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Landfill Accounting (Narrative) (Details)
$ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 2017
USD ($)
site
$ / T
Sep. 30, 2016
USD ($)
$ / T
Dec. 31, 2016
USD ($)
Landfill Accounting [Line Items]      
Number of landfills owned and operated by company | site 78    
Number of landfills operated, not owned, under life-of-site operating agreements | site 8    
Number of landfills operated under limited-term operating agreements | site 6    
Property and equipment, net | $ $ 4,783,928   $ 4,738,055
Average remaining landfill life based on permitted capacity and projected annual disposal volumes 27 years    
Number of owned landfills the company is seeking to expand | site 11    
Number of landfills operated under life-of-site operating agreements that the company is seeking to expand | site 2    
Average remaining landfill life based on permitted capacity, projected annual disposal volumes and probable expansion capacity 29 years    
Life of Company's owned landfills and landfills operated under life-of-site operating agreements min range 1 year    
Life of Company's owned landfills and landfills operated under life of site operating agreements max range 196 years    
Landfill depletion expense | $ $ 147,071 $ 98,075  
Average rate per ton consumed related to landfill depletion at owned landfills and landfills operated under life-of-site agreements | $ / T 4.55 4.27  
Discount rate for purposes of computing layers for final capping, closure and post-closure obligations 4.75%   4.75%
Inflation rate for purposes of computing layers for final capping, closure and post-closure obligations 2.50%   2.50%
Accretion expense associated with landfill obligations | $ $ 8,757 $ 5,740  
Average rate per ton consumed related to final capping, closure and post-closure landfill accretion expense | $ / T 0.27 0.25  
Restricted asset balance for purposes of securing our performance of future final capping, closure and post-closure obligations | $ $ 55,827   $ 55,388
Landfill [Member]      
Landfill Accounting [Line Items]      
Property and equipment, net | $ $ 2,687,159