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Commitments and Contingencies - Additional Information (Detail)
1 Months Ended 6 Months Ended 12 Months Ended
Apr. 30, 2011
USD ($)
May 31, 2009
USD ($)
Jun. 30, 2016
USD ($)
a
Dec. 31, 2015
USD ($)
Feb. 29, 2016
Resident
Jan. 29, 2016
Expera Old Town LLC [Member]            
Contingencies And Commitments [Line Items]            
Reserve related with settlement     $ 1,355,000 $ 2,616,000    
Contract settlement charge       1,940,000    
Reserve related with settlement       $ 676,000    
Reserve for legal costs     34,000      
Expera Old Town LLC [Member] | Upon Execution of SA [Member]            
Contingencies And Commitments [Line Items]            
Litigation settlement     1,250,000      
Expera Old Town LLC [Member] | Five years following execution of SA [Member]            
Contingencies And Commitments [Line Items]            
Litigation settlement     350,000      
Southbridge Recycling and Disposal Park, Inc [Member]            
Contingencies And Commitments [Line Items]            
Number of resident's homes representing legal suit | Resident         40  
Maximum [Member] | Expera Old Town LLC [Member]            
Contingencies And Commitments [Line Items]            
Annual fuel replacement fee     $ 2,000,000      
Contract maturity year     2036      
Minimum [Member]            
Contingencies And Commitments [Line Items]            
Investigative expenditure incurred, expect recovery amount     $ 1,548      
Potsdam Environmental Remediation Liability [Member]            
Contingencies And Commitments [Line Items]            
Scrap yard and solid waste transfer station | a     25      
Estimate of total undiscounted costs associated with implementing the preferred remedies $ 12,130,000 $ 10,219,000        
Remediation activities, participant share percentage           15.00%
Risk free interest rate     1.80%