Quarterly report pursuant to Section 13 or 15(d)

Equity Method Investments - Summary of Consolidated Financial Position and Results of Operations of Significant Entities, Accounted for Using Equity Method (Details)

v3.10.0.1
Equity Method Investments - Summary of Consolidated Financial Position and Results of Operations of Significant Entities, Accounted for Using Equity Method (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Balance Sheet      
Current assets $ 16   $ 23
Total assets 605   618
Current liabilities 19   28
Total liabilities 82   93
Members’ equity 523   525
Income Statement      
Revenue 12 $ 11  
Income from continuing operations (1) (5)  
Net income (1) (5)  
Buckeye Wind Energy Class B Holdings, LLC [Member]      
Balance Sheet      
Current assets 3   3
Total assets 283   286
Current liabilities 1   1
Total liabilities 11   11
Members’ equity 272   275
Income Statement      
Revenue 4 3  
Income from continuing operations (1) (2)  
Net income (1) (2)  
MM Solar Parent, LLC [Member]      
Balance Sheet      
Current assets 2   3
Total assets 84   85
Current liabilities 5   5
Total liabilities 35   37
Members’ equity 49   48
Income Statement      
Revenue 3 3  
Income from continuing operations 1 1  
Net income 1 1  
Helix Fund I, LLC [Member]      
Balance Sheet      
Current assets 1   1
Total assets 28   28
Current liabilities 0   0
Total liabilities 0   0
Members’ equity 28   28
Income Statement      
Revenue 0 0  
Income from continuing operations 0 0  
Net income 0 0  
Other Investments [Member]      
Balance Sheet      
Current assets 10   16
Total assets 210   219
Current liabilities 13   22
Total liabilities 36   45
Members’ equity 174   $ 174
Income Statement      
Revenue 5 5  
Income from continuing operations (1) (4)  
Net income $ (1) $ (4)