Restructuring and Other - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Jun. 30, 2018
Restructuring Cost And Reserve [Line Items]
One-time employee termination expenses and estimated losses		$ 34.0
Expenses from restructuring energy generation and storage segment		56.1
Impairment loss		$ 13.3
Scenario Forecast [Member]
Restructuring Cost And Reserve [Line Items]
Employee termination expenses paid	$ 26.2