Employee Retirement Benefits - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Target asset allocations [Abstract]
Defined contribution expense	$ 52	$ 63	$ 59
FPL [Member]
Target asset allocations [Abstract]
Defined contribution expense	32	40	$ 37
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	325	321
Other Benefits [Member] | FPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	222	230
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	$ 1,177	$ 1,155
Weighted-average assumptions used to determine benefit obligations [Abstract]
Discount rate (in hundredths)	4.09%	4.35%
Salary increase (in hundredths)	4.10%	4.10%
Pension Benefits [Member] | FPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan	$ 1,301	$ 1,243
Pension Benefits [Member] | Equity Securities [Member]
Target asset allocations [Abstract]
Equity investments, target allocation percentage (in hundredths)	45.00%
Pension Benefits [Member] | Debt Securities [Member]
Target asset allocations [Abstract]
Equity investments, target allocation percentage (in hundredths)	32.00%
Pension Benefits [Member] | Alternative Investments [Member]
Target asset allocations [Abstract]
Equity investments, target allocation percentage (in hundredths)	13.00%
Pension Benefits [Member] | Convertible Securities [Member]
Target asset allocations [Abstract]
Equity investments, target allocation percentage (in hundredths)	10.00%