Quarterly report pursuant to Section 13 or 15(d)

Transportation and Distribution Revenue - Additional Information (Details)

v3.19.3
Transportation and Distribution Revenue - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended 143 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Oct. 31, 2030
Dec. 31, 2018
Concentration Risk [Line Items]            
Remaining performance obligation $ 59,500   $ 59,500      
Contract asset balance $ 74   $ 74     $ 181
Natural gas transportation contracts | Product and services | Revenue            
Concentration Risk [Line Items]            
Concentration percentage 52.70% 60.30% 57.50% 64.20%    
Natural gas distribution contracts | Product and services | Revenue            
Concentration Risk [Line Items]            
Concentration percentage 39.20% 24.80% 36.20% 26.10%    
Forecast            
Concentration Risk [Line Items]            
Recognized performance obligations quarterly         $ 138