Annual report pursuant to Section 13 and 15(d)

Significant Accounting Policies (Narrative) (Details)

v2.4.0.6
Significant Accounting Policies (Narrative) (Details) (USD $)
0 Months Ended 12 Months Ended
Sep. 07, 2012
Aug. 23, 2010
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Significant Accounting Policies [Line Items]          
Stockholders' Equity Note, Stock Split, Conversion Ratio 1.5 1.5      
Debt and Capital Lease Obligations     $ 240,407,000 $ 269,185,000  
Depreciation expenses including capital leases     109,800,000 89,900,000 79,400,000
Increase in income from continuing operations         12,700,000
Increase in net income         7,700,000
Other intangible assets     8,100,000 8,100,000  
Accumulated amortization of intangible assets     5,700,000 4,700,000  
Amortization expense     900,000 900,000 900,000
Maximum self-insured long-term disability claims for employees per month       3,000  
Last payment date of self-insured long-term disability claims for salaried employees         April 2, 2010
Last payment date of self-insured long-term disability claims for non-salaried employees       July 1, 2011  
Self-insurance reserve     93,500,000 86,000,000  
Long-term portions of self insurance reserve     59,500,000 50,100,000  
Advertising expense     11,000,000 8,300,000 6,300,000
Long-term Debt, Fair Value     247,900,000 276,600,000  
Trailers [Member]
         
Significant Accounting Policies [Line Items]          
Estimated average useful lives of asset, years     15    
Estimated previous useful lives of asset, years     12    
Tractors [Member]
         
Significant Accounting Policies [Line Items]          
Estimated average useful lives of asset, years     9    
Estimated previous useful lives of asset, years     7    
Group Health Claims [Member]
         
Significant Accounting Policies [Line Items]          
Insurance maximum, per occurrence     400,000    
Self insurance additional coverage     200,000    
Workers Compensation Claims [Member]
         
Significant Accounting Policies [Line Items]          
Insurance maximum, per occurrence     1,000,000    
Cargo Loss And Damage Claims [Member]
         
Significant Accounting Policies [Line Items]          
Insurance maximum, per occurrence     100,000    
Bodily Injury And Property Damage [Member]
         
Significant Accounting Policies [Line Items]          
Insurance maximum, per occurrence     $ 2,750,000