XML 109 R70.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Income Taxes - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Dec. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Jan. 01, 2018 | Jan. 01, 2017 | Dec. 31, 2014
Income Tax [Line Items] |  |  |  |  |  |  |
Deferred tax asset, federal net operating loss carryforwards | $ 3.0 | $ 1.1 | $ 3.0 |  |  |  |
Deferred tax asset, state net operating loss carryforwards | 6.8 | 8.3 | 6.8 |  |  |  |
Deferred tax asset, foreign net operating loss carryforwards | 9.2 | 9.1 | 9.2 |  |  |  |
Deferred tax asset, U.S. research tax credit carryforwards | 1.1 | 1.1 | 1.1 |  |  |  |
Deferred tax asset, U.S. foreign tax credits carryforwards | 1.5 | 3.0 | 1.5 |  |  |  |
Deferred tax asset, U.S. alternative minimum tax credits carryforwards | 1.0 |  | 1.0 |  |  |  |
Valuation allowance | 7.7 | 10.6 | 7.7 |  |  |  |
Total deferred tax assets | 86.2 | 64.2 | 86.2 |  |  |  |
Income taxes paid |  | 13.9 | 13.3 | $ 9.6 |  |  |
Statutory tax rate |  |  |  |  | 21.00% | 35.00% |
Unrecognized tax benefits | 1.8 | 1.9 | 1.8 | 2.2 |  |  | $ 2.0
Accrual for interest and penalties | 0.6 | 0.6 | 0.6 |  |  |  |
Unrecognized tax benefits, income tax penalties and interest accrued | 2.1 | 2.2 | 2.1 |  |  |  |
Decrease in valuation allowance | $ 2.2 |  |  |  |  |  |
Income tax expense |  | $ 0.5 | $ 17.4 | $ 34.1 |  |  |
Effective income tax rate |  | 0.80% | 30.60% | 34.10% |  |  |
Benefit associated with tax planning strategy |  |  |  | $ (4.2) |  |  |
Adjustment of deferred tax assets |  |  |  | 2.4 |  |  |
Change in enacted tax rate |  |  |  | $ 0.4 |  |  |
Tax Act transition tax, rate applied to cash |  | 15.50% |  |  |  |  |
Tax Act transition tax, rate applied to earnings in excess of cash |  | 8.00% |  |  |  |  |
Research Tax Credit Carryforward |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Deferred tax asset, tax credit carryforwards expiration year |  | 2019 |  |  |  |  |
Canada |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Decrease in valuation allowance |  |  | $ 3.5 |  |  |  |
Internal Revenue Service (IRS) |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Deferred tax asset, net operating loss carryforwards expiration year |  | 2027 |  |  |  |  |
Internal Revenue Service (IRS) | Foreign Tax Credit Carryforward |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Valuation allowance |  | $ 3.0 |  |  |  |  |
State and Local Jurisdiction |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Deferred tax asset, net operating loss carryforwards expiration year |  | 2018 |  |  |  |  |
Valuation allowance |  | $ 1.0 |  |  |  |  |
Decrease in valuation allowance |  | $ (0.8) |  |  |  |  |
Foreign Tax Authority |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Deferred tax asset, net operating loss carryforwards expiration year |  | 2025 |  |  |  |  |
Deferred tax asset, tax credit carryforwards expiration year |  | 2023 |  |  |  |  |
Valuation allowance |  | $ 1.3 |  |  |  |  |
United Kingdom |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Valuation allowance |  | 6.3 |  |  |  |  |
Decrease in valuation allowance |  |  | 1.3 |  |  |  |
Current Deferred Tax Assets [Member] |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Unrecognized tax benefits, period increase (decrease) |  | (0.3) | $ (0.3) |  |  |  |
Tax law change | Internal Revenue Service (IRS) |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Change in enacted tax rate |  | 23.0 |  |  |  |  |
Tax law change | State and Local Jurisdiction |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |
Income tax expense |  | $ 0.6 |  |  |  |  |

X
- Definition Deferred Tax Assets, Operating Loss Carryforwards, Expiration Year + References No definition available. + Details
Name: | fss_DeferredTaxAssetsOperatingLossCarryforwardsExpirationYear
Namespace Prefix: | fss_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Effective Income Tax Rate Reconciliation, Tax Planning Adjustments, Amount + References No definition available. + Details
Name: | fss_EffectiveIncomeTaxRateReconciliationTaxPlanningAdjustmentsAmount
Namespace Prefix: | fss_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Income Tax [Line Items] + References No definition available. + Details
Name: | fss_IncomeTaxLineItems
Namespace Prefix: | fss_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The corporate tax rate in effect as of a particular date in a taxing jurisdiction. + References No definition available. + Details
Name: | fss_StatutoryTaxRate
Namespace Prefix: | fss_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The tax rate applied to cash and equivalents at controlled foreign corporations for the untaxed post-1986 accumulated earnings and profits taxed under the Tax Cuts and Jobs Act of 2017. + References No definition available. + Details
Name: | fss_TaxActTransitionTaxrateappliedtocash
Namespace Prefix: | fss_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The tax rate applied to earnings in excess of cash and equivalents at controlled foreign corporations for the untaxed post-1986 accumulated earnings and profits taxed under the Tax Cuts and Jobs Act of 2017. + References No definition available. + Details
Name: | fss_TaxActTransitionTaxrateappliedtoearningsinexcessofcash
Namespace Prefix: | fss_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tax Credit Carryforward, Expiration Year + References No definition available. + Details
Name: | fss_TaxCreditCarryforwardExpirationYear
Namespace Prefix: | fss_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32621-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 25 -Paragraph 20 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=68052875&loc=d3e28680-109314 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32632-109319 + Details
Name: | us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign operating loss carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32621-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32632-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 25 -Paragraph 20 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=68052875&loc=d3e28680-109314 + Details
Name: | us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32632-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32621-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 25 -Paragraph 20 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=68052875&loc=d3e28680-109314 + Details
Name: | us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Alternative Minimum Tax -URI http://asc.fasb.org/extlink&oid=6504908 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32559-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32632-109319 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32621-109319 + Details
Name: | us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign tax credit carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32559-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32621-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32632-109319 + Details
Name: | us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32621-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32632-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32559-109319 + Details
Name: | us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(2)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32687-109319 + Details
Name: | us-gaap_EffectiveIncomeTaxRateContinuingOperations
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32639-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Income Tax Expense (or Benefit) -URI http://asc.fasb.org/extlink&oid=6515339 + Details
Name: | us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e32123-109318 + Details
Name: | us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e32059-109318 + Details
Name: | us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3536-108585 + Details
Name: | us-gaap_IncomeTaxesPaid
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of unrecognized tax benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Unrecognized Tax Benefit -URI http://asc.fasb.org/extlink&oid=6527854 + Details
Name: | us-gaap_UnrecognizedTaxBenefits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of statutory penalties accrued for a tax position claimed or expected to be claimed by the entity, in its tax return. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32718-109319 + Details
Name: | us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32718-109319 + Details
Name: | us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of increase (decrease) in unrecognized tax benefits attributable to uncertain tax positions taken in tax returns. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319 + Details
Name: | us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e32123-109318 + Details
Name: | us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_TaxCreditCarryforwardAxis=us-gaap_ResearchMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=country_CA
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_InternalRevenueServiceIRSMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TaxCreditCarryforwardAxis=fss_ForeignTaxCreditCarryforwardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalJurisdictionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignCountryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=country_GB
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=fss_CurrentDeferredTaxAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementScenarioAxis=fss_TaxlawchangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |