XML 73 R59.htm IDEA: XBRL DOCUMENT v3.8.0.1
SIGNIFICANT ACCOUNTING POLICIES (Landfill Accounting) (Details)
$ in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
expansion
landfill_site
service_location
cubic_yard
Dec. 31, 2016
USD ($)
cubic_yard
Dec. 31, 2015
USD ($)
cubic_yard
Property, Plant and Equipment [Line Items]      
Application approvals, acceptance period 5 years    
Number of unpermitted expansions | expansion 2    
Number of service locations | service_location 2    
Percentage of airspace remaining 18.40%    
Landfill sites | landfill_site 11    
Remaining highly probable airspace 31,113,000    
Permitted, but not highly probable airspace 0 0  
Remaining Airspace Capacity [Roll Forward]      
Remaining capacity, beginning of period (cubic yards) 32,228,000 29,786,000 30,544,000
Addition of highly probable airspace, net (cubic yards) 0 3,464,000 516,000
Consumed (cubic yards) (1,115,000) (1,022,000) (1,274,000)
Remaining capacity, end of period (cubic yards) 31,113,000 32,228,000 29,786,000
Landfill final closure and post-closure liabilities | $ $ 32.4 $ 30.6  
Regulatory post-closure period for landfill 30 years    
Asset retirement obligations, inflation rate 1.02% 1.02%  
Asset retirement obligations, risk free rate 6.32% 6.23%  
Non-landfill closure and post-closure liabilities | $ $ 28.6 $ 27.7  
Minimum      
Remaining Airspace Capacity [Roll Forward]      
Non-landfill closure and post-closure liabilities, period 10 years    
Maximum      
Remaining Airspace Capacity [Roll Forward]      
Non-landfill closure and post-closure liabilities, period 30 years    
Landfill assets      
Property, Plant and Equipment [Line Items]      
Amortization | $ $ 9.5 $ 9.7 $ 11.2
Non-commercial landfills      
Property, Plant and Equipment [Line Items]      
Landfill sites | landfill_site 2    
Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 25,403,000    
Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 5,710,000    
Altair | Texas      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 3 years    
Remaining highly probable airspace 438,000    
Altair | Texas | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 438,000    
Altair | Texas | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0    
Buttonwillow | California      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 20 years    
Remaining highly probable airspace 6,459,000    
Buttonwillow | California | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 6,459,000    
Buttonwillow | California | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0    
Deer Park | Texas      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 5 years    
Remaining highly probable airspace 198,000    
Deer Park | Texas | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 198,000    
Deer Park | Texas | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0    
Deer Trail | Colorado      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 33 years    
Remaining highly probable airspace 1,812,000    
Deer Trail | Colorado | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 1,812,000    
Deer Trail | Colorado | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0    
Grassy Mountain | Utah      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 59 years    
Remaining highly probable airspace 5,121,000    
Grassy Mountain | Utah | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 291,000    
Grassy Mountain | Utah | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 4,830,000    
Kimball | Nebraska      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 8 years    
Remaining highly probable airspace 211,000    
Kimball | Nebraska | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 211,000    
Kimball | Nebraska | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0    
Lambton | Ontario      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 53 years    
Remaining highly probable airspace 4,882,000    
Lambton | Ontario | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 4,882,000    
Lambton | Ontario | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0    
Lone Mountain | Oklahoma      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 24 years    
Remaining highly probable airspace 4,402,000    
Lone Mountain | Oklahoma | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 4,402,000    
Lone Mountain | Oklahoma | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0    
Ryley | Alberta      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 8 years    
Remaining highly probable airspace 1,231,000    
Ryley | Alberta | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 351,000    
Ryley | Alberta | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 880,000    
Sawyer | North Dakota      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 84 years    
Remaining highly probable airspace 3,627,000    
Sawyer | North Dakota | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 3,627,000    
Sawyer | North Dakota | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0    
Westmorland | California      
Property, Plant and Equipment [Line Items]      
Remaining Lives (Years) 64 years    
Remaining highly probable airspace 2,732,000    
Westmorland | California | Permitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 2,732,000    
Westmorland | California | Unpermitted      
Property, Plant and Equipment [Line Items]      
Remaining highly probable airspace 0