Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2017

Defined Benefit Plan Disclosure [Line Items]

Defined Contribution Plan Disclosures

The following table presents employer contributions made by Duke Energy and expensed by the Subsidiary Registrants.

			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana		Piedmont
Three Months Ended June 30,
2017	$	39	$	13	$	12	$	8	$	4	$	1	$	2	$	1
2016	39		13		12		8		4		1		2		1
Six Months Ended June 30,
2017	$	104	$	35	$	30	$	21	$	9	$	2	$	5	$	3
2016	91		31		27		19		8		2		4		3

Qualified Pension Plan [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

The following tables include the components of net periodic pension costs for qualified pension plans.

	Three Months Ended June 30, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	40		$	12		$	12		$	6		$	5		$	1		$	2		$	3
Interest cost on projected benefit obligation	82			20			25			12			13			5			7			3
Expected return on plan assets	(136		)	(36		)	(43		)	(21		)	(21		)	(7		)	(11		)	(6		)
Amortization of actuarial loss	36			8			14			6			7			1			3			3
Amortization of prior service credit	(6		)	(2		)	(1		)	—			—			—			—			(1		)
Other	2			—			1			1			—			—			—			1
Net periodic pension costs	$	18		$	2		$	8		$	4		$	4		$	—		$	1		$	3

	Three Months Ended June 30, 2016
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	37		$	12		$	10		$	6		$	5		$	1		$	2		$	2
Interest cost on projected benefit obligation	83			22			27			13			14			5			7			3
Expected return on plan assets	(129		)	(36		)	(42		)	(20		)	(21		)	(7		)	(11		)	(6		)
Amortization of actuarial loss	33			8			13			5			7			1			3			2
Amortization of prior service credit	(4		)	(2		)	(1		)	(1		)	—			—			—			(1		)
Other	1			—			—			1			—			—			—			—
Net periodic pension costs	$	21		$	4		$	7		$	4		$	5		$	—		$	1		$	—

	Six Months Ended June 30, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	80		$	24		$	24		$	12		$	10		$	2		$	4		$	6
Interest cost on projected benefit obligation	164			40			50			24			26			10			14			6
Expected return on plan assets	(272		)	(71		)	(86		)	(42		)	(42		)	(14		)	(22		)	(12		)
Amortization of actuarial loss	72			16			28			12			14			2			6			6
Amortization of prior service credit	(12		)	(4		)	(2		)	—			—			—			—			(2		)
Other	4			—			2			1			—			—			—			1
Net periodic pension costs	$	36		$	5		$	16		$	7		$	8		$	—		$	2		$	5

	Six Months Ended June 30, 2016
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	73		$	24		$	21		$	12		$	10		$	2		$	4		$	5
Interest cost on projected benefit obligation	166			43			53			25			28			10			14			5
Expected return on plan assets	(258		)	(71		)	(84		)	(41		)	(42		)	(14		)	(21		)	(12		)
Amortization of actuarial loss	66			16			27			11			14			2			6			4
Amortization of prior service credit	(8		)	(4		)	(2		)	(1		)	—			—			—			(1		)
Other	4			1			1			1			—			—			—			—
Net periodic pension costs	$	43		$	9		$	16		$	7		$	10		$	—		$	3		$	1

Non-Qualified Pension Plan [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

The following tables include the components of net periodic pension costs for non-qualified pension plans for registrants with non-qualified pension costs.

	Three Months Ended June 30, 2017
			Duke				Duke		Duke
	Duke		Energy		Progress		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida
Service cost	$	—	$	—	$	—	$	—	$	—
Interest cost on projected benefit obligation	3		1		1		—		—
Amortization of actuarial loss	2		—		1		—		—
Net periodic pension costs	$	5	$	1	$	2	$	—	$	—

	Three Months Ended June 30, 2016
			Duke				Duke		Duke
	Duke		Energy		Progress		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida
Service cost	$	1	$	—	$	—	$	—	$	—
Interest cost on projected benefit obligation	3		1		1		1		1
Amortization of actuarial loss	2		—		—		—		—
Net periodic pension costs	$	6	$	1	$	1	$	1	$	1

	Six Months Ended June 30, 2017
			Duke				Duke		Duke
	Duke		Energy		Progress		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida
Service cost	$	—	$	—	$	—	$	—	$	—
Interest cost on projected benefit obligation	6		1		2		1		1
Amortization of actuarial loss	4		—		2		—		—
Net periodic pension costs	$	10	$	1	$	4	$	1	$	1

	Six Months Ended June 30, 2016
			Duke				Duke		Duke
	Duke		Energy		Progress		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida
Service cost	$	1	$	—	$	—	$	—	$	—
Interest cost on projected benefit obligation	7		1		2		1		1
Amortization of actuarial loss	4		—		1		—		—
Net periodic pension costs	$	12	$	1	$	3	$	1	$	1

Other Post-Retirement Benefit Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Components of Net Periodic Pension Costs

The following tables include the components of net periodic other post-retirement benefit costs.

	Three Months Ended June 30, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana		Piedmont
Service cost	$	1		$	—		$	—		$	—		$	—		$	—		$	—	$	—
Interest cost on accumulated post-retirement benefit obligation	9			2			3			2			2			—			—		—
Expected return on plan assets	(4		)	(2		)	—			—			—			—			—		—
Amortization of actuarial loss (gain)	2			(1		)	5			3			2			(1		)	—		—
Amortization of prior service credit	(29		)	(2		)	(21		)	(13		)	(7		)	—			—		—
Net periodic other post-retirement benefit costs	$	(21	)	$	(3	)	$	(13	)	$	(8	)	$	(3	)	$	(1	)	$	—	$	—

	Three Months Ended June 30, 2016
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	1		$	—		$	—		$	—		$	—		$	—		$	—		$	—
Interest cost on accumulated post-retirement benefit obligation	9			2			3			2			1			1			1			—
Expected return on plan assets	(4		)	(2		)	—			—			—			—			(1		)	—
Amortization of actuarial loss (gain)	2			(1		)	6			3			3			(1		)	—			—
Amortization of prior service credit	(36		)	(3		)	(25		)	(17		)	(9		)	—			—			—
Net periodic other post-retirement benefit costs	$	(28	)	$	(4	)	$	(16	)	$	(12	)	$	(5	)	$	—		$	—		$	—

	Six Months Ended June 30, 2017
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana		Piedmont
Service cost	$	2		$	—		$	—		$	—		$	—		$	—		$	—	$	—
Interest cost on accumulated post-retirement benefit obligation	18			4			7			4			4			—			—		—
Expected return on plan assets	(7		)	(4		)	—			—			—			—			—		—
Amortization of actuarial loss (gain)	4			(2		)	10			6			4			(1		)	—		—
Amortization of prior service credit	(58		)	(4		)	(42		)	(27		)	(15		)	—			—		—
Net periodic other post-retirement benefit costs	$	(41	)	$	(6	)	$	(25	)	$	(17	)	$	(7	)	$	(1	)	$	—	$	—

	Six Months Ended June 30, 2016
				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Service cost	$	2		$	—		$	—		$	—		$	—		$	—		$	—		$	—
Interest cost on accumulated post-retirement benefit obligation	17			4			7			4			3			1			2			1
Expected return on plan assets	(7		)	(4		)	—			—			—			—			(1		)	(1		)
Amortization of actuarial loss (gain)	3			(2		)	11			6			5			(1		)	(1		)	—
Amortization of prior service credit	(71		)	(6		)	(51		)	(34		)	(18		)	—			—			—
Net periodic other post-retirement benefit costs	$	(56	)	$	(8	)	$	(33	)	$	(24	)	$	(10	)	$	—		$	—		$	—