Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 622	$ 717
Net income (attributable to parent)	620	716
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	1,089	991
Equity component of AFUDC	(55)	(62)
Losses (gains) on sales of other assets	100	(11)
Impairment charges	43
Deferred income taxes	199	342
Equity in losses (earnings) of unconsolidated affiliates	24	(29)
Accrued pension and other post-retirement benefit costs	15	6
Contributions to qualified pension plans	(141)
Payments for asset retirement obligations	(122)	(134)
Payment for disposal of other assets	(105)
Other rate case adjustments	37
Provision for rate refunds	158
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	4	(38)
Receivables	64	343
Inventory	101	155
Other current assets	27	(22)
Increase (decrease) in
Accounts payable	(327)	(463)
Taxes accrued	(107)	(28)
Other current liabilities	(171)	(478)
Other assets	(59)	(45)
Other liabilities	(5)	2
Net cash provided by operating activities	1,391	1,246
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(2,087)	(2,160)
Cost of removal, net of salvage	(81)	(39)
Contributions to equity method investments	(74)	(175)
Purchases of debt and equity securities	(958)	(1,386)
Proceeds from sales and maturities of debt and equity securities	930	1,405
Other	6	(6)
Net cash used in investing activities	(2,264)	(2,361)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	1,240	1,563
Proceeds from the issuance of common stock	21
Payments for the redemption of long-term debt	(487)	(408)
Proceeds from issuance of short-term debt with original maturities greater than 90 days	135	25
Payments for the redemption of short-term debt with original maturities greater than 90 days	(50)	(7)
Notes payable and commercial paper	706	1,045
Dividends paid	(599)	(600)
Other	(19)	(22)
Net cash provided by financing activities	947	1,596
Net increase in cash, cash equivalents and restricted cash	74	481
Cash, cash equivalents and restricted cash at beginning of period	505	541
Cash, cash equivalents and restricted cash at end of period	579	1,022
Cash and cash equivalents at beginning of period	358
Cash and cash equivalents at end of period	421
Significant non-cash transactions:
Accrued capital expenditures	799	575
Non-cash dividends	26
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	323	270
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	347	339
Equity component of AFUDC	(21)	(30)
Impairment charges	13
Deferred income taxes	80	162
Accrued pension and other post-retirement benefit costs	1
Contributions to qualified pension plans	(46)
Payments for asset retirement obligations	(55)	(65)
Provision for rate refunds	61
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions		3
Receivables	19	66
Receivable from affiliated companies	(11)	54
Inventory	(9)	4
Other current assets	(144)	(26)
Increase (decrease) in
Accounts payable	(76)	(131)
Accounts payable to affiliated companies	50	3
Taxes accrued	(129)	(53)
Other current liabilities	(23)	(125)
Other assets	12	(3)
Other liabilities	(43)	(2)
Net cash provided by operating activities	349	466
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(621)	(563)
Cost of removal, net of salvage	(17)	(16)
Purchases of debt and equity securities	(494)	(722)
Proceeds from sales and maturities of debt and equity securities	494	722
Notes receivable from affiliated companies		66
Other	(4)	(4)
Net cash used in investing activities	(642)	(517)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	991
Payments for the redemption of long-term debt	(401)	(113)
Notes payable to affiliated companies	(59)	337
Distributions to parent	(250)	(175)
Other	(1)	(1)
Net cash provided by financing activities	280	48
Net increase (decrease) in cash and cash equivalents	(13)	(3)
Cash and cash equivalents at beginning of period	16	14
Cash and cash equivalents at end of period	3	11
Significant non-cash transactions:
Accrued capital expenditures	267	164
Progress Energy [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	237	201
Net income (attributable to parent)	235	199
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	439	365
Equity component of AFUDC	(26)	(24)
Losses (gains) on sales of other assets	(6)	(9)
Impairment charges	29
Deferred income taxes	71	220
Accrued pension and other post-retirement benefit costs	6	(3)
Contributions to qualified pension plans	(45)
Payments for asset retirement obligations	(55)	(60)
Other rate case adjustments	37
Provision for rate refunds	33
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	4	(2)
Receivables	(33)	115
Receivable from affiliated companies	29	100
Inventory	55	65
Other current assets	(60)	(212)
Increase (decrease) in
Accounts payable	(53)	(228)
Accounts payable to affiliated companies	33	(32)
Taxes accrued	8	12
Other current liabilities	(82)	(121)
Other assets	(86)	(58)
Other liabilities	(8)	(14)
Net cash provided by operating activities	527	315
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(762)	(1,011)
Cost of removal, net of salvage	(41)
Purchases of debt and equity securities	(406)	(629)
Proceeds from sales and maturities of debt and equity securities	411	635
Notes receivable from affiliated companies	127	(104)
Other	1	5
Net cash used in investing activities	(670)	(1,104)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		892
Payments for the redemption of long-term debt	(80)	(288)
Notes payable to affiliated companies	177	137
Other	(2)	(4)
Net cash provided by financing activities	95	737
Net increase in cash, cash equivalents and restricted cash	(48)	(52)
Cash, cash equivalents and restricted cash at beginning of period	87	110
Cash, cash equivalents and restricted cash at end of period	39	58
Cash and cash equivalents at beginning of period	40
Cash and cash equivalents at end of period	20
Significant non-cash transactions:
Accrued capital expenditures	316	219
Duke Energy Progress [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	177	147
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	284	228
Equity component of AFUDC	(14)	(13)
Losses (gains) on sales of other assets	(1)	(3)
Impairment charges	32
Deferred income taxes	42	120
Accrued pension and other post-retirement benefit costs	4	(5)
Contributions to qualified pension plans	(25)
Payments for asset retirement obligations	(44)	(47)
Other rate case adjustments	37
Provision for rate refunds	33
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	2	(2)
Receivables	(31)	65
Receivable from affiliated companies	(2)	(1)
Inventory	15	23
Other current assets	(88)	(60)
Increase (decrease) in
Accounts payable	(39)	(192)
Accounts payable to affiliated companies	29	17
Taxes accrued	(28)	(68)
Other current liabilities	(64)	(81)
Other assets	18	(44)
Other liabilities	(5)	(10)
Net cash provided by operating activities	332	74
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(424)	(474)
Cost of removal, net of salvage	(31)	(9)
Purchases of debt and equity securities	(284)	(476)
Proceeds from sales and maturities of debt and equity securities	281	470
Notes receivable from affiliated companies		165
Other	1
Net cash used in investing activities	(457)	(324)
CASH FLOWS FROM FINANCING ACTIVITIES
Payments for the redemption of long-term debt		(250)
Notes payable to affiliated companies	114	502
Other	(1)	(2)
Net cash provided by financing activities	113	250
Net increase (decrease) in cash and cash equivalents	(12)
Cash and cash equivalents at beginning of period	20	11
Cash and cash equivalents at end of period	8	11
Significant non-cash transactions:
Accrued capital expenditures	137	66
Duke Energy Florida [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	103	90
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	152	134
Equity component of AFUDC	(12)	(11)
Impairment charges		1
Deferred income taxes	29	100
Accrued pension and other post-retirement benefit costs	1	1
Contributions to qualified pension plans	(20)
Payments for asset retirement obligations	(11)	(14)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	2
Receivables	(2)	51
Receivable from affiliated companies		(1)
Inventory	39	42
Other current assets	42	(72)
Increase (decrease) in
Accounts payable	(13)	(35)
Accounts payable to affiliated companies	8	(48)
Taxes accrued	38	29
Other current liabilities	(17)	(47)
Other assets	(107)	(13)
Other liabilities	(5)	(5)
Net cash provided by operating activities	227	202
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(338)	(538)
Cost of removal, net of salvage	(10)	9
Purchases of debt and equity securities	(122)	(153)
Proceeds from sales and maturities of debt and equity securities	129	165
Notes receivable from affiliated companies	160	(293)
Other		4
Net cash used in investing activities	(181)	(806)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		892
Payments for the redemption of long-term debt	(80)	(38)
Notes payable to affiliated companies		(297)
Other		(1)
Net cash provided by financing activities	(80)	556
Net increase in cash, cash equivalents and restricted cash	(34)	(48)
Cash, cash equivalents and restricted cash at beginning of period	53	69
Cash, cash equivalents and restricted cash at end of period	19	21
Cash and cash equivalents at beginning of period	13
Cash and cash equivalents at end of period	6
Significant non-cash transactions:
Accrued capital expenditures	179	153
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	(25)	42
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	71	68
Equity component of AFUDC	(4)	(2)
Losses (gains) on sales of other assets	106
Deferred income taxes	(15)	30
Accrued pension and other post-retirement benefit costs	1	1
Payments for asset retirement obligations	(1)	(2)
Provision for rate refunds	16
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions		1
Receivables	(1)	7
Receivable from affiliated companies	56	41
Inventory	25	19
Other current assets	19	9
Increase (decrease) in
Accounts payable	(27)	(10)
Accounts payable to affiliated companies	(95)	1
Taxes accrued	(45)	(52)
Other current liabilities	20	9
Other assets		(6)
Other liabilities	(13)	(3)
Net cash provided by operating activities	88	153
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(188)	(143)
Cost of removal, net of salvage	(14)	(8)
Notes receivable from affiliated companies	14	(85)
Net cash used in investing activities	(188)	(236)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		93
Payments for the redemption of long-term debt		(1)
Notes payable to affiliated companies	101	(8)
Other	(1)	(1)
Net cash provided by financing activities	100	83
Cash and cash equivalents at beginning of period	12	13
Cash and cash equivalents at end of period	12	13
Significant non-cash transactions:
Accrued capital expenditures	64	57
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	100	91
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	131	126
Equity component of AFUDC	(4)	(6)
Deferred income taxes	17	37
Accrued pension and other post-retirement benefit costs	2	1
Contributions to qualified pension plans	(8)
Payments for asset retirement obligations	(11)	(7)
Provision for rate refunds	26
(Increase) decrease in
Receivables		44
Receivable from affiliated companies	26	26
Inventory	(3)	26
Other current assets	(23)	(2)
Increase (decrease) in
Accounts payable	21	(32)
Accounts payable to affiliated companies	(5)	1
Taxes accrued	(1)	41
Other current liabilities	(10)	(15)
Other assets	(1)	(11)
Other liabilities		(3)
Net cash provided by operating activities	257	317
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(231)	(189)
Cost of removal, net of salvage	(7)	(15)
Purchases of debt and equity securities	(6)	(4)
Proceeds from sales and maturities of debt and equity securities	3	2
Notes receivable from affiliated companies		(113)
Other	3	3
Net cash used in investing activities	(238)	(316)
CASH FLOWS FROM FINANCING ACTIVITIES
Payments for the redemption of long-term debt		(2)
Notes payable to affiliated companies	(12)
Other	(1)	(1)
Net cash provided by financing activities	(13)	(3)
Net increase (decrease) in cash and cash equivalents	6	(2)
Cash and cash equivalents at beginning of period	9	17
Cash and cash equivalents at end of period	15	15
Significant non-cash transactions:
Accrued capital expenditures	64	84
Piedmont Natural Gas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	110	95
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	39	37
Deferred income taxes	(7)	50
Equity in losses (earnings) of unconsolidated affiliates	(2)	(3)
Accrued pension and other post-retirement benefit costs	(1)	3
Provision for rate refunds	23
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions		(41)
Receivables	22	40
Inventory	37	37
Other current assets	79	24
Increase (decrease) in
Accounts payable	(15)	(31)
Accounts payable to affiliated companies	19	(5)
Taxes accrued	46	2
Other current liabilities	18	(17)
Other assets	4	25
Other liabilities	(1)	(1)
Net cash provided by operating activities	371	215
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(121)	(141)
Cost of removal, net of salvage	(2)	(1)
Contributions to equity method investments		(12)
Other	2	(2)
Net cash used in investing activities	(121)	(156)
CASH FLOWS FROM FINANCING ACTIVITIES
Notes payable and commercial paper		(330)
Notes payable to affiliated companies	(257)	261
Net cash provided by financing activities	(257)	(69)
Net increase (decrease) in cash and cash equivalents	(7)	(10)
Cash and cash equivalents at beginning of period	19	25
Cash and cash equivalents at end of period	12	15
Significant non-cash transactions:
Accrued capital expenditures	$ 52	$ 24