Income Taxes - Narrative (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Tax Cuts and Jobs Act of 2017, change in tax rate, deferred tax liability, income tax expense (benefit)		$ 6,500
FPL[Member]
Operating Loss Carryforwards [Line Items]
Tax Cuts and Jobs Act of 2017, change in tax rate, deferred tax liability, income tax expense (benefit)		4,500
NEER [Member]
Operating Loss Carryforwards [Line Items]
Tax Cuts and Jobs Act of 2017, change in tax rate, deferred tax liability, income tax expense (benefit)		$ 2,000
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2018-02 [Member]
Operating Loss Carryforwards [Line Items]
Reclassification of tax benefits from AOCI to retained earnings	$ 16