CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 25, 2020	Mar. 27, 2019
OPERATING ACTIVITIES
Net income (loss) (including amounts attributable to non-controlling interests)	$ (1,079)	$ 3,607
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation expense	11,768	8,966
Capitalized Computer Software, Amortization	260	0
Non-cash operating lease cost	$ 10,742	$ 8,911
Noncontrolling Interest, Weighted Average Ownership Percentage	8.40%	20.30%
Equity-based compensation	$ 1,300	$ 1,692
Deferred income taxes	3,775	95
Non-cash interest expense	69	0
(Gain) loss on sale of marketable securities	(79)	0
Impairment and loss on disposal of assets	2,088	351
Unrealized (gain) loss on available-for-sale securities	356	(157)
Other non-cash expense (income)	183	2
Changes in operating assets and liabilities:
Accounts receivable	3,150	5,976
Inventories	306	123
Prepaid expenses and other current assets	(439)	(474)
Other assets	(1,039)	(2,335)
Accounts payable	(4,449)	(61)
Accrued expenses	(6,330)	880
Accrued wages and related liabilities	(5,113)	(3,025)
Other current liabilities	273	963
Long-term operating lease liabilities	(8,755)	(8,324)
Other long-term liabilities	497	9
NET CASH PROVIDED BY OPERATING ACTIVITIES	7,484	17,199
INVESTING ACTIVITIES
Purchases of property and equipment	(19,159)	(24,985)
Purchases of marketable securities	(192)	(389)
Sales of marketable securities	20,000	15,000
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	649	(10,374)
FINANCING ACTIVITIES
Proceeds from revolving credit facility	50,000	0
Payments on principal of finance leases	(615)	(339)
Distributions paid to non-controlling interest holders	(305)	(109)
Payments under tax receivable agreement	(6,569)	(707)
Proceeds from stock option exercises	1,032	1,452
Payment, Tax Withholding, Share-based Payment Arrangement	(969)	25
NET CASH PROVIDED BY FINANCING ACTIVITIES	42,574	322
NET INCREASE IN CASH AND CASH EQUIVALENTS	50,707	7,147
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	37,099	24,750
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 87,806	$ 31,897