SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 24, 2020	Jun. 26, 2019
Cash paid for:
Income taxes, net of refunds	$ 775	$ 1,554
Interest, net of amounts capitalized	491	143
Non-cash investing activities:
Accrued purchases of property and equipment	5,405	14,072
Capitalized equity-based compensation	22	55
Non-cash financing activities:
Establishment of liabilities under tax receivable agreement	313	14,395
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)