v3.19.1
Divestitures (Details) - Subsequent Event [Member]
$ in Millions
3 Months Ended
Sep. 30, 2019
USD ($)
Apr. 08, 2019
MW
Garrison Energy Center and RockGen Energy LLC [Member]    
Business Acquisition [Line Items]    
Ownership percentage of acquiree   100.00%
Proceeds from Sale of Productive Assets | $ $ 360  
Garrison Energy Center LLC [Member]    
Business Acquisition [Line Items]    
Power generation capacity   309
RockGen Energy LLC [Member]    
Business Acquisition [Line Items]    
Power generation capacity   503