Summary of Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation and Preparation	Basis of Presentation and Preparation—The unaudited condensed consolidated financial statements of Fortinet, Inc. and its wholly-owned subsidiaries (collectively, “we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information as well as the instructions to Form 10-Q pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements, and should be read in conjunction with our audited consolidated financial statements as of and for the year ended December 31, 2014, contained in our Annual Report on Form 10-K (“Form 10-K”) filed with the SEC on March 2, 2015. In the opinion of management, all adjustments, which includes normal recurring adjustments, considered necessary for a fair presentation have been included. All intercompany balances, transactions and cash flows have been eliminated. The results of operations for the three months ended March 31, 2015 are not necessarily indicative of the results for the full year or for any future periods. The condensed consolidated balance sheet as of December 31, 2014 is derived from the audited consolidated financial statements for the year ended December 31, 2014.
Use of Estimates	The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates.
Foreign Currency Translation and Transaction Gains and Losses	In the third quarter of 2014, we reevaluated the selected functional currency of our international subsidiaries due to the nature of our business operations and recorded the cumulative impact of the reevaluation of the functional currency in the consolidated statement of operations. Subsequently, the remeasurement of the assets and liabilities of all international subsidiaries has been recorded in the consolidated statement of operations prospectively. The impact of this reevaluation is not material for our fiscal 2014 or any of our previously issued financial statements.
Recent Accounting Pronouncement	Recent Accounting Pronouncement In May 2014, the Financial Accounting Standards Board issued Accounting Standards Update No. 2014-09—Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”) to create a single, joint revenue standard that is consistent across all industries and markets for companies that prepare their financial statements in accordance with GAAP. Under ASU 2014-09, an entity is required to recognize revenue upon the transfer of promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to receive in exchange for those goods or services. ASU 2014-09 is effective for us beginning on January 1, 2017. We are currently evaluating the impact of ASU 2014-09 on our consolidated financial statements.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2015

Basis of Presentation and Preparation—The unaudited condensed consolidated financial statements of Fortinet, Inc. and its wholly-owned subsidiaries (collectively, “we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information as well as the instructions to Form 10-Q pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements, and should be read in conjunction with our audited consolidated financial statements as of and for the year ended December 31, 2014, contained in our Annual Report on Form 10-K (“Form 10-K”) filed with the SEC on March 2, 2015. In the opinion of management, all adjustments, which includes normal recurring adjustments, considered necessary for a fair presentation have been included. All intercompany balances, transactions and cash flows have been eliminated. The results of operations for the three months ended March 31, 2015 are not necessarily indicative of the results for the full year or for any future periods. The condensed consolidated balance sheet as of December 31, 2014 is derived from the audited consolidated financial statements for the year ended December 31, 2014.

Use of Estimates

The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates.

Foreign Currency Translation and Transaction Gains and Losses

In the third quarter of 2014, we reevaluated the selected functional currency of our international subsidiaries due to the nature of our business operations and recorded the cumulative impact of the reevaluation of the functional currency in the consolidated statement of operations. Subsequently, the remeasurement of the assets and liabilities of all international subsidiaries has been recorded in the consolidated statement of operations prospectively. The impact of this reevaluation is not material for our fiscal 2014 or any of our previously issued financial statements.

Recent Accounting Pronouncement

In May 2014, the Financial Accounting Standards Board issued Accounting Standards Update No. 2014-09—Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”) to create a single, joint revenue standard that is consistent across all industries and markets for companies that prepare their financial statements in accordance with GAAP. Under ASU 2014-09, an entity is required to recognize revenue upon the transfer of promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to receive in exchange for those goods or services. ASU 2014-09 is effective for us beginning on January 1, 2017. We are currently evaluating the impact of ASU 2014-09 on our consolidated financial statements.