CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 26, 2021	Mar. 27, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020	Dec. 26, 2020
Statement of Cash Flows [Abstract]
Net income (loss)	$ 35,168	$ (19,932)	$ 3,091	$ 15,235	$ (856)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	26,423		8,636	50,275	16,435
Non-cash lease cost				37,938	17,412
Gain on foreign denominated transactions				5,707	2,285
Loss on derivatives not designed as hedges				(425)	0
Bad debt expense				1,739	4,351
Asset impairment charges	2,178		3,499	3,431	6,411
Amortization of deferred financing costs and bond discounts				3,619	2,573
Benefit (provision) for deferred income taxes				4,742	(1,471)
Loss on debt extinguishment	78		0	45,576	0
Other, net				1,375	1,365
Changes in assets and liabilities:
Accounts and notes receivable, net				(24,174)	(26,134)
Inventory				(396)	(577)
Prepaid and other assets				(20,885)	(9,665)
Advertising fund assets and liabilities, restricted				12,548	3,835
Deferred commissions				(809)	(1,614)
Deferred revenue				2,994	(2,780)
Accounts payable				3,860	11,696
Accrued expenses and other liabilities				9,707	349
Income tax receivable				3,665	4,051
Operating lease liabilities				(31,034)	(14,109)
Cash provided by operating activities				124,688	13,557
Cash flows from investing activities:
Capital expenditures				(46,222)	(24,920)
Cash used in business acquisitions, net of cash acquired				(205,556)	(28,490)
Proceeds from sale-leaseback transactions				49,166	0
Proceeds from sale of company-operated stores				5,775	0
Cash used in investing activities				(196,837)	(53,410)
Cash flows from financing activities:
Payment of contingent consideration related to acquisitions				0	(1,783)
Payment of debt extinguishment and issuance costs				(2,408)	(2,421)
Repayment of long-term debt				(712,649)	(12,809)
Proceeds from revolving lines of credit and short-term debt				213,800	79,501
Repayments of revolving lines of credit and short-term debt				(152,800)	0
Repayment of principal portion of finance lease liability				(1,127)	(117)
Proceeds from initial public offering, net of underwriting discounts				661,500	0
Net proceeds from underwriters' exercise of over-allotment option				99,225	0
Repurchases of common stock				(43,040)	0
Payment for termination of interest rate swaps				(21,826)	0
Other, net				152	0
Cash provided by financing activities				40,827	62,371
Effect of exchange rate changes on cash				1,813	(337)
Net change in cash, cash equivalents, restricted cash, and cash included in advertising fund assets, restricted				(29,509)	22,181
Cash and cash equivalents, beginning of period		172,611		172,611	34,935	$ 34,935
Cash included in advertising fund assets, restricted, beginning of period	30,882		12,590	30,882	12,590	19,369
Restricted cash, beginning of period		15,827		15,827	0	0
Cash, cash equivalents, restricted cash, and cash included in advertising fund assets, restricted, beginning of period		$ 207,807		207,807	58,026	58,026
Cash and cash equivalents, end of period	147,257		67,617	147,257	67,617	172,611
Cash included in advertising fund assets, restricted, end of period	30,882		12,590	30,882	12,590	19,369
Restricted cash, end of period	159		0	159	0	15,827
Cash, cash equivalents, restricted cash, and cash included in advertising fund assets, restricted, end of period	178,298		80,207	$ 178,298	$ 80,207	$ 207,807
Supplemental cash flow disclosures - non-cash items:
Accrued capital expenditures	5,772		2,434
Supplemental cash flow disclosures - cash paid for:
Interest	38,966		32,517
Income taxes	$ 5,531		$ 649