Commitments and Contingencies (Table)

3 Months Ended

Mar. 31, 2017

Valuation and Qualifying Accounts Disclosure [Line Items]

Schedule of Additional Possible Losses in Excess of Recorded Environmental Reserves

Additional losses in excess of recorded reserves that could be incurred for the stages of investigation, remediation and monitoring for environmental sites that have been evaluated at this time are not material except as presented in the table below.

(in millions)
Duke Energy	$	71
Duke Energy Carolinas	22
Duke Energy Ohio	36
Duke Energy Indiana	7
Piedmont	2

Reserve for Environmental Costs [Member]

Valuation and Qualifying Accounts Disclosure [Line Items]

Schedule of Legal Reserves

The following tables contain information regarding reserves for probable and estimable costs related to the various environmental sites. These reserves are recorded in Other within Other Noncurrent Liabilities on the Condensed Consolidated Balance Sheets.

	Three Months Ended March 31, 2017
				Duke					Duke		Duke			Duke			Duke
	Duke			Energy		Progress			Energy		Energy			Energy			Energy
(in millions)	Energy			Carolinas		Energy			Progress		Florida			Ohio			Indiana			Piedmont
Balance at beginning of period	$	98		$	10	$	18		$	3	$	14		$	59		$	10		$	1
Provisions/adjustments	6			1		—			—		1			4			(1		)	1
Cash reductions	(6		)	—		(1		)	—		(1		)	(4		)	—			—
Balance at end of period	$	98		$	11	$	17		$	3	$	14		$	59		$	9		$	2

	Three Months Ended March 31, 2016
				Duke						Duke			Duke			Duke		Duke
	Duke			Energy			Progress			Energy			Energy			Energy		Energy
(in millions)	Energy			Carolinas			Energy			Progress			Florida			Ohio		Indiana		Piedmont
Balance at beginning of period	$	94		$	10		$	17		$	3		$	14		$	54	$	12	$	1
Provisions/adjustments	10			2			1			—			1			—		6		—
Cash reductions	(3		)	(1		)	(2		)	(1		)	(1		)	—		—		—
Balance at end of period	$	101		$	11		$	16		$	2		$	14		$	54	$	18	$	1

Legal Reserve [Member]

Valuation and Qualifying Accounts Disclosure [Line Items]

Schedule of Legal Reserves

The table below presents recorded reserves based on management’s best estimate of probable loss for legal matters, excluding asbestos-related reserves and the exit obligation discussed above related to the termination of an EPC contract. Reserves are classified on the Condensed Consolidated Balance Sheets in Other within Other Noncurrent Liabilities and Accounts payable and Other within Current Liabilities. The reasonably possible range of loss in excess of recorded reserves is not material, other than as described above.

(in millions)	March 31, 2017		December 31, 2016
Reserves for Legal Matters
Duke Energy	$	91	$	98
Duke Energy Carolinas	23		23
Progress Energy	57		59
Duke Energy Progress	13		14
Duke Energy Florida	27		28
Duke Energy Ohio	4		4
Piedmont	2		2