Equity (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Dec. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications		$ (2)		$ (43)
Amounts reclassified from AOCI		0		4
Total other comprehensive loss, net of tax	$ (2)	(2)	$ (39)	(39)
Impact of disposal of a business			10
Attributable to noncontrolling interests	2		(6)
Attributable to NEE	(98)		(192)		$ (92)
Net Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	8		(27)
Other comprehensive income (loss) before reclassifications		0		0
Amounts reclassified from AOCI		2		2
Total other comprehensive loss, net of tax		2		2
Impact of disposal of a business			23
Attributable to noncontrolling interests	0		0
Attributable to NEE	10		(2)
Ending balance		10		(2)
Net Unrealized Gains (Losses) on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	20		11
Other comprehensive income (loss) before reclassifications		(8)		(8)
Amounts reclassified from AOCI		(3)		(1)
Total other comprehensive loss, net of tax		(11)		(9)
Impact of disposal of a business			0
Attributable to noncontrolling interests	0		0
Attributable to NEE	9		2
Ending balance		9		2
Defined Benefit Pension and Other Benefits Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(75)		(114)
Other comprehensive income (loss) before reclassifications		0		0
Amounts reclassified from AOCI		1		3
Total other comprehensive loss, net of tax		1		3
Impact of disposal of a business			0
Attributable to noncontrolling interests	0		0
Attributable to NEE	(74)		(111)
Ending balance		(74)		(111)
Net Unrealized Gains (Losses) on Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(49)		(42)
Other comprehensive income (loss) before reclassifications		6		(35)
Amounts reclassified from AOCI		0		0
Total other comprehensive loss, net of tax		6		(35)
Impact of disposal of a business			(13)
Attributable to noncontrolling interests	2		(6)
Attributable to NEE	(47)		(84)
Ending balance		(45)		(90)
Other Comprehensive Income (Loss) Related to Equity Method Investees
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	4		3
Other comprehensive income (loss) before reclassifications		0		0
Amounts reclassified from AOCI		0		0
Total other comprehensive loss, net of tax		0		0
Impact of disposal of a business			0
Attributable to noncontrolling interests	0		0
Attributable to NEE	4		3
Ending balance		4		3
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(92)		(169)
Total other comprehensive loss, net of tax	$ (5)		$ (33)
Ending balance		$ (96)		$ (198)