Commitments and Contingencies - Charge-backs for Various Contracts (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2018	$ 27,352
2019	16,113
2020	6,382
2021	2,183
2022	673
Thereafter	41
Total	$ 52,744

- Definition

Amount of estimated contractual obligations to be paid in the next fiscal year following the latest fiscal year related to the cancellation of various contracts.

+ References

No definition available.

+ Details

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Namespace Prefix:	lad_
Data Type:	xbrli:monetaryItemType
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- Definition

Amount of estimated contractual obligations to be paid in the fifth fiscal year following the latest fiscal year related to the cancellation of various contracts

+ References

No definition available.

+ Details

Name:	lad_ChargeBacksFutureMinimumPaymentsDueInFiveYears
Namespace Prefix:	lad_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of estimated contractual obligations to be paid in the fourth fiscal year following the latest fiscal year related to the cancellation of various contracts

+ References

No definition available.

+ Details

Name:	lad_ChargeBacksFutureMinimumPaymentsDueInFourYears
Namespace Prefix:	lad_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of estimated contractual obligations to be paid in the third fiscal year following the latest fiscal year related to the cancellation of various contracts.

+ References

No definition available.

+ Details

Name:	lad_ChargeBacksFutureMinimumPaymentsDueInThreeYears
Namespace Prefix:	lad_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of estimated contractual obligations to be paid in the second fiscal year following the latest fiscal year related to the cancellation of various contracts.

+ References

No definition available.

+ Details

Name:	lad_ChargeBacksFutureMinimumPaymentsDueInTwoYears
Namespace Prefix:	lad_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of estimated contractual obligations to be paid after the fifth fiscal year following the latest fiscal year related to the cancellation of various contracts.

+ References

No definition available.

+ Details

Name:	lad_ChargeBacksFutureMinimumPaymentsDueThereafter
Namespace Prefix:	lad_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of liabilities pertaining to charge backs.

+ References

No definition available.

+ Details

Name:	lad_ChargeBacksLiabilities
Namespace Prefix:	lad_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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