Marketable Securities - Schedule of Gross Unrealized Losses and Fair Value by Major Security Type (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	$ (6,852)	$ (2,974)
Fair Value Less than 12 Consecutive Months	260,449	352,211
Gross Unrealized Losses 12 Consecutive Months or Longer	(1,932)	(4,249)
Fair Value 12 Consecutive Months or Longer	25,354	252,298
Gross Unrealized Losses, Total	(8,784)	(7,223)
Fair Value, Total	285,803	604,509
U.S. Treasury securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses 12 Consecutive Months or Longer		(30)
Fair Value 12 Consecutive Months or Longer		13,087
Gross Unrealized Losses, Total		(30)
Fair Value, Total		13,087
Agency securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months		(16)
Fair Value Less than 12 Consecutive Months		20,808
Gross Unrealized Losses 12 Consecutive Months or Longer		(11)
Fair Value 12 Consecutive Months or Longer		20,812
Gross Unrealized Losses, Total		(27)
Fair Value, Total		41,620
Mortgage-backed securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(2,604)	(745)
Fair Value Less than 12 Consecutive Months	117,813	79,007
Gross Unrealized Losses 12 Consecutive Months or Longer	(125)	(1,740)
Fair Value 12 Consecutive Months or Longer	3,078	86,392
Gross Unrealized Losses, Total	(2,729)	(2,485)
Fair Value, Total	120,891	165,399
Corporate securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(777)	(1,585)
Fair Value Less than 12 Consecutive Months	69,985	183,691
Gross Unrealized Losses 12 Consecutive Months or Longer	(1,101)	(2,161)
Fair Value 12 Consecutive Months or Longer	18,432	100,926
Gross Unrealized Losses, Total	(1,878)	(3,746)
Fair Value, Total	88,417	284,617
Municipal securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(88)	(218)
Fair Value Less than 12 Consecutive Months	21,417	34,165
Gross Unrealized Losses 12 Consecutive Months or Longer		(17)
Fair Value 12 Consecutive Months or Longer		9,522
Gross Unrealized Losses, Total	(88)	(235)
Fair Value, Total	21,417	43,687
Other [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(3,383)	(410)
Fair Value Less than 12 Consecutive Months	51,234	34,540
Gross Unrealized Losses 12 Consecutive Months or Longer	(706)	(290)
Fair Value 12 Consecutive Months or Longer	3,844	21,559
Gross Unrealized Losses, Total	(4,089)	(700)
Fair Value, Total	$ 55,078	$ 56,099