Annual report pursuant to Section 13 and 15(d)

Other Non-Current Assets - Equity Method Investments (Details)

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Other Non-Current Assets - Equity Method Investments (Details)
12 Months Ended
Dec. 31, 2018
USD ($)
mi
Dec. 31, 2017
USD ($)
May 31, 2018
USD ($)
Investment [Line Items]      
Equity method investment $ 94,000,000 $ 64,000,000  
Accounts receivable—related party 4,000,000 2,000,000  
Midship Holdings [Member]      
Investment [Line Items]      
Equity method investment 85,000,000 55,000,000  
O&M Services [Member] | Midship Pipeline [Member] | Service Agreements [Member]      
Investment [Line Items]      
Other—related party 12,000,000 3,000,000  
Accounts receivable—related party $ 4,000,000 $ 2,000,000  
CCL [Member] | Midship Pipeline [Member] | Natural Gas Transportation Agreement [Member]      
Investment [Line Items]      
Long-term Purchase Commitment, Period 10 years    
Midship Pipeline [Member]      
Investment [Line Items]      
Length of Natural Gas Pipeline | mi 200    
Midship Pipeline [Member] | CCL [Member] | Midship Pipeline Letter of Credit [Member]      
Investment [Line Items]      
Letter of Credit, Maximum Borrowing Capacity     $ 16,000,000
Letters of credit issued $ 0    
EIG [Member] | Maximum [Member]      
Investment [Line Items]      
Investment Company, Financial Commitment to Investee, Future Amount $ 500,000,000