Employee Retirement Benefits - Net Periodic Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost Recognized	$ 63	$ 59	$ 46
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	70	61	72
Interest cost	97	101	94
Expected return on plan assets	(253)	(241)	(238)
Amortization of prior service cost (benefit)	1	5	7
Amortization of losses	0	0	2
Special termination benefits	0	0	46
Net periodic benefit (income) cost	(85)	(74)	(17)
Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	3	3	4
Interest cost	13	16	14
Expected return on plan assets	(1)	(1)	(1)
Amortization of prior service cost (benefit)	(3)	(3)	(2)
Amortization of losses	2	0	2
Special termination benefits	0	0	0
Net periodic benefit (income) cost	14	15	17
FPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost Recognized	40	37	30
FPL [Member] | Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	(55)	(47)	(7)
FPL [Member] | Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Net periodic benefit (income) cost	$ 11	$ 11	$ 13