v2.4.0.8

Subsequent Events (Details) (Subsequent Event [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
	Jan. 31, 2014
Subsequent Event [Member]
Subsequent Event [Line Items]
Covenant-not-to-sue	$ 20.0
Covenant Not to Sue, Term	6 years

X

- Definition

Covenant Not to Sue, Term

+ References

No definition available.

+ Details

Name:	ftnt_CovenantNottoSueTerm
Namespace Prefix:	ftnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration