Accident and Workers' Compensation Insurance Liabilities	12 Months Ended
Dec. 31, 2011
Accident and Workers' Compensation Insurance Liabilities [Abstract]
Other Liabilities Disclosure [Text Block]	Accident and Workers’ Compensation Insurance Liabilities The Company acts as a self-insurer for auto liability involving property damage, personal injury, or cargo up to $2.0 million for any individual claim. Liabilities in excess of these amounts are covered by insurance up to $55.0 million in the aggregate for the coverage period. The Company increased the retention amount from $1.0 million to $2.0 million for each claim occurring on or after April 1, 2009. The Company acts as a self-insurer for workers’ compensation liability up to $1.0 million for any individual claim. Liabilities in excess of this amount are covered by insurance. The State of Iowa initially required the Company to deposit $0.7 million into a trust fund as part of the self-insurance program. Earnings on this account become part of the required deposit and as of December 31, 2011 total deposits in this account were $1.3 million. This deposit is in municipal bonds classified as held-to-maturity and is recorded in other assets on the consolidated balance sheet. In addition, the Company has provided its insurance carriers with letters of credit totaling approximately $3.1 million in connection with its liability and workers’ compensation insurance arrangements. There were no outstanding balances due on the letters of credit at December 31, 2011 or 2010. Accident and workers’ compensation accruals include the estimated settlements, settlement expenses and an estimate for claims incurred but not yet reported for property damage, personal injury and public liability losses from vehicle accidents and cargo losses as well as workers’ compensation claims for amounts not covered by insurance. Accident and workers’ compensation accruals are based upon individual case estimates, including reserve development, and estimates of incurred-but-not-reported losses based upon the Company's own historical experience and industry claim trends. Since the reported liability is an estimate, the ultimate liability may be more or less than reported. If adjustments to previously established accruals are required, such amounts are included in operating expenses in the current period. These accruals are recorded on an undiscounted basis. Estimated claim payments to be made within one year of the balance sheet date have been classified as insurance accruals within current liabilities as of December 31, 2011 and 2010.

Accident and Workers’ Compensation Insurance Liabilities

The Company acts as a self-insurer for auto liability involving property damage, personal injury, or cargo up to $2.0 million for any individual claim. Liabilities in excess of these amounts are covered by insurance up to $55.0 million in the aggregate for the coverage period. The Company increased the retention amount from $1.0 million to $2.0 million for each claim occurring on or after April 1, 2009.

The Company acts as a self-insurer for workers’ compensation liability up to $1.0 million for any individual claim. Liabilities in excess of this amount are covered by insurance. The State of Iowa initially required the Company to deposit $0.7 million into a trust fund as part of the self-insurance program. Earnings on this account become part of the required deposit and as of December 31, 2011 total deposits in this account were $1.3 million. This deposit is in municipal bonds classified as held-to-maturity and is recorded in other assets on the consolidated balance sheet. In addition, the Company has provided its insurance carriers with letters of credit totaling approximately $3.1 million in connection with its liability and workers’ compensation insurance arrangements. There were no outstanding balances due on the letters of credit at December 31, 2011 or 2010.

Accident and workers’ compensation accruals include the estimated settlements, settlement expenses and an estimate for claims incurred but not yet reported for property damage, personal injury and public liability losses from vehicle accidents and cargo losses as well as workers’ compensation claims for amounts not covered by insurance. Accident and workers’ compensation accruals are based upon individual case estimates, including reserve development, and estimates of incurred-but-not-reported losses based upon the Company's own historical experience and industry claim trends. Since the reported liability is an estimate, the ultimate liability may be more or less than reported. If adjustments to previously established accruals are required, such amounts are included in operating expenses in the current period. These accruals are recorded on an undiscounted basis. Estimated claim payments to be made within one year of the balance sheet date have been classified as insurance accruals within current liabilities as of December 31, 2011 and 2010.