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

No definition available.

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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.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

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- Definition

Term of lessee's finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Paragraph 1
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- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

The accrued insurance premium payable to third-party financing companies.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The percentage of borrowing availability of the maximum revolver amount.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
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- Definition

Represents the borrowing base of a credit facility before any additions pertaining to eligible revenue equipment.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the percentage of eligible investment grade accounts receivable elements for calculating the maximum amount of the credit facility.

+ References

No definition available.

+ Details

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- Definition

Represents the percentage of eligible revenue equipment elements for calculating the maximum amount of the credit facility.

+ References

No definition available.

+ Details

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- Definition

Represents the percentage of eligible unbilled accounts receivable elements for calculating the maximum amount of the credit facility.

+ References

No definition available.

+ Details

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- Definition

Represents the percentage of newly acquired revenue equipment elements for calculating the maximum amount of the credit facility.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
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- Definition

Description of consolidated fixed charge coverage and achievement of certain financial ratios.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
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- Definition

Percentage of original cost at which the Company has the option to purchase at the end of the lease.

+ References

No definition available.

+ Details

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Namespace Prefix:	usak_
Data Type:	num:percentItemType
Balance Type:	na
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- Definition

The initial monthly payment in a sale-leaseback transaction.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The amount of increase decrease in long-term debt borrowing capacity.

+ References

No definition available.

+ Details

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Balance Type:	credit
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- Definition

Represents information about the additional borrowing capacity amount.

+ References

No definition available.

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- Definition

The amount of the maximum increase available that is subject to lender approval.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The minimum excess availability requirement as a percentage of the maximum revolver amount.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
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- Definition

The proceeds from obligation under finance lease.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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DEBT - Other (Details) - USD ($)			1 Months Ended		9 Months Ended
DEBT - Other (Details) - USD ($)	Jan. 31, 2019	Feb. 15, 2015	Jul. 31, 2019	Apr. 30, 2019	Sep. 30, 2019	Oct. 31, 2020	Sep. 30, 2020	Apr. 20, 2020	Dec. 31, 2019	Oct. 31, 2019
Debt Instruments
Long-term debt							$ 90,898,000		$ 89,514,000
Borrowing based threshold for eligible unbilled accounts receivable (as a percent)	85.00%
Remaining borrowing capacity							$ 47,600,000
Weighted average interest rate							2.27%
Proceeds from obligation under finance lease			$ 2,300,000		$ 12,795,000
Finance lease contract term			5 years
Initial monthly payment in sale-leaseback transaction			$ 30,000.00
Tractors
Debt Instruments
Proceeds from obligation under finance lease				$ 10,500,000
Finance lease contract term				5 years
Initial monthly payment in sale-leaseback transaction				$ 100,000
Percentage of original cost at which Company has option to purchase at end of lease				32.50%
Obligations Under Finance Lease
Debt Instruments
Long-term debt							$ 10,323,000		11,783,000
Revolving Credit Facility
Debt Instruments
Long-term debt	$ 225,000,000.0	$ 170,000,000.0					80,575,000	$ 170,000,000.0	73,225,000
Maximum increase available subject to lender approval	75,000,000.0
Excercisable, incremental borrowing capacity	$ 20,000,000.0
Term of debt instrument	5 years	5 years
Increase (decrease) in borrowing capacity								$ (55,000,000.0)
Fixed charge coverage ratio	1.0
Commitment fee percentage	0.25%
Borrowing base before additions of eligible revenue equipment	$ 10,000,000.0
Newly acquired revenue equipment (as a percent)	85.00%
Eligible revenue equipment (as a percent)	85.00%
Percentage of maximum revolver amount	10.00%
Minimum excess availability percentage of maximum revolver amount	20.00%
Letter of credit outstanding							7,900,000
Revolving Credit Facility \| Minimum
Debt Instruments
Borrowing based threshold eligible investment grade accounts receivable (as a percent)	85.00%
Revolving Credit Facility \| Maximum
Debt Instruments
Borrowing based threshold eligible investment grade accounts receivable (as a percent)	90.00%
Swingline sub-facility
Debt Instruments
Long-term debt	$ 25,000,000.0						$ 0
Letter of credit sub-facility
Debt Instruments
Long-term debt	$ 15,000,000.0
Base Rate \| Revolving Credit Facility \| Minimum
Debt Instruments
Basis spread on variable rate (as a percent)	0.25%
Base Rate \| Revolving Credit Facility \| Maximum
Debt Instruments
Basis spread on variable rate (as a percent)	0.75%
London Interbank Offered Rate (LIBOR) \| Revolving Credit Facility \| Minimum
Debt Instruments
Basis spread on variable rate (as a percent)	1.25%
London Interbank Offered Rate (LIBOR) \| Revolving Credit Facility \| Maximum
Debt Instruments
Basis spread on variable rate (as a percent)	1.75%
Insurance Premiums Financing Note
Debt Instruments
Long-term debt									$ 4,506,000
Accrued Premium Insurance Payable						$ 5,100,000				$ 4,500,000