Debt and Credit Facilities (Summary of Current Maturities of Long-term Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 2,501	$ 3,406
Other debt obligations [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 501
Parent Company [Member] | Unsecured Debt [Member] | Debt Maturing September 2019, 5.050% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.05%
Current maturities of long-term debt	$ 500
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 350	350
Piedmont Natural Gas [Member] | Unsecured Debt [Member] | Debt Maturing September 2019, 3.181% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	3.181%
Current maturities of long-term debt	$ 350
Duke Energy Kentucky [Member] | Secured Debt [Member] | Debt Maturing October 2019, 4.650% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	4.65%
Current maturities of long-term debt	$ 100
Progress Energy [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 825	1,672
Progress Energy [Member] | Secured Debt [Member] | Debt Maturing December 2019, 4.875% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	4.875%
Current maturities of long-term debt	$ 350
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 551	551
Duke Energy Ohio [Member] | First Mortgage Bonds [Member] | Bonds Maturing April 2019, 5.450% Coupon [Member] [Member]
Debt Instrument [Line Items]
Interest rate	5.45%
Current maturities of long-term debt	$ 450
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 470	$ 270
Duke Energy Florida [Member] | First Mortgage Bonds [Member] | Bonds Maturing January 2020, 1.850% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	1.85%
Current maturities of long-term debt	$ 250