Employee Retirement Benefits - Plan Assets, Benefit Obligations and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in pension plan assets:
Plan assets, beginning balance	$ 3,806
Plan assets, ending balance	4,800	$ 3,806
Other Postretirement Benefits Plan [Member]
Change in pension benefit obligation:
Service cost	1	1	$ 1
Interest cost	9	7	8
Special termination benefits	0	0	0
Funded status:
Prepaid (accrued) benefit cost	(313)	(226)
Pension Benefits [Member]
Change in pension plan assets:
Plan assets, beginning balance	3,806	4,020
Actual return on plan assets	736	(69)
Benefit payments	(235)	(160)
Acquisitions	493	15
Plan assets, ending balance	4,800	3,806	4,020
Change in pension benefit obligation:
Obligation, beginning balance	2,522	2,593
Service cost	80	70	66
Interest cost	114	82	83
Acquisitions	503	15
Special termination benefits	19	35	38
Plan amendments	3	0
Actuarial losses (gains) - net	357	(113)
Benefit payments	(235)	(160)
Obligation, ending balance	3,363	2,522	$ 2,593
Funded status:
Prepaid (accrued) benefit cost	1,437	1,284
Accumulated benefit obligation	3,281	2,479
FPL[Member] | Other Postretirement Benefits Plan [Member]
Funded status:
Prepaid (accrued) benefit cost	(167)	(187)
FPL[Member] | Pension Benefits [Member]
Funded status:
Prepaid (accrued) benefit cost	$ 1,477	$ 1,407