Quarterly report pursuant to Section 13 or 15(d)

Transportation and Distribution Revenue - Additional Information (Details)

v3.19.1
Transportation and Distribution Revenue - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended 143 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Oct. 31, 2030
Concentration Risk [Line Items]      
Remaining performance obligation $ 62,100    
Natural Gas Transportation Contract [Member] | Product and services [Member] | Revenue [Member]      
Concentration Risk [Line Items]      
Concentration percentage 61.40% 66.50%  
Natural Gas Distribution Contract [Member] | Product and services [Member] | Revenue [Member]      
Concentration Risk [Line Items]      
Concentration percentage 34.80% 26.40%  
Forecast [Member]      
Concentration Risk [Line Items]      
Recognized performance obligations quarterly     $ 138