v2.4.0.8

Marketable Securities (Additional information) (Details) (USD $)
In Thousands, unless otherwise specified

6 Months Ended

12 Months Ended

Jun. 28, 2014

Dec. 28, 2013

Gross Unrealized Losses-OTTI

$ (21,739)

^[1]

$ (57,356)

^[1]

Change In Treasury Bond Yield Description

The decline was due to increases in the 10 Year Treasury Bond Yield during 2013, which caused market valuations of securities in our investment portfolios to decline.

Held To Maturity Securities Continuous Unrealized Loss Position Percentage

43.00%

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total

999,832

1,153,765

Available For Sale Securities Continuous Unrealized Loss Position Amortization Cost

1,026,696

1,215,498

Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments

$ 5,125

^[2]

$ 4,377

^[2]

[1]	Represents impairment not related to credit for those investment securities that have been determined to be other-than-temporarily impaired.
[2]	Represents unrealized losses on investment securities that have not been determined to be other-than-temporarily impaired.

X

- Definition

This item represents the aggregate amortization cost of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities

+ References

No definition available.

+ Details

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X

- Definition

Represent the total details of The majority of the decline due to an unusually change and causing market valuations of many securities.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
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X

- Definition

This item represents the percentage of securities categorized as held-to-maturity which are in an unrealized loss position.

+ References

No definition available.

+ Details

Name:	grmn_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionPercentage
Namespace Prefix:	grmn_
Data Type:	num:percentItemType
Balance Type:	na
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X

- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities and excluding other than temporary impairments (OTTI), if any, recognized elsewhere.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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X

- Definition

Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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