Employee Retirement Benefits - Net Periodic Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	$ 80	$ 70	$ 66
Interest cost	114	82	83
Expected return on plan assets	(312)	(276)	(270)
Amortization of prior service benefit	(1)	(1)	(1)
Special termination benefits	19	35	38
Postretirement benefits settlement	0	0	0
Net periodic (income) cost	(100)	(90)	(84)
Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	1	1	1
Interest cost	9	7	8
Expected return on plan assets	0	0	0
Amortization of prior service benefit	(15)	(15)	(10)
Special termination benefits	0	0	0
Postretirement benefits settlement	0	0	1
Net periodic (income) cost	(5)	(7)	0
FPL[Member] | Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic (income) cost	(71)	(57)	(51)
FPL[Member] | Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic (income) cost	$ (4)	$ (6)	$ 0