Long-term Debt - Components (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term debt, gross	$ 336,180	$ 352,385
Less: Debt issuance costs	(393)	(314)
Less: Current maturities of long-term debt	(87,682)	(99,955)
Long-term debt, excluding current maturities	248,105	252,116
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt, gross	13,200
Revenue equipment notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 290,937	$ 315,163
Weighted average interest rate	4.00%	4.00%
Collateral	$ 293,900	$ 317,200
Mortgages [Member]
Debt Instrument [Line Items]
Long-term debt, gross	25,637	25,977
Collateral	$ 31,400	$ 31,800
Mortgages [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rate	4.17%	4.17%
Mortgages [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rate	6.99%	6.99%
Other Debt [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 6,406	$ 11,245

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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- Definition

Amount of assets pledged to secure a debt instrument.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Weighted average interest rate of debt outstanding.

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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