Annual report pursuant to Section 13 and 15(d)

Equity Method Investments - Significant Entities, Accounted for Using Equity Method (Details)

v3.10.0.1
Equity Method Investments - Significant Entities, Accounted for Using Equity Method (Details) - USD ($)
$ in Millions
 9 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Dec. 31, 2016
Balance Sheet      
Current assets $ 257 $ 137  
Total assets 4,104 3,265  
Current liabilities 116 76  
Total liabilities 1,001 366  
Members’ equity 3,103 2,899  
Income Statement      
Revenue 217 273 $ 308
Income from continuing operations 19 (52) 22
Net income 19 (52) 22
Buckeye Wind Energy Class B Holdings, LLC [Member]      
Balance Sheet      
Current assets 4 3  
Total assets 280 286  
Current liabilities 3 1  
Total liabilities 13 11  
Members’ equity 267 275  
Income Statement      
Revenue 10 12 13
Income from continuing operations (5) (8) (6)
Net income (5) (8) (6)
MM Solar Parent, LLC [Member]      
Balance Sheet      
Current assets 4 3  
Total assets 84 85  
Current liabilities 5 5  
Total liabilities 33 36  
Members’ equity 51 49  
Income Statement      
Revenue 8 11 12
Income from continuing operations 4 4 5
Net income 4 4 5
Helix Fund I, LLC [Member]      
Balance Sheet      
Current assets 1 1  
Total assets 27 28  
Current liabilities 0 0  
Total liabilities 0 0  
Members’ equity 27 28  
Income Statement      
Revenue 2 2 0
Income from continuing operations 1 1 0
Net income 1 1 0
Other Investments [Member]      
Balance Sheet      
Current assets 248 130  
Total assets 3,713 2,866  
Current liabilities 108 70  
Total liabilities 955 319  
Members’ equity 2,758 2,547  
Income Statement      
Revenue 197 248 283
Income from continuing operations 19 (49) 23
Net income $ 19 $ (49) $ 23