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.

+ Details

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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.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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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Balance Type:	credit
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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

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

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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
-Section 50
-Paragraph 4
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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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Namespace Prefix:	usak_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The percentage of borrowing availability of the maximum revolver amount.

+ References

No definition available.

+ Details

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Namespace Prefix:	usak_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	usak_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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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Namespace Prefix:	usak_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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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Namespace Prefix:	usak_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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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Namespace Prefix:	usak_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	usak_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents information about the additional borrowing capacity amount.

+ References

No definition available.

+ Details

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Namespace Prefix:	usak_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	usak_
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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Namespace Prefix:	usak_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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- Details

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Name:	us-gaap_CreditFacilityAxis=usak_SwingLineSubFacilityMember
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Name:	us-gaap_DebtInstrumentAxis=usak_OvernightBorrowingsMember
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- Details

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Balance Type:
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LONG-TERM DEBT (Details) - USD ($)	Jan. 31, 2019	Feb. 15, 2015	Dec. 31, 2019	Oct. 31, 2019	Dec. 31, 2018	Oct. 31, 2018
Debt Instruments
Long-term debt			$ 89,514,000		$ 89,735,000
Remaining borrowing capacity			55,100,000
Weighted average interest rate					3.57%
Obligation under finance lease
Debt Instruments
Long-term debt			11,783,000
Credit Facility
Debt Instruments
Long-term debt	$ 225,000,000.0	$ 170,000,000.0	73,225,000		$ 85,300,000
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
Fixed charge coverage ratio	1.0
Commitment fee percentage	0.25%
Borrowing based threshold, eligible noninvestment grade accounts (as a percent)	85.00%
Borrowing based threshold for eligible unbilled accounts receivable (as a percent)	85.00%
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			7,400,000
Credit Facility \| Minimum
Debt Instruments
Borrowing based threshold eligible investment grade accounts receivable (as a percent)	85.00%
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
Swingline sub-facility \| Overnight Borrowings
Debt Instruments
Long-term line of credit			0
Letter of credit sub-facility
Debt Instruments
Long-term debt	$ 15,000,000.0
Base Rate \| Credit Facility \| Minimum
Debt Instruments
Basis spread on variable rate (as a percent)	0.25%
Base Rate \| Credit Facility \| Maximum
Debt Instruments
Basis spread on variable rate (as a percent)	0.75%
London Interbank Offered Rate (LIBOR) \| Credit Facility \| Minimum
Debt Instruments
Basis spread on variable rate (as a percent)	1.25%
London Interbank Offered Rate (LIBOR) \| 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		$ 4,435,000
Accrued Premium Insurance Payable				$ 4,500,000		$ 4,700,000