Condensed Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Revenues
Regulated electric	$ 5,284	$ 4,913
Regulated natural gas	700	646
Nonregulated electric and other	151	170
Total operating revenues	6,135	5,729
Operating Expenses
Fuel used in electric generation and purchased power	1,676	1,449
Cost of natural gas	313	258
Operation, maintenance and other	1,464	1,468
Depreciation and amortization	967	859
Property and other taxes	316	304
Impairment charges	43
Total operating expenses	4,779	4,338
(Loss) Gains on Sales of Other Assets and Other, net	(100)	11
Operating Income	1,256	1,402
Other Income and Expenses
Equity in (losses) earnings of unconsolidated affiliates	(24)	29
Other income and expenses, net	86	121
Total other income and expenses	62	150
Interest Expense	515	491
Income Before Income Taxes	803	1,061
Income Tax Expense	181	344
Net income	622	717
Less: Net Income Attributable to Noncontrolling Interests	2	1
Net Income Attributable to Parent	620	716
Other Comprehensive Income (Loss), net of tax
Pension and OPEB adjustments	1	1
Net unrealized gain on cash flow hedges	12	2
Reclassification into earnings from cash flow hedges	1	1
Unrealized gains on available-for-sale securities	(3)	4
Other Comprehensive Income, net of tax	11	8
Comprehensive Income	633	725
Less: Comprehensive Income Attributable to Noncontrolling Interests	2	1
Comprehensive Income Attributable to Parent	$ 631	$ 724
Net income attributable to Duke Energy Corporation common stockholders
Basic (usd per share)	$ 0.88	$ 1.02
Diluted (usd per share)	$ 0.88	$ 1.02
Weighted average shares outstanding
Basic (shares)	701	700
Diluted (shares)	701	700
Duke Energy Carolinas [Member]
Operating Revenues
Total operating revenues	$ 1,763	$ 1,716
Operating Expenses
Fuel used in electric generation and purchased power	473	428
Operation, maintenance and other	451	495
Depreciation and amortization	272	254
Property and other taxes	72	68
Impairment charges	13
Total operating expenses	1,281	1,245
Operating Income	482	471
Other Income and Expenses
Total other income and expenses	39	50
Interest Expense	107	103
Income Before Income Taxes	414	418
Income Tax Expense	91	148
Net Income Attributable to Parent	323	270
Other Comprehensive Income (Loss), net of tax
Reclassification into earnings from cash flow hedges	1
Other Comprehensive Income, net of tax	1
Comprehensive Income Attributable to Parent	324	270
Progress Energy [Member]
Operating Revenues
Total operating revenues	2,576	2,179
Operating Expenses
Fuel used in electric generation and purchased power	976	726
Operation, maintenance and other	623	560
Depreciation and amortization	384	313
Property and other taxes	123	117
Impairment charges	29
Total operating expenses	2,135	1,716
(Loss) Gains on Sales of Other Assets and Other, net	6	8
Operating Income	447	471
Other Income and Expenses
Total other income and expenses	35	40
Interest Expense	209	206
Income Before Income Taxes	273	305
Income Tax Expense	36	104
Net income	237	201
Less: Net Income Attributable to Noncontrolling Interests	2	2
Net Income Attributable to Parent	235	199
Other Comprehensive Income (Loss), net of tax
Pension and OPEB adjustments		1
Net unrealized gain on cash flow hedges	2
Reclassification into earnings from cash flow hedges		1
Unrealized gains on available-for-sale securities		1
Other Comprehensive Income, net of tax	2	3
Comprehensive Income	239	204
Less: Comprehensive Income Attributable to Noncontrolling Interests	2	2
Comprehensive Income Attributable to Parent	237	202
Duke Energy Progress [Member]
Operating Revenues
Total operating revenues	1,460	1,219
Operating Expenses
Fuel used in electric generation and purchased power	509	364
Operation, maintenance and other	381	362
Depreciation and amortization	235	181
Property and other taxes	35	40
Impairment charges	32
Total operating expenses	1,192	947
(Loss) Gains on Sales of Other Assets and Other, net	1	2
Operating Income	269	274
Other Income and Expenses
Total other income and expenses	18	31
Interest Expense	81	82
Income Before Income Taxes	206	223
Income Tax Expense	29	76
Net Income Attributable to Parent	177	147
Other Comprehensive Income (Loss), net of tax
Comprehensive Income Attributable to Parent	177	147
Duke Energy Florida [Member]
Operating Revenues
Total operating revenues	1,115	959
Operating Expenses
Fuel used in electric generation and purchased power	467	362
Operation, maintenance and other	237	195
Depreciation and amortization	150	132
Property and other taxes	88	77
Impairment charges		1
Total operating expenses	942	767
Operating Income	173	192
Other Income and Expenses
Total other income and expenses	21	20
Interest Expense	71	70
Income Before Income Taxes	123	142
Income Tax Expense	20	52
Net Income Attributable to Parent	103	90
Other Comprehensive Income (Loss), net of tax
Unrealized gains on available-for-sale securities		1
Other Comprehensive Income, net of tax		1
Comprehensive Income Attributable to Parent	103	91
Duke Energy Ohio [Member]
Operating Revenues
Regulated electric	336	337
Regulated natural gas	174	170
Nonregulated electric and other	14	11
Total operating revenues	524	518
Operating Expenses
Fuel used in electric generation and purchased power	92	97
Fuel used in electric generation and purchased power – nonregulated	15	15
Cost of natural gas	54	54
Operation, maintenance and other	131	131
Depreciation and amortization	70	67
Property and other taxes	77	72
Total operating expenses	439	436
(Loss) Gains on Sales of Other Assets and Other, net	(106)
Operating Income	(21)	82
Other Income and Expenses
Total other income and expenses	6	5
Interest Expense	22	22
Income Before Income Taxes	(37)	65
Income Tax Expense	(12)	23
Net Income Attributable to Parent	(25)	42
Other Comprehensive Income (Loss), net of tax
Comprehensive Income Attributable to Parent	(25)	42
Duke Energy Indiana [Member]
Operating Revenues
Total operating revenues	731	758
Operating Expenses
Fuel used in electric generation and purchased power	232	251
Operation, maintenance and other	181	176
Depreciation and amortization	130	125
Property and other taxes	20	22
Total operating expenses	563	574
Operating Income	168	184
Other Income and Expenses
Total other income and expenses	7	10
Interest Expense	40	44
Income Before Income Taxes	135	150
Income Tax Expense	35	59
Net Income Attributable to Parent	100	91
Other Comprehensive Income (Loss), net of tax
Comprehensive Income Attributable to Parent	100	91
Piedmont Natural Gas [Member]
Operating Revenues
Total operating revenues	553	500
Operating Expenses
Cost of natural gas	259	205
Operation, maintenance and other	82	77
Depreciation and amortization	39	35
Property and other taxes	12	13
Total operating expenses	392	330
Operating Income	161	170
Other Income and Expenses
Equity in (losses) earnings of unconsolidated affiliates	2	3
Other income and expenses, net	3
Total other income and expenses	5	3
Interest Expense	21	20
Income Before Income Taxes	145	153
Income Tax Expense	35	58
Net Income Attributable to Parent	110	95
Other Comprehensive Income (Loss), net of tax
Comprehensive Income Attributable to Parent	$ 110	$ 95