Quarterly report pursuant to Section 13 or 15(d)

Contingencies (Details)

v3.19.1
Contingencies (Details)
1 Months Ended 2 Months Ended 3 Months Ended 4 Months Ended
Jan. 31, 2019
USD ($)
Feb. 01, 2018
MMBTU / d
Jan. 01, 2018
MMBTU / d
Jul. 31, 2017
MMBTU / d
Jan. 31, 2018
MMBTU / d
Mar. 31, 2019
USD ($)
MMBTU / d
contract
lawsuit
Nov. 30, 2017
MMBTU / d
Nov. 30, 2018
MMBTU / d
Jun. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Mar. 31, 2017
USD ($)
West Virginia activities | Settled Litigation                      
Contingencies                      
Settlement amount | $ $ 3,150,000                    
Doddridge County, Tyler County and Ritchie County, West Virginia | Pending Litigation | Minimum                      
Contingencies                      
Damages sought | $                 $ 100,000    
SJGC                      
Contingencies                      
Natural gas long term purchase contract volume (in MMBtu)/day | MMBTU / d           80,000          
WGL                      
Contingencies                      
Natural gas long term purchase contract volume increase after specified events (in MMBtu)/day | MMBTU / d               530,000      
WGL | Pending Litigation                      
Contingencies                      
Damages sought | $                   $ 40,000,000  
WGL | Pending Litigation | Minimum                      
Contingencies                      
Damages sought | $                     $ 30,000,000
WGL - Braxton, West Virginia                      
Contingencies                      
Natural gas long term purchase contract volume (in MMBtu)/day | MMBTU / d   200,000 500,000                
WGL - Loudoun County, Virginia                      
Contingencies                      
Natural gas long term purchase contract volume increase after specified events (in MMBtu)/day | MMBTU / d               330,000      
Potential Positive Outcome of Litigation | SJGC                      
Contingencies                      
Number of lawsuits | lawsuit           2          
Number of long term gas contracts | contract           2          
Damages sought | $           $ 86,000,000          
Potential Positive Outcome of Litigation | WGL                      
Contingencies                      
Natural gas long term purchase contract volume (in MMBtu)/day | MMBTU / d       500,000 500,000   600,000