Quarterly report pursuant to Section 13 or 15(d)

Leased Properties and Leases - Significant Leases (Details)

v3.8.0.1
Leased Properties and Leases - Significant Leases (Details)
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Pinedale LGS [Member]          
Operating Leased Assets [Line Items]          
Percentage of total leased properties 39.70%   39.70%   39.80%
Percentage of leased property revenue 31.10% 30.40% 30.80% 30.40%  
Grand Isle Gathering System [Member]          
Operating Leased Assets [Line Items]          
Percentage of total leased properties 50.10%   50.10%   50.00%
Percentage of leased property revenue 59.20% 59.80% 59.50% 59.80%  
Portland Terminal Facility [Member]          
Operating Leased Assets [Line Items]          
Percentage of total leased properties 10.00%   10.00%   9.90%
Percentage of leased property revenue 9.50% 9.70% 9.60% 9.70%