Employee Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	$ 20	$ 18
Interest cost	29	20
Expected return on plan assets	(79)	(69)
Amortization of prior service benefit	0	0
Net periodic benefit (income) cost	(30)	(31)
Postretirement Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	0	0
Interest cost	3	2
Expected return on plan assets	0	0
Amortization of prior service benefit	(4)	(4)
Net periodic benefit (income) cost	(1)	(2)
FPL [Member] | Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	(18)	(20)
FPL [Member] | Postretirement Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	$ (1)	$ (2)