Employee Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	$ 16	$ 18
Interest cost	26	24
Expected return on plan assets	(65)	(63)
Amortization of prior service benefit	0	0
Net periodic benefit (income) cost	(23)	(21)
Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	1	1
Interest cost	3	3
Expected return on plan assets	0	0
Amortization of prior service benefit	(1)	0
Net periodic benefit (income) cost	3	4
FPL [Member] | Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	(15)	(14)
FPL [Member] | Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	$ 2	$ 3