Annual report pursuant to Section 13 and 15(d)

Our Portfolio - Schedule of Equity Method Investments (Detail)

v3.6.0.2
Our Portfolio - Schedule of Equity Method Investments (Detail) - USD ($)
$ in Millions
Dec. 31, 2016
Oct. 31, 2016
Jun. 30, 2016
Dec. 31, 2015
Apr. 30, 2015
Oct. 31, 2014
Schedule of Equity Method Investments [Line Items]            
Project investment amount $ 363          
Strong Upwind Holdings One LLC [Member] | JP Morgan [Member] | Renewable Energy Projects [Member]            
Schedule of Equity Method Investments [Line Items]            
Project investment amount           $ 97
Strong Upwind Holdings Two LLC [Member] | JP Morgan [Member] | Renewable Energy Projects [Member]            
Schedule of Equity Method Investments [Line Items]            
Project investment amount         $ 30  
Strong Upwind Holdings Three LLC [Member] | JP Morgan [Member] | Renewable Energy Projects [Member]            
Schedule of Equity Method Investments [Line Items]            
Project investment amount       $ 66    
Buckeye Wind Energy Class B Holdings LLC [Member] | Invenergy [Member] | Renewable Energy Projects [Member]            
Schedule of Equity Method Investments [Line Items]            
Project investment amount       $ 70    
MM Solar Holdings LLC [Member] | AES [Member] | Renewable Energy Projects [Member]            
Schedule of Equity Method Investments [Line Items]            
Project investment amount     $ 26      
Invenergy Gunsight Mountain Holdings LLC [Member] | Invenergy [Member] | Renewable Energy Projects [Member]            
Schedule of Equity Method Investments [Line Items]            
Project investment amount   $ 40        
Other Transactions [Member] | Various [Member] | Renewable Energy Projects [Member]            
Schedule of Equity Method Investments [Line Items]            
Project investment amount $ 34