v2.4.0.8

Summary of Significant Accounting Policies , Revenue Recognition (Details) | 12 Months Ended
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Dec. 31, 2013
Minimum [Member] |
Revenue from External Customer [Line Items] |
Revenue recognition period (in years) | 1 year
Maximum [Member] |
Revenue from External Customer [Line Items] |
Revenue recognition period (in years) | 3 years

X
- Definition Revenue Recognition Period + References No definition available. + Details
Name: | ftnt_RevenueRecognitionPeriod
Namespace Prefix: | ftnt_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration