Fair Value Measurements (Quantitative Level 3 Fair Value Disclosure) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) $ / MWh	Dec. 31, 2014 USD ($) $ / MWh	Dec. 31, 2013 USD ($)
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 10	$ (1)	$ 13
Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (5)
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
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
Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 10	$ 14
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	(0.74)	(1.92)
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	7.29	9.86
Commodity Power Contracts [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (1)
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
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
Commodity Capacity Option Contracts [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ 2
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
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
Derivative Financial Instruments Liabilities Reserves [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (11)
Duke Energy Carolinas [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $			(2)
Duke Energy Ohio [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 3	(18)	(4)
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)
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
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
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 3
Duke Energy Ohio [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	0.67
Duke Energy Ohio [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	2.53
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)
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
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
Duke Energy Ohio [Member] | Derivative Financial Instruments Liabilities Reserves [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (7)
Duke Energy Indiana [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 7	14	$ 12
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) | $	$ 7	$ 14
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	(0.74)	(1.92)
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	7.29	9.86