Employee Retirement Benefits - Net Periodic Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets, Net of Management Fees	7.35%	7.35%	7.35%
Net periodic benefit (income) cost [Abstract]
Service cost	$ 70	$ 66	$ 62
Interest cost	82	83	105
Expected return on plan assets	(276)	(270)	(260)
Amortization of prior service cost (benefit)	(1)	(1)	1
Special termination benefits	35	38	0
Postretirement benefits settlement	0	0	0
Net periodic (income) cost	(90)	(84)	(92)
Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	1	1	2
Interest cost	7	8	13
Expected return on plan assets	0	0	(1)
Amortization of prior service cost (benefit)	(15)	(10)	(2)
Special termination benefits	0	0	0
Postretirement benefits settlement	0	1
Net periodic (income) cost	(7)	0	12
FPL[Member] | Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic (income) cost	(57)	(51)	(58)
FPL[Member] | Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic (income) cost	$ (6)	$ 0	$ 9