Summarized Financial Information of NEECH - Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net cash provided by operating activities	$ 6,413	$ 6,293	$ 6,089
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures, independent power and other investments and nuclear fuel purchases	(10,740)	(9,636)	(8,377)
Capital contributions from NEE	0	0	0
Cash grants under the Recovery Act	(78)	(335)	(8)
Proceeds from sale of the fiber-optic telecommunications business	1,454	0	0
Sale of independent power and other investments of NEER	178	658	52
Proceeds from sale or maturity of securities in special use funds and other investments	3,207	3,776	4,851
Purchases of securities in special use funds and other investments	(3,244)	(3,829)	(4,982)
Proceeds from sales of noncontrolling interests in NEP	0	645	345
Other - net	149	5	107
Net cash used in investing activities	(8,918)	(8,046)	(7,996)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuances of long-term debt	8,354	5,657	5,772
Retirements of long-term debt	(6,780)	(3,310)	(3,972)
Proceeds from differential membership investors	1,414	1,859	761
Net change in commercial paper	1,419	(106)	(768)
Proceeds from other short-term debt	450	500	1,225
Repayments of other short-term debt	(2)	(662)	(813)
Issuances of common stock - net	55	537	1,298
Proceeds from issuance of NEP convertible preferred units - net	548	0	0
Dividends on common stock	(1,845)	(1,612)	(1,385)
Dividends to NEE	0	0	0
Other - net	(680)	(363)	(221)
Net cash provided by (used in) financing activities	2,933	2,500	1,897
Effects of currency translation on cash, cash equivalents and restricted cash	26	10	17
Net increase in cash, cash equivalents and restricted cash	454	757	7
Cash, cash equivalents and restricted cash at beginning of year	1,529	772	765
Cash, cash equivalents and restricted cash at end of year	1,983	1,529	772
Reportable Legal Entities [Member] | NEE (Guarantor) [Member]
Net cash provided by operating activities	1,968	1,897	1,659
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures, independent power and other investments and nuclear fuel purchases	0	(1)	0
Capital contributions from NEE	(92)	(745)	(1,480)
Cash grants under the Recovery Act	0	0	0
Proceeds from sale of the fiber-optic telecommunications business	0	0	0
Sale of independent power and other investments of NEER	0	0	0
Proceeds from sale or maturity of securities in special use funds and other investments	9	0	0
Purchases of securities in special use funds and other investments	0	0	0
Proceeds from sales of noncontrolling interests in NEP	0	0	0
Other - net	7	0	0
Net cash used in investing activities	(76)	(746)	(1,480)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuances of long-term debt	0	0	0
Retirements of long-term debt	0	0	0
Proceeds from differential membership investors	0	0	0
Net change in commercial paper	0	0	0
Proceeds from other short-term debt	0	0	0
Repayments of other short-term debt	0	0	0
Issuances of common stock - net	55	537	1,298
Proceeds from issuance of NEP convertible preferred units - net	0	0	0
Dividends on common stock	(1,845)	(1,612)	(1,385)
Dividends to NEE	0	0	0
Other - net	(102)	(75)	(92)
Net cash provided by (used in) financing activities	(1,892)	(1,150)	(179)
Effects of currency translation on cash, cash equivalents and restricted cash	0	0	0
Net increase in cash, cash equivalents and restricted cash	0	1	0
Cash, cash equivalents and restricted cash at beginning of year	1	0	0
Cash, cash equivalents and restricted cash at end of year	1	1	0
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Net cash provided by operating activities	2,711	2,129	2,462
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures, independent power and other investments and nuclear fuel purchases	(5,449)	(5,701)	(4,744)
Capital contributions from NEE	0	0	0
Cash grants under the Recovery Act	(78)	(335)	(8)
Proceeds from sale of the fiber-optic telecommunications business	1,454	0	0
Sale of independent power and other investments of NEER	178	658	52
Proceeds from sale or maturity of securities in special use funds and other investments	1,221	1,281	1,120
Purchases of securities in special use funds and other investments	(1,163)	(1,323)	(1,190)
Proceeds from sales of noncontrolling interests in NEP	0	645	345
Other - net	124	(19)	79
Net cash used in investing activities	(3,557)	(4,124)	(4,330)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuances of long-term debt	6,393	5,349	4,689
Retirements of long-term debt	(5,907)	(3,048)	(3,421)
Proceeds from differential membership investors	1,414	1,859	761
Net change in commercial paper	0	(318)	318
Proceeds from other short-term debt	0	0	1,125
Repayments of other short-term debt	0	(212)	(813)
Issuances of common stock - net	0	0	0
Proceeds from issuance of NEP convertible preferred units - net	548	0	0
Dividends on common stock	0	0	0
Dividends to NEE	(633)	(650)	(698)
Other - net	(563)	(292)	(150)
Net cash provided by (used in) financing activities	1,252	2,688	1,811
Effects of currency translation on cash, cash equivalents and restricted cash	26	10	17
Net increase in cash, cash equivalents and restricted cash	432	703	(40)
Cash, cash equivalents and restricted cash at beginning of year	1,375	672	712
Cash, cash equivalents and restricted cash at end of year	1,807	1,375	672
Consolidation, Eliminations [Member]
Net cash provided by operating activities	1,734	2,267	1,968
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures, independent power and other investments and nuclear fuel purchases	(5,291)	(3,934)	(3,633)
Capital contributions from NEE	92	745	1,480
Cash grants under the Recovery Act	0	0	0
Proceeds from sale of the fiber-optic telecommunications business	0	0	0
Sale of independent power and other investments of NEER	0	0	0
Proceeds from sale or maturity of securities in special use funds and other investments	1,977	2,495	3,731
Purchases of securities in special use funds and other investments	(2,081)	(2,506)	(3,792)
Proceeds from sales of noncontrolling interests in NEP	0	0	0
Other - net	18	24	28
Net cash used in investing activities	(5,285)	(3,176)	(2,186)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuances of long-term debt	1,961	308	1,083
Retirements of long-term debt	(873)	(262)	(551)
Proceeds from differential membership investors	0	0	0
Net change in commercial paper	1,419	212	(1,086)
Proceeds from other short-term debt	450	500	100
Repayments of other short-term debt	(2)	(450)	0
Issuances of common stock - net	0	0	0
Proceeds from issuance of NEP convertible preferred units - net	0	0	0
Dividends on common stock	0	0	0
Dividends to NEE	633	650	698
Other - net	(15)	4	21
Net cash provided by (used in) financing activities	3,573	962	265
Effects of currency translation on cash, cash equivalents and restricted cash	0	0	0
Net increase in cash, cash equivalents and restricted cash	22	53	47
Cash, cash equivalents and restricted cash at beginning of year	153	100	53
Cash, cash equivalents and restricted cash at end of year	$ 175	$ 153	$ 100