Segment Information (Details)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Percentage of operating revenues derived from the sale of electricity (in hundredths)	93.00%	90.00%	92.00%
Maximum percentage of operating revenues from foreign sources (in hundredths)	2.00%	2.00%	2.00%
Maximum percentage of long-lived assets located in foreign countries (in hundredths)	3.00%	3.00%

The maximum percentage of long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets, located in foreign countries in total in which the entity holds assets.

No definition available.

Name:	nee_MaximumPercentageOfLongLivedAssetsLocatedInForeignCountries
Namespace Prefix:	nee_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant