(1.92)	(0.30)
Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh	9.86	13.80
Commodity Power Contracts [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	(1)	23
Commodity Power Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh	25.16	20.77
Commodity Power Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh	51.75	58.90
Commodity Capacity Option Contracts [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	2	4
Commodity Capacity Option Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per Mwd	21.00	30.40
Commodity Capacity Option Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per Mwd	109.00	165.10
Derivative Financial Instruments Liabilities Reserves [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	(11)	(22)
Duke Energy Carolinas [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)		(2)	(12)
Duke Energy Carolinas [Member] | FERC Mitigation Power Sale Agreements [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)		(2)
Duke Energy Carolinas [Member] | FERC Mitigation Power Sale Agreements [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh		25.79
Duke Energy Carolinas [Member] | FERC Mitigation Power Sale Agreements [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh		52.38
Progress Energy [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)			(38)	(24)
Duke Energy Progress [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)			(38)	(24)
Duke Energy Ohio [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	(18)	(4)	(6)	(3)
Duke Energy Ohio [Member] | Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	(5)	(2)
Duke Energy Ohio [Member] | Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per MMBtu	2.12	3.07
Duke Energy Ohio [Member] | Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per MMBtu	4.35	5.37
Duke Energy Ohio [Member] | Commodity Power Contracts [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	(6)	18
Duke Energy Ohio [Member] | Commodity Power Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh	25.25	20.77
Duke Energy Ohio [Member] | Commodity Power Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh	51.75	58.90
Duke Energy Ohio [Member] | Derivative Financial Instruments Liabilities Reserves [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	(7)	(20)
Duke Energy Indiana [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	14	12	10	4
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability)	$ 14	$ 12
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price FTR	(1.92)	(0.30)
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price FTR	9.86	13.80