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v2.4.1.9

Stock-Based Compensation (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 0 Months Ended
--- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total payments for employees' tax obligations | $ 2.6 us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation | $ 0 us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation |
PSUs |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Percent of target shares earned |  |  | 200.00%fss_PercentageOfTargetShares / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember
Shares withheld to satisfy tax withholding obligation | 0.2 us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |  |
Total payments for employees' tax obligations | $ 2.6 us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember |  |

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- Definition Percentage Of Target Shares + References No definition available. + Details
Name: | fss_PercentageOfTargetShares
Namespace Prefix: | fss_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

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- Definition For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer. + References No definition available. + Details
Name: | us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |