Proposed Merger (Details) $ in Millions		2 Months Ended	3 Months Ended
	Jul. 16, 2016 USD ($)	Jan. 21, 2015 complaint	Sep. 30, 2016 USD ($)
Business Acquisition [Line Items]
Number of purported class action complaints filed | complaint		8
NextEra Energy, Inc Merger | Scenario, Forecast
Business Acquisition [Line Items]
Recognition of previously disallowed merger expenses			$ 7.8
NextEra Energy, Inc Merger | Subsequent Event
Business Acquisition [Line Items]
Merger contract termination fee	$ 90.0
Maximum expenses paid to party for cancellation of merger	$ 5.0