RESTRICTED CASH AND INVESTMENTS - Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Dec. 29, 2019	Dec. 30, 2018
Less than 12 months
Estimated fair value	$ 15,920	$ 36,743
Unrealized losses	(32)	(362)
12 months or more
Estimated fair value	3,041	68,476
Unrealized losses	(4)	(1,106)
Estimated fair value	18,961	105,219
Unrealized losses	(36)	(1,468)
Municipal debt securities
Less than 12 months
Estimated fair value	0	12,803
Unrealized losses	0	(74)
12 months or more
Estimated fair value	0	22,638
Unrealized losses	0	(442)
Estimated fair value	0	35,441
Unrealized losses	0	(516)
Corporate debt securities
Less than 12 months
Estimated fair value	15,920	22,567
Unrealized losses	(32)	(277)
12 months or more
Estimated fair value	2,765	44,463
Unrealized losses	(2)	(631)
Estimated fair value	18,685	67,030
Unrealized losses	(34)	(908)
Agency mortgage-backed securities
Less than 12 months
Estimated fair value	0	385
Unrealized losses	0	0
12 months or more
Estimated fair value	276	1,375
Unrealized losses	(2)	(33)
Estimated fair value	276	1,760
Unrealized losses	(2)	(33)
U.S. government and agency securities
Less than 12 months
Estimated fair value	0	988
Unrealized losses	0	(11)
12 months or more
Estimated fair value	0	0
Unrealized losses	0	0
Estimated fair value	0	988
Unrealized losses	$ 0	$ (11)

Debt securities, 12 months or more [Abstract]

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Debt securities, Less than 12 months [Abstract]

+ References

No definition available.

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- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for less than 12 months.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer.

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