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Significant Accounting Policies (Narrative) (Details) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 29, 2018 USD ($) | Mar. 30, 2019 USD ($) state segment property store item | Mar. 31, 2018 USD ($)
Significant Accounting Policies [Line Items] |  |  |
Company operated stores | store |  | 1,197 |
Franchised locations | store |  | 98 |
Number of wholesale locations | property |  | 8 |
Number of retread facilities | property |  | 3 |
Dealer-operated automotive repair centers | store |  | 2 |
Number of States in which Entity Operates | state |  | 28 |
Number of operating segments | segment |  | 1 |
Number of reporting units | item |  | 1 |
Advertising expenses amortization period |  | 2 months |
Impairment of intangible assets | $ 0 |  |
Property Lease Guarantee [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Maximum potential guarantee payments |  | $ 1,800,000 |
Liability for anticipated lease defaults |  | $ 0 | $ 200,000
Stock Options [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Options award vesting period |  | 4 years |
Senior Management [Member] | Restricted Stock [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Options award vesting period |  | 3 years |
Maximum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Adoption of new accounting principle |  | $ 190,000,000 |
Maximum [Member] | Stock Options [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Options award vesting period |  | 4 years |
Maximum [Member] | Restricted Stock [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Options award vesting period |  | 4 years |
Minimum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Adoption of new accounting principle |  | $ 165,000,000 |
Minimum [Member] | Stock Options [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Options award vesting period |  | 3 years |
Minimum [Member] | Restricted Stock [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Options award vesting period |  | 3 years |
Buildings and Improvements [Member] | Maximum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Useful lives |  | 39 years |
Buildings and Improvements [Member] | Minimum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Useful lives |  | 10 years |
Machinery, Fixtures And Equipment [Member] | Maximum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Useful lives |  | 15 years |
Machinery, Fixtures And Equipment [Member] | Minimum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Useful lives |  | 3 years |
Vehicles [Member] | Maximum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Useful lives |  | 10 years |
Vehicles [Member] | Minimum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Useful lives |  | 5 years |
Computer Hardware And Software [Member] | Maximum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Useful lives |  | 7 years |
Computer Hardware And Software [Member] | Minimum [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Useful lives |  | 3 years |

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