Annual report pursuant to Section 13 and 15(d)

Operating Leases (Details)

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Operating Leases (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Operating Leases [Abstract]      
Operating lease renewal option, minimum (in years) 1 year    
Operating lease renewal option, maximum (in years) 10 years    
Operating lease original term, for tractors, trucks and trailers, minimum (in years) 3 years    
Operating lease original term, for tractors, trucks and trailers, maximum (in years) 6 years    
Sublease rental income $ 813 $ 770 $ 556
Expected future sublease rental income 131    
Operating Leases, Future Minimum Payments Due [Abstract]      
2013 19,371    
2014 17,700    
2015 14,051    
2016 9,737    
2017 5,312    
Thereafter 5,723    
Total $ 71,894