Employee Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	$ 18	$ 16	$ 52	$ 49
Interest cost	20	21	62	63
Expected return on plan assets	(69)	(67)	(207)	(202)
Amortization of prior service benefit	0	0	(1)	(1)
Special termination benefits	14	0	14	38
Postretirement benefits settlement	0	0	0	0
Net periodic benefit (income) cost	(17)	(30)	(80)	(53)
Postretirement Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	0	0	1	1
Interest cost	2	2	5	6
Expected return on plan assets	0	0	0	0
Amortization of prior service benefit	(4)	(4)	(12)	(6)
Special termination benefits	0	0	0	0
Postretirement benefits settlement	0	0	0	1
Net periodic benefit (income) cost	(2)	(2)	(6)	2
FPL [Member] | Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	(11)	(20)	(51)	(32)
FPL [Member] | Postretirement Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	$ (2)	$ (2)	$ (4)	$ 1