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Landfill Accounting (Narrative) (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2017
USD ($)
site
$ / T
Mar. 31, 2016
USD ($)
$ / T
Dec. 31, 2016
USD ($)
Landfill Accounting [Line Items]      
Number of municipal solid waste landfills owned or operated by company 68    
Number of owned landfills that only accept exploration and production waste 11    
Number of owned landfills that only accept construction and demolition, industrial and other non-putrescible waste 14    
Number of landfills owned and operated by company 79    
Number of landfills operated, not owned, under life-of-site operating agreements 8    
Number of landfills operated under limited-term operating agreements 6    
Property and equipment, net | $ $ 4,721,669   $ 4,738,055
Average remaining landfill life based on permitted capacity and projected annual disposal volumes 26 years    
Number of owned landfills the company is seeking to expand 16    
Number of landfills operated under life-of-site operating agreements that the company is seeking to expand 2    
Average remaining landfill life based on permitted capacity, projected annual disposal volumes and probable expansion capacity 32 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 | $ $ 42,988 $ 18,926  
Average rate per ton consumed related to landfill depletion at owned landfills and landfills operated under life-of-site agreements | $ / T 4.55 3.65  
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 | $ $ 2,866 $ 1,061  
Average rate per ton consumed related to final capping, closure and post-closure landfill accretion expense | $ / T 0.30 0.20  
Restricted asset balance for purposes of securing our performance of future final capping, closure and post-closure obligations | $ $ 56,063   $ 55,388
Landfill [Member]      
Landfill Accounting [Line Items]      
Property and equipment, net | $ $ 2,717,100