Debt and Credit Facilities (Summary of Debt Issuances) (Details) - USD ($)	1 Months Ended	9 Months Ended
	Apr. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Debt issuances		$ 4,050,000,000
Repayments of long-term debt		2,278,000,000	$ 2,035,000,000
Parent Company [Member]
Debt Instrument [Line Items]
Debt issuances		1,250,000,000
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Debt issuances		1,000,000,000
Repayments of long-term debt		704,000,000	115,000,000
Duke Energy Carolinas [Member] | First Mortgage Bonds Maturing April 2018, 5.100% Coupon
Debt Instrument [Line Items]
Repayments of long-term debt	$ 300,000,000
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Debt issuances		800,000,000
Repayments of long-term debt		2,000,000	270,000,000
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Debt issuances		1,000,000,000
Repayments of long-term debt		717,000,000	$ 341,000,000
Unsecured Debt [Member] | March 2018 Debt Issuance 3.950% Coupon Due 2025 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 250,000,000
Interest rate		3.95%
Unsecured Debt [Member] | May 2018 Debt Issuance 2.819% Coupon Due 2021 [Member] [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
Interest rate		2.819%
Unsecured Debt [Member] | September 2018 Debt Issuance 5.625% Coupon Due 2078 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
Interest rate		5.625%
Unsecured Debt [Member] | Parent Company [Member] | March 2018 Debt Issuance 3.950% Coupon Due 2025 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 250,000,000
Unsecured Debt [Member] | Parent Company [Member] | May 2018 Debt Issuance 2.819% Coupon Due 2021 [Member] [Member]
Debt Instrument [Line Items]
Debt issuances		500,000,000
Unsecured Debt [Member] | Parent Company [Member] | September 2018 Debt Issuance 5.625% Coupon Due 2078 [Member]
Debt Instrument [Line Items]
Debt issuances		500,000,000
First Mortgage [Member] | March 2018 Debt Issuance 3.050% Coupon Due 2023 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
Interest rate		3.05%
First Mortgage [Member] | March 2018 Debt Issuance 3.950% Coupon Due 2048 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
Interest rate		3.95%
First Mortgage [Member] | June 2018 Debt issuance 3.80% coupon Due 2028 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 600,000,000
Interest rate		3.80%
First Mortgage [Member] | June 2018 Debt Issuance 4.20 Coupon Due 2048 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 400,000,000
Interest rate		4.20%
First Mortgage [Member] | August 2018 Debt Issuance 3.375% Coupon Due 2023 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 300,000,000
Interest rate		3.375%
First Mortgage [Member] | August 2018 Debt Issuance 3.700% Coupon Due 2028 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
Interest rate		3.70%
First Mortgage [Member] | Duke Energy Carolinas [Member] | March 2018 Debt Issuance 3.050% Coupon Due 2023 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
First Mortgage [Member] | Duke Energy Carolinas [Member] | March 2018 Debt Issuance 3.950% Coupon Due 2048 [Member]
Debt Instrument [Line Items]
Debt issuances		500,000,000
First Mortgage [Member] | Duke Energy Progress [Member] | August 2018 Debt Issuance 3.375% Coupon Due 2023 [Member]
Debt Instrument [Line Items]
Debt issuances		300,000,000
First Mortgage [Member] | Duke Energy Progress [Member] | August 2018 Debt Issuance 3.700% Coupon Due 2028 [Member]
Debt Instrument [Line Items]
Debt issuances		500,000,000
First Mortgage [Member] | Duke Energy Florida [Member] | June 2018 Debt issuance 3.80% coupon Due 2028 [Member]
Debt Instrument [Line Items]
Debt issuances		600,000,000
First Mortgage [Member] | Duke Energy Florida [Member] | June 2018 Debt Issuance 4.20 Coupon Due 2048 [Member]
Debt Instrument [Line Items]
Debt issuances		$ 400,000,000