Summary of Significant Accounting Policies (Reconciliation of Final Capping, Closure and Post-Closure Liability Balance) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Business [Abstract]
Final capping, closure and post-closure liability at the beginning of the period	$ 291,474	$ 251,782
Liabilities adjustments	2,490	19,846
Accretion expense associated with landfill obligations	14,874	14,251
Closure payments	(6,488)	(5,059)
Assumption of closure liabilities from acquisitions	2,136	8,707
Disposition of closure liabilities from divested operations	(3,413)
Foreign currency translation adjustment	823	1,947
Final capping, closure and post-closure liability at the end of the period	$ 301,896	$ 291,474