Variable Interest Entities (Receivables Sold)(Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - Cinergy Receivables [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Receivables sold	$ 267	$ 233
Less: retained interests	82	47
Net receivables sold	185	186
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Receivables sold	306	260
Less: retained interests	101	60
Net receivables sold	$ 205	$ 200