Available for Sale Debt Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 28, 2019	Dec. 29, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 5,939,950	$ 3,944,459
Unrealized Gain	133,662	2,441
Unrealized Loss	1,573	68,190
Fair Value	6,072,039	3,878,710
Tax exempt bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	767,931	1,256,673
Unrealized Gain	3,429	184
Unrealized Loss	130	12,759
Fair Value	771,230	1,244,098
Taxable Bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,002,036	2,527,468
Unrealized Gain	120,132	1,737
Unrealized Loss	1,443	55,085
Fair Value	5,120,725	2,474,120
Restricted Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	169,983	160,318
Unrealized Gain	10,101	520
Unrealized Loss	0	346
Fair Value	$ 180,084	$ 160,492

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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