SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 25, 2020	Mar. 27, 2019
Cash paid for:
Income taxes, net of refunds	$ 801	$ 617
Interest, net of amounts capitalized	61	72
Non-cash investing activities:
Accrued purchases of property and equipment	13,715	15,763
Capitalized equity-based compensation	13	27
Non-cash financing activities:
Establishment of liabilities under tax receivable agreement	310	1,636
Redemption or Exchange of Units | Class A Common Stock
Non-cash financing activities:
Class A common stock issued in connection with the redemption of LLC Interests	0	1
Redemption or Exchange of Units | Class B Common Stock
Non-cash financing activities:
Cancellation of Class B common stock in connection with the redemption of LLC Interests	$ 0	$ (1)