Quarterly report pursuant to Section 13 or 15(d)

Transportation and Distribution Revenue - Additional Information (Details)

v3.19.2
Transportation and Distribution Revenue - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended 143 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Oct. 31, 2030
Concentration Risk [Line Items]          
Remaining performance obligation $ 60,800   $ 60,800    
Natural Gas Transportation Contract [Member] | Product and services [Member] | Revenue [Member]          
Concentration Risk [Line Items]          
Concentration percentage 57.60% 66.10% 59.50% 66.30%  
Natural Gas Distribution Contract [Member] | Product and services [Member] | Revenue [Member]          
Concentration Risk [Line Items]          
Concentration percentage 35.00% 27.20% 34.90% 26.80%  
Forecast [Member]          
Concentration Risk [Line Items]          
Recognized performance obligations quarterly         $ 138