Variable Interest Entities - Schedule of Variable Interest Entities (Details) - USD ($)
$ in Millions
Sep. 30, 2019
Dec. 31, 2018
Sep. 30, 2018
Current assets:      
Cash and cash equivalents $ 106 $ 101  
Restricted cash 0 4  
Trade receivables 65 50  
Prepaid expenses 16 18  
Other current assets 22 15  
Total current assets 241 211  
Restricted cash 13 18  
Construction in progress 500 259  
Property, plant and equipment, net 3,917 4,119 $ 4,110
Unconsolidated investments 281 270 372
Deferred financing costs, net 7 8  
Intangible assets, net 211 219  
Other assets 101 34  
Total assets 5,396 5,294 $ 5,372
Current liabilities:      
Accounts payable and other accrued liabilities 66 67  
Accrued construction costs 51 27  
Current portion of long-term debt, net 329 56  
Other current liabilities 27 11  
Total current liabilities 717 478  
Long-term debt, net 2,172 2,004  
Intangible liability, net 45 56  
Asset retirement obligations 213 185  
Other long-term liabilities 128 71  
Deferred revenue 26 26  
Total liabilities 3,567 3,135  
Variable Interest Entity, Primary Beneficiary      
Current assets:      
Cash and cash equivalents 32 36  
Restricted cash 0 4  
Trade receivables 19 13  
Prepaid expenses 3 6  
Other current assets 4 2  
Total current assets 58 61  
Restricted cash 2 3  
Construction in progress 0 1  
Property, plant and equipment, net 2,083 2,156  
Unconsolidated investments 54 0  
Deferred financing costs, net 1 2  
Intangible assets, net 11 12  
Other assets 18 12  
Total assets 2,227 2,247  
Current liabilities:      
Accounts payable and other accrued liabilities 26 27  
Accrued construction costs 0 1  
Current portion of long-term debt, net 5 4  
Other current liabilities 5 5  
Total current liabilities 36 37  
Long-term debt, net 150 149  
Intangible liability, net 45 48  
Asset retirement obligations 59 57  
Other long-term liabilities 42 36  
Deferred revenue 26 26  
Total liabilities $ 358 $ 353