v2.4.1.9

Segment and Significant Customer Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 operating_segment reportable_segment business_activity Segment_Managers	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Business activity (in business activities)	1ftnt_NumberOfBusinessActivities
Segment managers responsible for operations (in segment managers)	0ftnt_NumberOfSegmentManagersResponsibleForOperations
Number of operating segments (in operating segments)	1us-gaap_NumberOfOperatingSegments
Number of reportable segments (in reportable segments)	1us-gaap_NumberOfReportableSegments
Revenue	$ 212,886us-gaap_SalesRevenueNet	$ 168,949us-gaap_SalesRevenueNet
Property and equipment - net	63,487us-gaap_PropertyPlantAndEquipmentNet		58,919us-gaap_PropertyPlantAndEquipmentNet
Americas [Member]
Segment Reporting Information [Line Items]
Revenue	91,560us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = us-gaap_AmericasMember	72,432us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = us-gaap_AmericasMember
Property and equipment - net	56,751us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = us-gaap_AmericasMember		53,045us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = us-gaap_AmericasMember
United States
Segment Reporting Information [Line Items]
Revenue	58,501us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_US	44,793us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_US
Property and equipment - net	49,471us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US		46,116us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US
Canada [Member]
Segment Reporting Information [Line Items]
Property and equipment - net	6,356us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = ftnt_CanadaMember		6,054us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = ftnt_CanadaMember
Other Americas [Member]
Segment Reporting Information [Line Items]
Revenue	33,059us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = ftnt_OtherAmericasMember	27,639us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = ftnt_OtherAmericasMember
Property and equipment - net	924us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = ftnt_OtherAmericasMember		875us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = ftnt_OtherAmericasMember
EMEA [Member]
Segment Reporting Information [Line Items]
Revenue	75,664us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = ftnt_EuropeMiddleEastAndAfricaMember	56,643us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = ftnt_EuropeMiddleEastAndAfricaMember
Property and equipment - net	3,723us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = ftnt_EuropeMiddleEastAndAfricaMember		3,256us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = ftnt_EuropeMiddleEastAndAfricaMember
APAC [Member]
Segment Reporting Information [Line Items]
Revenue	45,662us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = ftnt_AsiaPacificAndJapanMember	39,874us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = ftnt_AsiaPacificAndJapanMember
Property and equipment - net	$ 3,013us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = ftnt_AsiaPacificAndJapanMember		$ 2,618us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = ftnt_AsiaPacificAndJapanMember

X

- Definition

Number of business activities

+ References

No definition available.

+ Details

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Namespace Prefix:	ftnt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of Segment Managers Responsible for Operations

+ References

No definition available.

+ Details

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Namespace Prefix:	ftnt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Period Type:	duration

X

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 13

-Subparagraph a

-Article 5



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 8

-Article 7

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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- Details

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X

- Details

Name:	us-gaap_StatementGeographicalAxis=ftnt_AsiaPacificAndJapanMember
Namespace Prefix:
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Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementGeographicalAxis=ftnt_CanadaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementGeographicalAxis=ftnt_EuropeMiddleEastAndAfricaMember
Namespace Prefix:
Data Type:	na
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X

- Details

Name:	us-gaap_StatementGeographicalAxis=ftnt_OtherAmericasMember
Namespace Prefix:
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- Details

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