Income Taxes - Components of Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Federal:
Current	$ 167	$ 30	$ 100
Deferred	115	1,153	(1,047)
Total federal	282	1,183	(947)
State:
Current	23	63	88
Deferred	143	330	199
Total state	166	393	287
Total income tax expense (benefit)	448	1,576	(660)
FPL[Member]
Federal:
Current	348	251	168
Deferred	(29)	134	776
Total federal	319	385	944
State:
Current	49	91	29
Deferred	73	63	133
Total state	122	154	162
Total income tax expense (benefit)	$ 441	$ 539	$ 1,106