XML 21 R42.htm IDEA: XBRL DOCUMENT v2.4.0.6
Commitments and Contingencies (Details) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]      
2013 $ 43,855,000    
2014 35,310,000    
2015 25,814,000    
2016 8,427,000    
2017 5,558,000    
Thereafter 9,028,000    
Total Due 127,992,000    
Rent expense on operating leases 46,100,000 39,400,000 37,900,000
Residual value of certain leased tractors $ 29,400,000    
Minimum [Member]
     
Property, Plant and Equipment [Line Items]      
Term of Lease 3 months    
Maximum [Member]
     
Property, Plant and Equipment [Line Items]      
Term of Lease 65 months