Exit and Termination Costs - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Restructuring Cost And Reserve [Line Items]
Restructuring Charges	$ 13,714	$ 1,595
Severance costs	509	1,595
North Louisiana
Restructuring Cost And Reserve [Line Items]
Accretion expense	13,000
Exit cost	471,900
Pennsylvania
Restructuring Cost And Reserve [Line Items]
Exit cost	210	0
Pennsylvania | Capacity Releases on Transportation Pipelines
Restructuring Cost And Reserve [Line Items]
Exit cost	$ 9,000
Northwest Pennsylvania
Restructuring Cost And Reserve [Line Items]
Severance costs		$ 1,600