Annual report pursuant to Section 13 and 15(d)

Leased Properties and Leases - Significant Leases (Details)

v3.6.0.2
Leased Properties and Leases - Significant Leases (Details)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Pinedale LGS [Member]      
Operating Leased Assets [Line Items]      
Percentage of total leased properties 39.80% 40.00%  
Percentage of leased property revenue 30.40% 42.90% 71.90%
Grand Isle Gathering System [Member]      
Operating Leased Assets [Line Items]      
Percentage of total leased properties 50.00% 50.10%  
Percentage of leased property revenue 59.80% 42.30% 0.00%
Portland Terminal Facility [Member]      
Operating Leased Assets [Line Items]      
Percentage of total leased properties 9.90% 9.60%  
Percentage of leased property revenue 9.70% 13.30% 19.00%
Public Service Company of New Mexico [Member]      
Operating Leased Assets [Line Items]      
Percentage of total leased properties 0.00% 0.00%  
Percentage of leased property revenue 0.00% 1.30% 9.10%