Employee Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	$ 22	$ 21
Interest cost	16	23
Expected return on plan assets	(85)	(80)
Amortization of prior service benefit	0	0
Amortization of actuarial loss	6	4
Special termination benefits	0	2
Net periodic benefit (income) cost	(41)	(30)
Postretirement Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	1	0
Interest cost	1	2
Expected return on plan assets	0	0
Amortization of prior service benefit	(4)	(4)
Amortization of actuarial loss	1	1
Special termination benefits	0	0
Net periodic benefit (income) cost	(1)	(1)
FPL [Member] | Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	(27)	(21)
FPL [Member] | Postretirement Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	$ (1)	$ (1)