Description Of Business, Basis Of Presentation And Summary Of Significant Accounting Policies (Narrative) (Details)	3 Months Ended	12 Months Ended
	Mar. 28, 2020 USD ($) property store state	Mar. 28, 2020 USD ($) property store state segment item	Mar. 30, 2019 USD ($)	Mar. 31, 2018 USD ($)
Significant Accounting Policies [Line Items]
Company operated stores | store	1,283	1,283
Franchised locations | property	98	98
Number of wholesale locations | property	8	8
Number of retread facilities | property	3	3
Dealer-operated automotive repair centers | property	2	2
Number of States in which Entity Operates | state	32	32
Number of operating segments | segment		1
Total assets	$ 2,049,457,000	$ 2,049,457,000	$ 1,312,288,000
Total liabilities	1,315,017,000	1,315,017,000	612,778,000
Operating lease right-of-use assets	199,729,000	199,729,000
Operating lease obligations	201,135,000	201,135,000
Finance lease asset	196,575,000	196,575,000	128,029,000
Finance lease liability	$ 330,630,000	330,630,000
Barter credits		7,700,000	5,400,000
Number of stores expected to close | store	36
Impairment of long-lived assets		6,579,000	0	$ 0
Impairment of long-lived assets, related to store closures		$ 4,300,000
Number of reporting units | item		1
Impairment of intangible assets		$ 0	0	$ 0
Advertising expenses amortization period		2 months
Adoption of new accounting principle			(582,000)
Operating Lease ROU Assets [Member]
Significant Accounting Policies [Line Items]
Impairment of long-lived assets		$ 4,400,000
Finance Lease ROU Assets [Member]
Significant Accounting Policies [Line Items]
Impairment of long-lived assets		600,000
Leasehold Improvements And Equipment [Member]
Significant Accounting Policies [Line Items]
Impairment of long-lived assets		$ 1,600,000
Accounting Standards Update 2016-02 [Member]
Significant Accounting Policies [Line Items]
Total assets			165,300,000
Total liabilities			165,900,000
Operating lease right-of-use assets			186,900,000
Operating lease obligations			174,400,000
Finance lease asset			700,000
Operating lease, asset (liability), difference in assets resulting from favorable leases			19,600,000
Operating lease, asset (liability), difference in assets resulting from unfavorable lease intangibles and deferred rent			7,200,000
Assets related to finance lease construction			11,100,000
Lease financial obligations			18,600,000
Adoption of new accounting principle			(600,000)
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] | 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] | 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
Leased Stores [Member] | Accounting Standards Update 2016-02 [Member]
Significant Accounting Policies [Line Items]
Finance lease asset			8,400,000
Finance lease liability			$ 16,600,000