Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
Other Non-Current Assets - Equity Method Investments (Details)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2017
USD ($)
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
mi
Jun. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Investment [Line Items]          
Equity method investment $ 65,000   $ 65,000   $ 10,000
Other—related party 1,000 $ 0 1,000 $ 0  
Accounts receivable—related party 1,000   1,000   $ 0
Midship Holdings [Member]          
Investment [Line Items]          
Equity method investment 55,000   55,000    
O&M Services [Member] | Midship Pipeline [Member] | Service Agreements [Member]          
Investment [Line Items]          
Other—related party 1,000   1,000    
Accounts receivable—related party 1,000   $ 1,000    
CCL [Member] | Midship Pipeline [Member] | Natural Gas Transportation Agreement [Member]          
Investment [Line Items]          
Long-term Purchase Commitment, Period     10 years    
EIG [Member] | Maximum [Member]          
Investment [Line Items]          
Investment Company, Financial Commitment to Investee, Future Amount $ 500,000   $ 500,000    
Midship Pipeline [Member] | Midship Project [Member]          
Investment [Line Items]          
Length Of Natural Gas Pipeline | mi     230