Employee Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	$ 18	$ 17	$ 35	$ 33
Interest cost	20	21	41	42
Expected return on plan assets	(69)	(68)	(138)	(135)
Amortization of prior service benefit	0	(1)	0	(1)
Special termination benefits	0	37	0	38
Postretirement benefits settlement	0	0	0	0
Net periodic benefit (income) cost	(31)	6	(62)	(23)
Postretirement Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	0	1	1	1
Interest cost	2	2	3	4
Expected return on plan assets	0	0	0	0
Amortization of prior service benefit	(4)	(2)	(8)	(2)
Special termination benefits	0	0	0	0
Postretirement benefits settlement	0	1	0	1
Net periodic benefit (income) cost	(2)	2	(4)	4
FPL [Member] | Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	(20)	6	(40)	(12)
FPL [Member] | Postretirement Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	$ (2)	$ 1	$ (3)	$ 3