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
 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Balance Sheet      
Current assets $ 38   $ 36
Total assets 1,273   1,316
Current liabilities 24   31
Total liabilities 77   103
Members’ equity 1,196   1,213
Income Statement      
Revenue 45 $ 57  
Income from continuing operations 19 7  
Net income 19 7  
Buckeye Wind Energy Class B Holdings, LLC [Member]      
Balance Sheet      
Current assets 3   3
Total assets 281   286
Current liabilities 1   1
Total liabilities 11   11
Members’ equity 270   275
Income Statement      
Revenue 7 6  
Income from continuing operations (2) (4)  
Net income (2) (4)  
MM Solar Parent, LLC [Member]      
Balance Sheet      
Current assets 3   3
Total assets 85   85
Current liabilities 5   5
Total liabilities 34   37
Members’ equity 51   48
Income Statement      
Revenue 6 6  
Income from continuing operations 3 3  
Net income 3 3  
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 1 1  
Income from continuing operations 0 0  
Net income 0 0  
Other Investments [Member]      
Balance Sheet      
Current assets 31   29
Total assets 879   917
Current liabilities 18   25
Total liabilities 32   55
Members’ equity 847   $ 862
Income Statement      
Revenue 31 44  
Income from continuing operations 18 8  
Net income $ 18 $ 8