Debt and Credit Facilities (Summary of Current Maturities of Long-term Debt)(Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 3,951,000,000	$ 3,244,000,000
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 601,000,000
Parent Company [Member] | Unsecured Debt [Member] | Debt Maturing June 2018, 6.250% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	6.25%
Current maturities of long-term debt	$ 250,000,000
Parent Company [Member] | Unsecured Debt [Member] | Debt Maturing June 2018, 2.100% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	2.10%
Current maturities of long-term debt	$ 500,000,000
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 250,000,000	250,000,000
Piedmont Natural Gas [Member] | Unsecured Debt [Member] | Debt Maturing December 2018, Floating Rate [Member]
Debt Instrument [Line Items]
Interest rate	2.821%
Current maturities of long-term debt	$ 250,000,000
Progress Energy [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 1,820,000,000	771,000,000
Progress Energy [Member] | Unsecured Debt [Member] | Debt Maturing March 2019, 7.050% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	7.05%
Current maturities of long-term debt	$ 450,000,000
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	805,000,000	1,205,000,000
Duke Energy Carolinas [Member] | Bonds Maturing April 2018, 5.100% Coupon [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 300,000,000
Duke Energy Carolinas [Member] | First Mortgage Bonds [Member] | Bonds Maturing April 2018, 5.100% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.10%
Current maturities of long-term debt	$ 300,000,000
Duke Energy Carolinas [Member] | First Mortgage Bonds [Member] | Bonds Maturing November 2018, 7.000% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	7.00%
Current maturities of long-term debt	$ 500,000,000
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 768,000,000	768,000,000
Duke Energy Florida [Member] | First Mortgage Bonds [Member] | Bonds Maturing June 2018, 5.650% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.65%
Current maturities of long-term debt	$ 500,000,000
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 603,000,000	$ 3,000,000
Duke Energy Progress [Member] | First Mortgage Bonds [Member] | Bonds Maturing January 2019, 5.300% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.30%
Current maturities of long-term debt	$ 600,000,000