Approximate number of capital leased units converted to operating leased units.

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Represents the number of leased units related to the sale leaseback transaction.

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Represents the number of units in the sale leaseback transaction.

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Term of sale leaseback arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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Amount of increase (decrease) in debt instruments, classified as other.

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

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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No definition available.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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Weighted average interest rate of long-term debt outstanding.

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No definition available.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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Minimum amount of other commitment maturing in the next fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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Amount of long-term debt classified as other.

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Amount of long-term debt classified as other, payable within one year or the operating cycle, if longer.

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The portion of the gain that will be recorded as income or a reduction in rent expense in future periods less amounts recognized in the current period.

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Note 4 - Lease Obligations and Long-term Debt (Details Textual)	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2018	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)
Minimum [Member] \| Revolving Credit Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate				0.825%
Minimum [Member]
Debt Instrument, Interest Rate, Stated Percentage	1.60%			1.60%
Maximum [Member] \| Revolving Credit Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate				1.45%
Maximum [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.60%			3.60%
Lease Residual Value Guarantees [Member]
Other Commitment	$ 62,000,000			$ 62,000,000
Other Commitment, Due in Next Twelve Months	$ 0			0
Tractors [Member]
Number of Capital Leased Units Converted to Operating Leased Units		530
Trailers [Member] \| Scenario, Forecast [Member]
Sale Leaseback Transaction, Number of Leased Units			2,700
Trailers [Member]
Sale Leaseback Transaction, Number of Units	4,700
Conversion of Capital Leases to Operating Leases [Member]
Debt Instrument, Increase (Decrease), Other, Net		$ (61,200,000)
Operating Leases, Future Minimum Payments Due	$ 21,900,000			21,900,000
Sale Leaseback of Trailers [Member]
Debt Instrument, Increase (Decrease), Other, Net	(69,200,000)
Operating Leases, Future Minimum Payments Due	5,700,000			5,700,000
Revenue Equipment Installment Notes [Member]
Other Long-term Debt	$ 700,000			$ 700,000
Long-term Debt, Weighted Average Interest Rate	6.20%			6.20%
Revolving Credit Facility [Member]
Debt Instrument, Term				5 years
Line of Credit Facility, Maximum Borrowing Capacity	$ 300,000,000			$ 300,000,000
Long-term Line of Credit	151,400,000			151,400,000	$ 132,400,000
Letters of Credit Outstanding, Amount	3,200,000			3,200,000	1,700,000
Operating Leases, Future Minimum Payments Due	74,906,000			74,906,000
Sale Leaseback Transaction, Deferred Gain, Net	$ 1,200,000			1,200,000
Sale Leaseback Transaction, Term of Contract	1 year
Other Long-term Debt	$ 700,000			700,000	1,800,000
Other Long-term Debt, Current	0			0	$ 948,000
Letters of Credit Outstanding, Amount	$ 3,200,000			$ 3,200,000