Debt and Credit Facilities (Summary of Current Maturities of Long-term Debt)(Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 3,472	$ 2,319
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 337
Parent Company [Member] | Unsecured Debt [Member] | Unsecured Debt Maturing August 2017, 1.625% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	1.625%
Current maturities of long-term debt	$ 700
Parent Company [Member] | Unsecured Debt [Member] | Unsecured Debt Maturing June 2018, 6.250% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	6.25%
Current maturities of long-term debt	$ 250
Parent Company [Member] | Unsecured Debt [Member] | Unsecured Debt Maturing June 2018, 2.100% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	2.10%
Current maturities of long-term debt	$ 500
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 704	116
Duke Energy Carolinas [Member] | First Mortgage Bonds [Member] | First Mortgage Bonds Maturing January 2018, 5.250% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.25%
Current maturities of long-term debt	$ 400
Duke Energy Carolinas [Member] | First Mortgage Bonds [Member] | First Mortgage Bonds Maturing April 2018, 5.100% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.10%
Current maturities of long-term debt	$ 300
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 203	452
Duke Energy Progress [Member] | First Mortgage Bonds [Member] | First Mortgage Bonds Maturing November 2017, 1.252% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	1.372%
Current maturities of long-term debt	$ 200
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 819	326
Duke Energy Florida [Member] | First Mortgage Bonds [Member] | First Mortgage Bonds Maturing September 2017, 5.800% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.80%
Current maturities of long-term debt	$ 250
Duke Energy Florida [Member] | First Mortgage Bonds [Member] | First Mortgage Bonds Maturing June 2018, 5.650% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.65%
Current maturities of long-term debt	$ 500
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	1	1
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	3	3
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 35	$ 35
Piedmont Natural Gas [Member] | Unsecured Debt [Member] | Unsecured Debt Maturing September 2017, 8.510% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	8.51%
Current maturities of long-term debt	$ 35