| Document And Entity Information | Oct. 28, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 28, 2020 |
| Entity Registrant Name | GARMIN LTD. |
| Entity Central Index Key | 0001121788 |
| Entity Emerging Growth Company | false |
| Entity File Number | 0-31983 |
| Entity Incorporation, State or Country Code | V8 |
| Entity Tax Identification Number | 98-0229227 |
| Entity Address, Address Line One | Mühlentalstrasse 2 |
| Entity Address, City or Town | Schaffhausen |
| Entity Address, Country | CH |
| Entity Address, Postal Zip Code | 8200 |
| City Area Code | +41 52 |
| Local Phone Number | 630 1600 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Registered Shares, CHF 0.10 Per Share Par Value |
| Trading Symbol | GRMN |
| Security Exchange Name | NASDAQ |
