Legal Matters and Contingencies - Estimated Asbestos Liability (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024
Liability for Asbestos and Environmental Claims, Net [Roll Forward]
Beginning balance, January 1,	$ 110,332	$ 102,903
Asbestos liability adjustments, net	52,358	23,740
Cash payment activity	(10,632)	(7,089)
Other, net	(7,948)	(4,187)
Ending balance, September 30,	$ 144,110	$ 115,367

Liability For Asbestos And Environmental Claims, Net, Other Adjustments

No definition available.

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Namespace Prefix:	fls_
Data Type:	xbrli:monetaryItemType
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- Definition

Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos and environmental claims, net of estimated reinsurance recoveries.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (cc)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-3

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-3

+ Details

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- Definition

Amount, after effects of reinsurance, of expense for claims incurred and costs incurred in the claim settlement process attributable to asbestos and environmental claims.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-3

+ Details

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Balance Type:	debit
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- Definition

Amount, after effects of reinsurance, of payments to settle insured claims and pay costs incurred in the claims settlement process attributable to asbestos and environmental claims.

+ References

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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