FAIR VALUE MEASUREMENT (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 30, 2018 | Jul. 01, 2018 | Dec. 31, 2017 |
Fair Value Measurement [Line Items] | | | | |
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents | $ 71,868 | $ 102,450 | $ 81,990 | $ 73,831 |
Restricted investments classified as held-to-maturity | 148,154 | 155,641 | | |
Deferred compensation mutual funds | 28,416 | 23,363 | | |
Municipal debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 76,084 | 76,690 | | |
Corporate debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 69,081 | 75,432 | | |
Agency mortgage-backed securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 1,944 | 2,531 | | |
U.S. government and agency securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 1,045 | 988 | | |
Total Fair Value | | | | |
Fair Value Measurement [Line Items] | | | | |
Cash and cash equivalents | 23,124 | 46,988 | | |
Total Fair Value | Restricted Assets | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted cash and cash equivalents | 48,744 | 55,462 | | |
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents | 71,868 | 102,450 | | |
Restricted investments classified as held-to-maturity | 148,154 | 155,641 | | |
Deferred compensation mutual funds | 28,416 | 23,363 | | |
Total Fair Value | Restricted Assets | Municipal debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 76,084 | 76,690 | | |
Total Fair Value | Restricted Assets | Corporate debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 69,081 | 75,432 | | |
Total Fair Value | Restricted Assets | Agency mortgage-backed securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 1,944 | 2,531 | | |
Total Fair Value | Restricted Assets | U.S. government and agency securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 1,045 | 988 | | |
Quoted Prices in Active Markets for Identical Assets (Level 1) | | | | |
Fair Value Measurement [Line Items] | | | | |
Cash and cash equivalents | 23,124 | 46,988 | | |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Restricted Assets | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted cash and cash equivalents | 48,744 | 55,462 | | |
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents | 71,868 | 102,450 | | |
Restricted investments classified as held-to-maturity | 0 | 0 | | |
Deferred compensation mutual funds | 28,416 | 23,363 | | |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Restricted Assets | Municipal debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 0 | 0 | | |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Restricted Assets | Corporate debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 0 | 0 | | |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Restricted Assets | Agency mortgage-backed securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 0 | 0 | | |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Restricted Assets | U.S. government and agency securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 0 | 0 | | |
Significant Other Observable Inputs (Level 2) | | | | |
Fair Value Measurement [Line Items] | | | | |
Cash and cash equivalents | 0 | 0 | | |
Significant Other Observable Inputs (Level 2) | Restricted Assets | | | | |
Fair Value Measurement [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 | 148,154 | 155,641 | | |
Deferred compensation mutual funds | 0 | 0 | | |
Significant Other Observable Inputs (Level 2) | Restricted Assets | Municipal debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 76,084 | 76,690 | | |
Significant Other Observable Inputs (Level 2) | Restricted Assets | Corporate debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 69,081 | 75,432 | | |
Significant Other Observable Inputs (Level 2) | Restricted Assets | Agency mortgage-backed securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 1,944 | 2,531 | | |
Significant Other Observable Inputs (Level 2) | Restricted Assets | U.S. government and agency securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 1,045 | 988 | | |
Significant Unobservable Inputs (Level 3) | | | | |
Fair Value Measurement [Line Items] | | | | |
Cash and cash equivalents | 0 | 0 | | |
Significant Unobservable Inputs (Level 3) | Restricted Assets | | | | |
Fair Value Measurement [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 | | |
Deferred compensation mutual funds | 0 | 0 | | |
Significant Unobservable Inputs (Level 3) | Restricted Assets | Municipal debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 0 | 0 | | |
Significant Unobservable Inputs (Level 3) | Restricted Assets | Corporate debt securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 0 | 0 | | |
Significant Unobservable Inputs (Level 3) | Restricted Assets | Agency mortgage-backed securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | 0 | 0 | | |
Significant Unobservable Inputs (Level 3) | Restricted Assets | U.S. government and agency securities | | | | |
Fair Value Measurement [Line Items] | | | | |
Restricted investments classified as held-to-maturity | $ 0 | $ 0 | | |