Accrued Treasury Shares Cost

No definition available.

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Namespace Prefix:	fss_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount authorized for purchase of share under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481520/505-30-50-4

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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Period Type:	duration

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DividendsPayableLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

The cash outflow to reacquire common stock during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 15
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-15

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

+ References

+ Details

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

- Definition

Number of shares remaining authorized to be purchased under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership.

+ References

No definition available.

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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-Subparagraph (SX 210.5-02(28))
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-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

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-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(4)(b))
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-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3

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-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2))
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-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

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-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

+ Details

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Balance Type:	debit
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- Details

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- Details

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- Details

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Stockholders' Equity - Additional Information (Details) - USD ($)	3 Months Ended
	Jun. 30, 2026	Mar. 31, 2026	Sep. 30, 2025	Mar. 31, 2025	Mar. 13, 2020
Dividends Payable [Line Items]
Cash dividends declared per common share (usd per share)		$ 0.15		$ 0.14
Cash dividends paid to stockholders		$ 9,200,000	$ 9,200,000	$ 8,600,000
Class of Stock Disclosures [Abstract]
Number of shares repurchased				250,604
Treasury stock purchases		0		$ 18,500,000
Treasury Stock, Value, Acquired, Cost Method				$ 19,700,000
Accrued Treasury Shares Cost		$ 1,200,000
Share Repurchase Program, Remaining Authorized, Number of Shares		157,000,000
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased				250,604
Treasury stock purchases		$ 0		$ 18,500,000
Treasury Stock, Value, Acquired, Cost Method				$ 19,700,000
Accrued Treasury Shares Cost		$ 1,200,000
Share Repurchase Program, Remaining Authorized, Number of Shares		157,000,000
Stock Repurchased During Period, Shares				0
Subsequent Event
Dividends Payable [Line Items]
Cash dividends declared per common share (usd per share)	$ 0.15
March 2020 Repurchase Program
Class of Stock Disclosures [Abstract]
Stock repurchase program, authorized amount					$ 75,000,000
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					75,000,000
April 2025 Repurchase Program
Class of Stock Disclosures [Abstract]
Stock repurchase program, authorized amount					150,000,000
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 150,000,000