Debt and Credit Facilities (Summary of Current Maturities of Long-term Debt)(Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 3,201	$ 2,074
Unsecured Debt [Member] | 15.681% Unsecured Debt Maturing May 2017 [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 56
Interest rate	15.681%
Secured Debt [Member] | 2.155% Secured Debt Maturing June 2017 [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 45
Interest rate	2.155%
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 573
Parent Company [Member] | Unsecured Debt [Member] | 2.150% Unsecured Debt Maturing November 2016 [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 500
Interest rate	2.15%
Parent Company [Member] | Unsecured Debt [Member] | 1.034% Unsecured Debt Maturing April 2017 [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 400
Interest rate	1.034%
Parent Company [Member] | Unsecured Debt [Member] | 1.625% Unsecured Debt Maturing August 2017 [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 700
Interest rate	1.625%
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 468	356
Duke Energy Carolinas [Member] | First Mortgage Bonds [Member] | 1.750% First Mortgage Bonds Maturing December 2016 [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 350
Interest rate	1.75%
Duke Energy Carolinas [Member] | Tax Exempt Bonds [Member] | 3.600% Tax-exempt Bonds Maturing February 2017[Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 77
Interest rate	3.60%
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 252	2
Duke Energy Progress [Member] | First Mortgage Bonds [Member] | 1.035% First Mortgage Bonds Maturing March 2017 [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 250
Interest rate	1.035%
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 326	13
Duke Energy Florida [Member] | First Mortgage Bonds [Member] | 5.800% First Mortgage Bonds Maturing September 2017 [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 250
Interest rate	5.80%
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 54	106
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 71	$ 547