Debt and Credit Facilities (Summary of Debt Issuances) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Debt issuances	$ 5,120,000,000
Repayments of Debt	2,035,000,000	$ 988,000,000
Current maturities of long-term debt	2,485,000,000		$ 2,319,000,000
Parent Company [Member]
Debt Instrument [Line Items]
Debt issuances	2,500,000,000
Parent Company [Member] | August 2017 Debt Maturity [Member]
Debt Instrument [Line Items]
Repayments of Debt	700,000,000
Parent Company [Member] | April 2017 Maturity [Member]
Debt Instrument [Line Items]
Repayments of Debt	400,000,000
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Debt issuances	800,000,000
Repayments of Debt	270,000,000	15,000,000
Current maturities of long-term debt	203,000,000		452,000,000
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Debt issuances	900,000,000
Repayments of Debt	341,000,000	12,000,000
Current maturities of long-term debt	567,000,000		326,000,000
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Debt issuances	100,000,000
Repayments of Debt	2,000,000	$ 53,000,000
Current maturities of long-term debt			$ 1,000,000
Unsecured Debt [Member] | April 2017 Debt Issuance, 3.364% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 420,000,000
Interest rate	3.364%
Unsecured Debt [Member] | June 2017 Debt Issuance, 2.100% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 330,000,000
Interest rate	2.10%
Unsecured Debt [Member] | August 2017 Debt Issuance, 2.400% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
Interest rate	2.40%
Unsecured Debt [Member] | August 2017 Debt Issuance, 3.150% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 750,000,000
Interest rate	3.15%
Unsecured Debt [Member] | August 2017 Debt Issuance, 3.950% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
Interest rate	3.95%
Unsecured Debt [Member] | Parent Company [Member] | April 2017 Debt Issuance, 3.364% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 420,000,000
Unsecured Debt [Member] | Parent Company [Member] | June 2017 Debt Issuance, 2.100% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	330,000,000
Unsecured Debt [Member] | Parent Company [Member] | August 2017 Debt Issuance, 2.400% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	500,000,000
Unsecured Debt [Member] | Parent Company [Member] | August 2017 Debt Issuance, 3.150% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	750,000,000
Unsecured Debt [Member] | Parent Company [Member] | August 2017 Debt Issuance, 3.950% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	500,000,000
Secured Debt [Member] | February 2017 Debt Issuance, 4.120% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 587,000,000
Interest rate	4.12%
Secured Debt [Member] | August 2017 Debt Issuance, 4.110% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 233,000,000
Interest rate	4.11%
First Mortgage [Member] | January 2017 Debt Issuance, 1.850% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 250,000,000
Interest rate	1.85%
First Mortgage [Member] | January 2017 Debt Issuance, 3.200% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 650,000,000
Interest rate	3.20%
First Mortgage [Member] | March 2017 Debt Issuance, 3.700% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 100,000,000
Interest rate	3.70%
First Mortgage [Member] | September 2017 Debt Issuance, Floating Rate [Member]
Debt Instrument [Line Items]
Debt issuances	$ 300,000,000
Interest rate	1.50%
First Mortgage [Member] | September 2017 Debt Issuance, 3.600% Coupon
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
Interest rate	3.60%
First Mortgage [Member] | Duke Energy Progress [Member] | September 2017 Debt Issuance, Floating Rate [Member]
Debt Instrument [Line Items]
Debt issuances	$ 300,000,000
First Mortgage [Member] | Duke Energy Progress [Member] | September 2017 Debt Issuance, 3.600% Coupon
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
First Mortgage [Member] | Duke Energy Progress [Member] | Bonds Maturing November 2017, Floating Rate [Member]
Debt Instrument [Line Items]
Interest rate	1.516%
Current maturities of long-term debt	$ 200,000,000
First Mortgage [Member] | Duke Energy Florida [Member] | January 2017 Debt Issuance, 1.850% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	250,000,000
First Mortgage [Member] | Duke Energy Florida [Member] | January 2017 Debt Issuance, 3.200% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	650,000,000
First Mortgage [Member] | Duke Energy Florida [Member] | Bonds Maturing September 2017, 5.800% Coupon [Member]
Debt Instrument [Line Items]
Repayments of Debt	250,000,000
First Mortgage [Member] | Duke Energy Ohio [Member] | March 2017 Debt Issuance, 3.700% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 100,000,000