The limit amount of the loan that can be used for working capital purposes.

No definition available.

Name:	rusha_DebtInstrumentLoanLimitAmountForWorkingCapitalPurposes
Namespace Prefix:	rusha_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of loan limit that can be used to purchase used inventory.

+ References

No definition available.

+ Details

Name:	rusha_DebtInstrumentLoanLimitAmountToPurchaseUsedInventory
Namespace Prefix:	rusha_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amounts borrowed to finance the purchase of new and used commercial vehicle inventory.

+ References

No definition available.

+ Details

Name:	rusha_FloorPlanNotesPayable
Namespace Prefix:	rusha_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12069-110248

+ Details

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

- Definition

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
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

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=rusha_RushTruckCentresOfCanadaLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_FinancialGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=rusha_BMOHarrisBankNAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=rusha_FloorPlanCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 14 - Subsequent Events (Details Textual) $ in Thousands, $ in Millions		12 Months Ended
	Apr. 25, 2019 USD ($)	Dec. 31, 2018 USD ($)	Apr. 25, 2019 CAD ($)	Mar. 31, 2019 USD ($)	Feb. 25, 2019	Jul. 07, 2016 USD ($)
Floor Plan Notes Payable		$ 1,023,019		$ 1,111,473
Rush Truck Centres of Canada Limited [Member]
Equity Method Investment, Ownership Percentage					50.00%
Subsequent Event [Member] \| Financial Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 250
BMO Harris Bank N.A. [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 100,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.37%
BMO Harris Bank N.A. [Member] \| Subsequent Event [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.20%
BMO Harris Bank N.A. [Member] \| Floor Plan Credit Agreement [Member]
Line of Credit Facility, Maximum Borrowing Capacity						$ 875,000
Floor Plan Notes Payable				$ 875,000
BMO Harris Bank N.A. [Member] \| Floor Plan Credit Agreement [Member] \| Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,000,000
Debt Instrument, Interest Rate, Stated Percentage	0.00%		0.00%
Debt Instrument, Loan Limit Amount to Purchase Used Inventory	$ 150,000
Debt Instrument, Loan Limit Amount for Working Capital Purposes	$ 200,000
BMO Harris Bank N.A. [Member] \| Floor Plan Credit Agreement [Member] \| Subsequent Event [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	1.25%