Commitments And Contingencies (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Aggregate amount accrued for loss contingencies	$ 21,769
Amount probable of recovery through insurance	7,685
Insurance reserve for employee medical benefit program	$ 1,852
Peoples Gas Acquisition [Member]
Commitments And Contingencies [Line Items]
Pipeline term	7 years
Pipeline cost	$ 120,000
Customer rate credits	$ 23,000