Income Taxes (Deferred Income Taxes) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	$ 125	$ 164
Capital lease obligations	462	60
Pension, postretirement and other employee benefits	303	347
Progress Energy merger purchase accounting adjustments	389	483
Tax credits and NOL carryforwards	3,925	4,580
Other	97	25
Valuation allowance	(587)	(484)
Total deferred income tax assets	4,714	5,175
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(1,664)	(1,317)
Accelerated depreciation rates	(10,813)	(10,124)
Regulatory assets and deferred debits, net	(1,115)	(1,540)
Total deferred income tax liabilities	(13,592)	(12,981)
Net deferred income tax liabilities	(8,878)	(7,806)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	3,925	4,580
Valuation allowance	(587)	(484)
General Business Credits
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards	1,821
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	1,821
AMT credits
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards	286
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	286
NOL Carryforwards | Federal
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards	169
Valuation allowance	(4)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	169
Valuation allowance	(4)
NOL Carryforwards | State
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards	303
Valuation allowance	(97)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	303
Valuation allowance	(97)
NOL Carryforwards | Foreign
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards	12
Valuation allowance	(12)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	12
Valuation allowance	(12)
Capital loss carryforwards | Federal
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards	87
Valuation allowance	(87)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	87
Valuation allowance	(87)
Foreign Tax Credit
Deferred Tax Assets, Gross [Abstract]
Valuation allowance	(387)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Valuation allowance	(387)
Foreign Tax Credit | Foreign
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards	1,237
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	1,237
Charitable contribution carryforwards
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards	10
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	10
Duke Energy Carolinas
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	24	64
Capital lease obligations	72	26
Pension, postretirement and other employee benefits	(5)	24
Tax credits and NOL carryforwards	262	257
Other	5	6
Total deferred income tax assets	358	377
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(981)	(795)
Accelerated depreciation rates	(3,254)	(3,207)
Regulatory assets and deferred debits, net	(44)	(64)
Total deferred income tax liabilities	(4,279)	(4,066)
Net deferred income tax liabilities	(3,921)	(3,689)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	262	257
Progress Energy
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	25	35
Capital lease obligations	193
Pension, postretirement and other employee benefits	88	110
Tax credits and NOL carryforwards	486	693
Other	8	5
Total deferred income tax assets	800	843
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(577)	(430)
Accelerated depreciation rates	(3,798)	(3,369)
Regulatory assets and deferred debits, net	(887)	(985)
Total deferred income tax liabilities	(5,262)	(4,784)
Net deferred income tax liabilities	(4,462)	(3,941)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	486	693
Duke Energy Progress
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	49	53
Capital lease obligations	92
Pension, postretirement and other employee benefits	38	47
Tax credits and NOL carryforwards	176	215
Other	3	5
Total deferred income tax assets	358	320
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(390)	(272)
Accelerated depreciation rates	(1,918)	(1,735)
Regulatory assets and deferred debits, net	(438)	(432)
Total deferred income tax liabilities	(2,746)	(2,439)
Net deferred income tax liabilities	(2,388)	(2,119)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	176	215
Duke Energy Florida
Deferred Tax Assets, Gross [Abstract]
Capital lease obligations	102
Pension, postretirement and other employee benefits	44	58
Tax credits and NOL carryforwards	253	363
Other	2
Total deferred income tax assets	401	421
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(190)	(163)
Accelerated depreciation rates	(1,913)	(1,670)
Regulatory assets and deferred debits, net	(477)	(574)
Total deferred income tax liabilities	(2,580)	(2,407)
Net deferred income tax liabilities	(2,179)	(1,986)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	253	363
Duke Energy Ohio
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	14	17
Capital lease obligations	5
Pension, postretirement and other employee benefits	17	16
Tax credits and NOL carryforwards	16	42
Regulatory liabilities and deferred credits	36	56
Investments and other assets	10	18
Other	8	1
Total deferred income tax assets	106	150
Deferred Tax Liabilities, Gross [Abstract]
Accelerated depreciation rates	(1,028)	(967)
Total deferred income tax liabilities	(1,028)	(967)
Net deferred income tax liabilities	(922)	(817)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	16	42
Duke Energy Indiana
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	5	6
Capital lease obligations	17	2
Pension, postretirement and other employee benefits	27	24
Tax credits and NOL carryforwards	176	237
Regulatory liabilities and deferred credits	52
Other	1	(1)
Total deferred income tax assets	278	268
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets	(12)	(5)
Accelerated depreciation rates	(1,416)	(1,081)
Regulatory assets and deferred debits, net		(191)
Total deferred income tax liabilities	(1,428)	(1,277)
Net deferred income tax liabilities	(1,150)	(1,009)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	176	237
Piedmont
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities	22	17
Capital lease obligations	6
Pension, postretirement and other employee benefits	(3)	(1)
Tax credits and NOL carryforwards	19	110
Regulatory liabilities and deferred credits	42	48
Investments and other assets	2	16
Other	6
Total deferred income tax assets	94	190
Deferred Tax Liabilities, Gross [Abstract]
Accelerated depreciation rates	(802)	(733)
Other		(8)
Total deferred income tax liabilities	(802)	(741)
Net deferred income tax liabilities	(708)	(551)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards	$ 19	$ 110