Marketable Securities - Schedule of Gross Unrealized Losses and Fair Value by Major Security Type (Details) - USD ($) $ in Thousands	Mar. 29, 2025	Dec. 28, 2024
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	$ (1,774)	$ (4,993)
Fair Value Less than 12 Consecutive Months	299,173	419,246
Gross Unrealized Losses 12 Consecutive Months or Longer	(23,629)	(33,696)
Fair Value 12 Consecutive Months or Longer	853,848	931,764
Gross Unrealized Losses, Total	(25,403)	(38,689)
Fair Value, Total	1,153,021	1,351,010
Agency securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(14)	(125)
Fair Value Less than 12 Consecutive Months	20,226	24,153
Gross Unrealized Losses 12 Consecutive Months or Longer	(273)	(352)
Fair Value 12 Consecutive Months or Longer	6,727	6,647
Gross Unrealized Losses, Total	(287)	(477)
Fair Value, Total	26,953	30,800
Mortgage-backed securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(59)	(137)
Fair Value Less than 12 Consecutive Months	21,127	9,803
Gross Unrealized Losses 12 Consecutive Months or Longer	(2,803)	(4,238)
Fair Value 12 Consecutive Months or Longer	24,868	29,421
Gross Unrealized Losses, Total	(2,862)	(4,375)
Fair Value, Total	45,995	39,224
Corporate debt securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(1,624)	(4,503)
Fair Value Less than 12 Consecutive Months	238,067	350,289
Gross Unrealized Losses 12 Consecutive Months or Longer	(13,173)	(19,334)
Fair Value 12 Consecutive Months or Longer	597,821	667,176
Gross Unrealized Losses, Total	(14,797)	(23,837)
Fair Value, Total	835,888	1,017,465
Municipal securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(70)	(228)
Fair Value Less than 12 Consecutive Months	18,992	35,001
Gross Unrealized Losses 12 Consecutive Months or Longer	(7,324)	(9,679)
Fair Value 12 Consecutive Months or Longer	223,300	226,901
Gross Unrealized Losses, Total	(7,394)	(9,907)
Fair Value, Total	242,292	261,902
Other [Member]
Marketable Securities [Line Items]
Gross Unrealized Losses Less than 12 Consecutive Months	(7)	0
Fair Value Less than 12 Consecutive Months	761	0
Gross Unrealized Losses 12 Consecutive Months or Longer	(56)	(93)
Fair Value 12 Consecutive Months or Longer	1,132	1,619
Gross Unrealized Losses, Total	(63)	(93)
Fair Value, Total	$ 1,893	$ 1,619

GARMIN LTD 10-Q