FAIR VALUE MEASUREMENT - Fair Value Measurement (Details) - USD ($) $ in Thousands	Jun. 25, 2023	Dec. 25, 2022	Jun. 26, 2022	Dec. 26, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents, restricted cash and restricted cash equivalents	$ 107,752	$ 135,631	$ 89,995	$ 103,185
Restricted investments classified as held-to-maturity	113,399	119,525
Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	35,989	42,431
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	71,897	76,097
Agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	4,570	48
U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	943	949
Fair value, recurring | Total fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	49,653	72,054
Fair value, recurring | Total fair value | Restricted assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash and cash equivalents	58,099	63,577
Cash, cash equivalents, restricted cash and restricted cash equivalents	107,752	135,631
Restricted investments classified as held-to-maturity	113,399	119,525
Fair value, recurring | Total fair value | Restricted assets | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	35,989	42,431
Fair value, recurring | Total fair value | Restricted assets | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	71,897	76,097
Fair value, recurring | Total fair value | Restricted assets | Agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	4,570	48
Fair value, recurring | Total fair value | Restricted assets | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	943	949
Fair value, recurring | Quoted prices in active markets for identical assets (level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	49,653	72,054
Fair value, recurring | Quoted prices in active markets for identical assets (level 1) | Restricted assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash and cash equivalents	58,099	63,577
Cash, cash equivalents, restricted cash and restricted cash equivalents	107,752	135,631
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Quoted prices in active markets for identical assets (level 1) | Restricted assets | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Quoted prices in active markets for identical assets (level 1) | Restricted assets | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Quoted prices in active markets for identical assets (level 1) | Restricted assets | Agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Quoted prices in active markets for identical assets (level 1) | Restricted assets | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Significant other observable inputs (level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Fair value, recurring | Significant other observable inputs (level 2) | Restricted assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash and cash equivalents	0	0
Cash, cash equivalents, restricted cash and restricted cash equivalents	0	0
Restricted investments classified as held-to-maturity	113,399	119,525
Fair value, recurring | Significant other observable inputs (level 2) | Restricted assets | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	35,989	42,431
Fair value, recurring | Significant other observable inputs (level 2) | Restricted assets | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	71,897	76,097
Fair value, recurring | Significant other observable inputs (level 2) | Restricted assets | Agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	4,570	48
Fair value, recurring | Significant other observable inputs (level 2) | Restricted assets | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	943	949
Fair value, recurring | Significant unobservable inputs (level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Fair value, recurring | Significant unobservable inputs (level 3) | Restricted assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash and cash equivalents	0	0
Cash, cash equivalents, restricted cash and restricted cash equivalents	0	0
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Significant unobservable inputs (level 3) | Restricted assets | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Significant unobservable inputs (level 3) | Restricted assets | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Significant unobservable inputs (level 3) | Restricted assets | Agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	0	0
Fair value, recurring | Significant unobservable inputs (level 3) | Restricted assets | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments classified as held-to-maturity	$ 0	$ 0