Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2018

Asset Retirement Obligation [Abstract]

Schedule of Asset Retirement Obligations

The following table presents the AROs recorded on the Condensed Consolidated Balance Sheets.

	June 30, 2018
			Duke				Duke		Duke		Duke		Duke
	Duke		Energy		Progress		Energy		Energy		Energy		Energy
(in millions)	Energy		Carolinas		Energy		Progress		Florida		Ohio		Indiana		Piedmont
Decommissioning of Nuclear Power Facilities(a)	$	5,319	$	2,002	$	3,158	$	2,621	$	536	$	—	$	—	$	—
Closure of Ash Impoundments	4,843		1,761		2,202		2,178		24		44		836		—
Other	307		56		78		36		42		45		20		15
Total ARO	$	10,469	$	3,819	$	5,438	$	4,835	$	602	$	89	$	856	$	15
Less: current portion	716		227		386		381		5		5		98		—
Total noncurrent ARO	$	9,753	$	3,592	$	5,052	$	4,454	$	597	$	84	$	758	$	15

(a)    Duke Energy amount includes purchase accounting adjustments related to the merger with Progress Energy.

Schedule of Change in Asset Retirement Obligation

The following table presents the change in liability associated with AROs for the Duke Energy Registrants.

				Duke						Duke			Duke			Duke			Duke
	Duke			Energy			Progress			Energy			Energy			Energy			Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio			Indiana			Piedmont
Balance at December 31, 2017(a)	$	10,175		$	3,610		$	5,414		$	4,673		$	742		$	84		$	781		$	15
Accretion expense(b)	212			89			113			97			16			2			14			—
Liabilities settled(c)	(245		)	(114		)	(108		)	(89		)	(19		)	(2		)	(21		)	—
Liabilities incurred in the current year	8			8			—			—			—			—			—			—
Revisions in estimates of cash flows(d)	319			226			19			154			(137		)	5			82			—
Balance at June 30, 2018	$	10,469		$	3,819		$	5,438		$	4,835		$	602		$	89		$	856		$	15

(a) Primarily relates to decommissioning nuclear power facilities, closure of ash impoundments, asbestos removal, closure of landfills at fossil generation facilities, retirement of natural gas mains and removal of renewable energy generation assets.

(b) For the six months ended June 30, 2018, substantially all accretion expense relates to Duke Energy's regulated electric operations and has been deferred in accordance with regulatory accounting treatment.

(c) Primarily relates to ash impoundment closures and nuclear decommissioning of Crystal River Unit 3.

(d) Primarily relates to increases in groundwater monitoring estimates for closure of ash impoundments and a reduction for nuclear decommissioning at Crystal River Unit 3 compared to original estimates.