Contingencies (Details)				2 Months Ended	4 Months Ended	19 Months Ended
	Jun. 20, 2019 USD ($)	Feb. 01, 2018 MMBTU / d	Jan. 31, 2018 MMBTU / d	Jan. 31, 2018 MMBTU / d	Nov. 30, 2017 MMBTU / d	Jul. 31, 2017 MMBTU / d	Jun. 30, 2020 USD ($)	Nov. 30, 2018 MMBTU / d	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)
Doddridge County, Tyler County and Ritchie County, West Virginia | Minimum
Contingencies
Damages sought | $							$ 100,000
WGL
Contingencies
Damages awarded | $	$ 96,000,000
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 | WGL
Contingencies
Natural gas long term purchase contract volume (in MMBtu)/day | MMBTU / d				500,000	600,000	500,000