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)

v3.8.0.1
Equity Method Investments - Summary of Consolidated Financial Position and Results of Operations of Significant Entities, Accounted for Using Equity Method (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Balance Sheet    
Current assets $ 103 $ 81
Total assets 3,085 3,080
Current liabilities 72 44
Total liabilities 372 299
Members’ equity 2,713 2,781
Income Statement    
Revenue 295 287
Income from continuing operations (26) 17
Net income (26) 17
Buckeye Wind Energy Class B Holdings, LLC [Member]    
Balance Sheet    
Current assets 3 5
Total assets 286 297
Current liabilities 1 1
Total liabilities 11 7
Members’ equity 275 290
Income Statement    
Revenue 12 13
Income from continuing operations (8) (6)
Net income (8) (6)
MM Solar Parent, LLC [Member]    
Balance Sheet    
Current assets 3 3
Total assets 85 88
Current liabilities 5 4
Total liabilities 37 40
Members’ equity 48 48
Income Statement    
Revenue 11 12
Income from continuing operations 4 5
Net income 4 5
Helix Fund I, LLC [Member]    
Balance Sheet    
Current assets 1 0
Total assets 28 11
Current liabilities 0 0
Total liabilities 0 0
Members’ equity 28 11
Income Statement    
Revenue 2 0
Income from continuing operations 1 0
Net income 1 0
Other Investments [Member]    
Balance Sheet    
Current assets 96 73
Total assets 2,686 2,684
Current liabilities 66 39
Total liabilities 324 252
Members’ equity 2,362 2,432
Income Statement    
Revenue 270 262
Income from continuing operations (23) 18
Net income $ (23) $ 18