Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2011

Contributions To Defined Pension Plans

	For the Years Ended December 31,
	2012		2011		2010		2009
	(in millions)
Contributions made			$	200	$	400	$	800
Anticipated contributions	$	200

Other Changes In Plan Assets And Projected Benefit Obligations Recognized In Accumulated Other Comprehensive Income And Regulatory Assets

	For the Years Ended December 31,
	2011			2010
	(in millions)
Regulatory assets, net increase	$	152		$	350
Accumulated other comprehensive (income) loss(a)
Deferred income tax asset		(10	)		143
Actuarial losses (gains) arising during the year		60			(5	)
Amortization of prior year actuarial losses		(8	)		(16	)
Reclassification of actuarial gains (losses) to regulatory assets		8			(365	)
Amortization of prior year prior service cost		(1	)		(3	)
Reclassification of prior service cost to regulatory assets		—			(19	)
Net amount recognized in accumulated other comprehensive (income) loss	$	49		$	(265	)

Assumed Health Care Cost Trend Rates

	2011			2010
Health care cost trend rate assumed for next year		8.75	%		8.50	%
Rate to which the cost trend is assumed to decline (the ultimate trend rate)		5.00	%		5.00	%
Year that the rate reaches the ultimate trend rate		2020			2020

Sensitivity To Changes In Assumed Health Care Cost Trend Rates

	1-Percentage- Point Increase		1-Percentage- Point Decrease
	(in millions)
Effect on total service and interest costs	$	2	$	(2	)
Effect on post-retirement benefit obligation		31		(28	)

Expected Benefit Payments

	Qualified Plans		Non-Qualified Plans		Other  Post- Retirement Plans(a)		Total
			(in millions)
Years Ended December 31,
2012	$	463	$	17	$	49	$	529
2013		451		15		52		518
2014		440		17		53		510
2015		434		14		54		502
2016		428		13		55		496
2017 – 2021		2,050		64		270		2,384

(a) Duke Energy expects to receive future subsidies under Medicare Part D of $4 million in 2012 and $3 million in each of the years 2013-2016, and a total of $15 million during the years 2017-2021.

Weighted Average Returns Expected

Asset Class	Weighted- average returns expected
U.S. Equities		2.61	%
Non-U.S. Equities		1.50	%
Global Equities		0.99	%
Debt Securities		1.69	%
Global Private Equity		0.37	%
Hedge Funds		0.24	%
Real Estate		0.30	%
Other Global Securities		0.30	%

Target And Actual Asset Allocations

Asset Category	Target Allocation			Percentage at December  31,
				2011			2010
U.S. equity securities		28	%		28	%		30	%
Non-U.S. equity securities		15			15			19
Global equity securities		10			9			10
Debt securities		32			32			27
Global private equity securities		3			1			—
Hedge funds		4			3			3
Real estate and cash		4			9			7
Other global securities		4			3			4
Total		100	%		100	%		100	%

Summary Of Fair Value Measurements

	Total Fair Value Amounts at December 31, 2011(a)		Level 1		Level 2		Level 3
	(in millions)
Master Trust
Equity securities	$	2,568	$	1,745	$	823	$	—
Corporate bonds		1,237		—		1,236		1
Short-term investment funds		328		276		52		—
Partnership interests		127		—		—		127
Hedge funds		89		—		89		—
Real estate investment trust		152		—		—		152
U.S. Government securities		211		—		211		—
Other investments(b)		33		30		2		1
Guaranteed investment contracts		39		—		—		39
Government bonds—Foreign		39		—		38		1
Cash		7		7		—		—
Asset backed securities		4		—		3		1
Government and commercial mortgage backed securities		8		—		8		—
Total Assets	$	4,842	$	2,058	$	2,462	$	322

(a) Excludes $27 million in net receivables and payables associated with security purchases and sales.

(b) Includes pending investment sales (net of investment purchases) of $3 million.

The following table provides the fair value measurement amounts for Master Trust qualified pension and other post-retirement assets at December 31, 2010:

	Total Fair Value Amounts at December 31, 2010(a)			Level 1			Level 2		Level 3
	(in millions)
Master Trust
Equity securities	$	2,978		$	2,019		$	959	$	—
Corporate bonds		1,062			11			1,040		11
Short-term investment funds		484			469			15		—
Partnership interests		108			—			—		108
Hedge funds		94			—			94		—
Real estate investment trust		66			—			—		66
U.S. Government securities		138			—			138		—
Other investments(b)		(121	)		(84	)		3		(40	)
Guaranteed investment contracts		38			—			—		38
Government bonds—Foreign		35			—			34		1
Cash		2			2			—		—
Asset backed securities		9			—			8		1
Government and commercial mortgage backed securities		8			—			8		—
Total Assets	$	4,901		$	2,417		$	2,299	$	185

(a) Excludes $23 million in net receivables and payables associated with security purchases and sales.

(b) Includes pending investment sales (net of investment purchases) of $(139) million.

Schedule Of Effect Of Significant Unobservable Inputs Changes In Plan Assets

Master Trust
Year Ended December 31, 2011 (in million)
Balance at January 1, 2011	$	185
Purchases, sales, issuances and settlements:
Purchases		156
Sales		(29	)
Total gains (losses), (realized and unrealized) and other		10
Balance at December 31, 2011	$	322

The following table provides a reconciliation of beginning and ending balances of Master Trust assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3) for the year ended December 31, 2010:

Master Trust
Year Ended December 31, 2010 (in million)
Balance at January 1, 2010	$	256
Purchases, sales, issuances and settlements (net)		(71	)
Total gains (losses), realized and unrealized and other		—
Balance at December 31, 2010	$	185

Qualified Pension Plans [Member]

Components Of Net Periodic Pension Costs

	For the Years Ended December 31,
	2011(a)			2010(a)			2009(a)
	(in millions)
Service cost	$	96		$	96		$	85
Interest cost on projected benefit obligation		232			248			257
Expected return on plan assets		(384	)		(378	)		(362	)
Amortization of prior service cost		6			5			7
Amortization of actuarial loss		77			50			2
Settlement and contractual termination benefit cost		—			13			—
Other		18			18			17
Net periodic pension costs	$	45		$	52		$	6

(a) These amounts exclude $14 million, $16 million and $10 million for the years ended December 31, 2011, 2010 and 2009, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.

Schedule Of Changes In Projected Benefit Obligations

	As of and for the Years Ended December 31,
	2011			2010
	(in millions)
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	4,861		$	4,695
Service cost		96			96
Interest cost		232			248
Actuarial (gains) losses		(7	)		190
Plan amendments		18			2
Settlement and contractual termination benefit cost		—			13
Benefits paid		(320	)		(383	)
Obligation at measurement date	$	4,880		$	4,861

Schedule Of Changes In Fair Value Of Plan Assets

	As of and for the Years Ended December 31,
	2011			2010
	(in millions)
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	4,797		$	4,224
Actual return on plan assets		64			556
Benefits paid		(320	)		(383	)
Employer contributions		200			400
Plan assets at measurement date	$	4,741		$	4,797

Schedule Of Amounts Recognized In Consolidated Balance Sheets

	As of December 31,
	2011			2010
	(in millions)
Prefunded pension cost	$	—		$	101
Accrued pension liability		(139	)		(165	)
Net amount recognized	$	(139	)	$	(64	)

Summary Of Accumulated Other Comprehensive Income

	As of December 31,
	2011			2010
	(in millions)
Regulatory assets	$	1,411		$	1,259
Accumulated other comprehensive (income) loss
Deferred income tax asset		(73	)		(63	)
Prior service cost		4			5
Net actuarial loss		201			141
Net amount recognized in accumulated other comprehensive (income) loss(a)	$	132		$	83

(a) Excludes accumulated other comprehensive income of $19 million and $17 million as of December 31, 2011 and 2010, respectively, net of tax, associated with a Brazilian retirement plan.

Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets

	As of December 31,
	2011		2010
	(in millions)
Projected benefit obligation	$	—	$	1,052
Accumulated benefit obligation		—		956
Fair value of plan assets		—		951

Assumptions Used For Pension Benefits Accounting

	As of December 31,
Benefit Obligations	2011		2010		2009
	(percentages)
Discount rate		5.10		5.00		5.50
Salary increase (graded by age)		4.40		4.10		4.50
Net Periodic Benefit Cost	2011		2010		2009
Discount rate		5.00		5.50		6.50
Salary increase		4.10		4.50		4.50
Expected long-term rate of return on plan assets		8.25		8.50		8.50

Non-Qualified Pension Plans [Member]

Components Of Net Periodic Pension Costs

	For the Years Ended December 31,
	2011		2010		2009
	(in millions)
Service cost	$	1	$	1	$	2
Interest cost on projected benefit obligation		8		9		10
Amortization of prior service cost		2		2		2
Settlement credit		—		—		(1	)
Net periodic pension costs	$	11	$	12	$	13

Other Changes In Plan Assets And Projected Benefit Obligations Recognized In Accumulated Other Comprehensive Income And Regulatory Assets

	For the Years Ended December 31,
	2011			2010
	(in millions)
Regulatory assets, net increase	$	2		$	23
Regulatory liabilities, net increase		7			3
Accumulated other comprehensive (income) loss
Deferred income tax asset		(1	)		8
Actuarial losses(gains) arising during the year		1			(8	)
Reclassification of actuarial losses to regulatory assets		—			(1	)
Amortization of prior year prior service cost		—			(2	)
Reclassification of prior services cost to regulatory assets		—			(1	)
Reclassification of prior services cost to regulatory liabilities		—			(8	)
Net amount recognized in accumulated other comprehensive (income) loss	$	—		$	(12	)

Schedule Of Changes In Projected Benefit Obligation And Fair Value Of Plan Assets

	As of and for the Years Ended December 31,
	2011			2010
	(in millions)
Change in Projected Benefit Obligation
Obligation at prior measurement date	$	167		$	173
Service cost		1			1
Interest cost		8			9
Actuarial losses (gains)		(2	)		2
Benefits paid		(14	)		(18	)
Obligation at measurement date	$	160		$	167
Change in Fair Value of Plan Assets
Benefits paid	$	(14	)	$	(18	)
Employer contributions		14			18
Plan assets at measurement date	$	—		$	—

Schedule Of Amounts Recognized In Consolidated Balance Sheets

	As of December 31,
	2011			2010
	(in millions)
Accrued pension liability(a)	$	(160	)	$	(167	)

(a) Includes $17 million and $19 million recognized in Other within Current Liabilities on the Consolidated Balance Sheets as of December 31, 2011 and 2010, respectively.

Summary Of Accumulated Other Comprehensive Income

	As of December 31,
	2011		2010
	(in millions)
Regulatory assets	$	25	$	23
Regulatory liabilities		10		3
Accumulated other comprehensive (income) loss
Deferred income tax (asset) liability		—		1
Prior service cost		—		1
Net actuarial loss (gain)		1		(1	)
Net amount recognized in accumulated other comprehensive (income) loss	$	1	$	1

Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets

	As of December 31,
	2011		2010
	(in millions)
Projected benefit obligation	$	160	$	167
Accumulated benefit obligation		151		160
Fair value of plan assets		—		—

Assumptions Used For Pension Benefits Accounting

	As of December 31,
Benefit Obligations	2011		2010		2009
	(percentages)
Discount rate		5.10		5.00		5.50
Salary increase (graded by age)		4.40		4.10		4.50
Net Periodic Benefit Cost	2011		2010		2009
Discount rate		5.00		5.50		6.50
Salary increase		4.10		4.50		4.50

Other Post-Retirement Benefit Plans [Member]

Components Of Net Periodic Pension Costs

	For the Years Ended December 31,
	2011(a)			2010(a)			2009(a)
	(in millions)
Service cost	$	7		$	7		$	7
Interest cost on accumulated post-retirement benefit obligation		35			38			46
Expected return on plan assets		(15	)		(15	)		(16	)
Amortization of prior service credit		(8	)		(8	)		(8	)
Amortization of net transition liability		10			11			10
Amortization of actuarial gain		(3	)		(5	)		(5	)
Net periodic other post-retirement benefit costs	$	26		$	28		$	34

(a) These amounts exclude $8 million, $9 million and $9 million for the years ended December 31, 2011, 2010 and 2009, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.

Other Changes In Plan Assets And Projected Benefit Obligations Recognized In Accumulated Other Comprehensive Income And Regulatory Assets

	For the Years Ended December 31,
	2011			2010
	(in millions)
Regulatory assets, net decrease	$	(22	)	$	(14	)
Regulatory liabilities, net increase (decrease)		21			(5	)
Accumulated other comprehensive (income) loss
Deferred income tax liability		1			1
Actuarial (gain) loss arising during the year		—			(3	)
Amortization of prior year actuarial gains		1			1
Reclassification of actuarial losses to regulatory liabilities		—			(8	)
Amortization of prior year prior service credit		—			2
Reclassification of prior service credit to regulatory liabilities		—			9
Amortization of prior year net transition liability		—			(2	)
Reclassification of net transition liability to regulatory liabilities		—			(2	)
Net amount recognized in accumulated other comprehensive (income) loss	$	2		$	(2	)

Schedule Of Changes In Projected Benefit Obligation And Fair Value Of Plan Assets

	As of and for the Years Ended December 31,
	2011			2010
	(in millions)
Change in Benefit Obligation
Accumulated post-retirement benefit obligation at prior measurement date	$	723		$	728
Service cost		7			7
Interest cost		35			38
Plan participants' contributions		32			35
Actuarial gain		(55	)		(12	)
Benefits paid		(83	)		(79	)
Early retiree reinsurance program subsidy		3			—
Accrued retiree drug subsidy		5			6
Accumulated post-retirement benefit obligation at measurement date	$	667		$	723
Change in Fair Value of Plan Assets
Plan assets at prior measurement date	$	186		$	169
Actual return on plan assets		4			19
Benefits paid		(83	)		(79	)
Employer contributions		42			42
Plan participants' contributions		32			35
Plan assets at measurement date	$	181		$	186

Schedule Of Amounts Recognized In Consolidated Balance Sheets

	As of December 31,
	2011			2010
	(in millions)
Accrued other post-retirement liability(a)	$	(486	)	$	(537	)

(a) Includes $3 million and $2 million recognized in Other within Current Liabilities on the Consolidated Balance Sheets as of December 31, 2011 and 2010, respectively.

Summary Of Accumulated Other Comprehensive Income

	As of December 31,
	2011			2010
	(in millions)
Regulatory assets	$	37		$	59
Regulatory liabilities		107			86
Accumulated other comprehensive (income)/loss:
Deferred income tax liability		4			3
Prior service credit		(3	)		(3	)
Net actuarial loss (gain)		(6	)		(7	)
Net amount recognized in accumulated other comprehensive (income)/loss	$	(5	)	$	(7	)

Assumptions Used For Pension Benefits Accounting

	As of December 31,
Determined Benefit Obligations	2011		2010		2009
	(percentages)
Discount rate		5.10		5.00		5.50
Net Periodic Benefit Cost	2011		2010		2009
Discount rate		5.00		5.50		6.50
Expected long-term rate of return on plan assets		5.36-8.25		5.53-8.50		5.53-8.50
Assumed tax rate(a)		35.0		35.0		35.0

(a) Applicable to the health care portion of funded post-retirement benefits.

V.E.B.A I And II [Member]

Summary Of Fair Value Measurements

	Total Fair Value Amounts at December 31, 2011		Level 1		Level 2		Level 3
	(in millions)
VEBA I
Cash and cash equivalents	$	26	$	—	$	26	$	—
Equity securities		11		—		11		—
Debt securities		16		—		16		—
Total Assets	$	53	$	—	$	53	$	—

The following table provides the fair value measurement amounts for VEBA I and VEBA II other post-retirement assets at December 31, 2010:

	Total Fair Value Amounts at December 31, 2010		Level 1		Level 2		Level 3
	(in millions)
VEBA I/II
Cash and cash equivalents	$	30	$	—	$	30	$	—
Equity securities		12		—		12		—
Debt securities		17		—		17		—
Total Assets	$	59	$	—	$	59	$	—

Veba I [Member]

Target And Actual Asset Allocations

VEBA I Asset Category	Target Allocation			Percentage at December 31,
				2011			2010
U.S. equity securities		30	%		20	%		22	%
Debt securities		45			31			34
Cash		25			49			44
Total		100	%		100	%		100	%

Veba II [Member]

Target And Actual Asset Allocations

VEBA II Asset Category	Target Allocation			Percentage at December 31,
				2011			2010
U.S. equity securities		—	%		—	%		1	%
Debt securities		—			—			69
Cash		—			—			30
Total		—	%		—	%		100	%