Legal Matters and Contingencies - Estimated Asbestos Liability (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Liability for Asbestos and Environmental Claims, Net [Roll Forward]
Beginning balance, January 1,	$ 98,652	$ 94,423
Asbestos liability adjustments, net	(106)	0
Cash payment activity	(3,766)	(1,204)
Other, net	(1,495)	(967)
Ending balance, March 31,	$ 93,285	$ 92,252

Liability For Asbestos And Environmental Claims, Net, Other Adjustments

No definition available.

Name:	fls_LiabilityForAsbestosAndEnvironmentalClaimsNetOtherAdjustments
Namespace Prefix:	fls_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
-URI https://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

+ Details

Name:	us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

+ Details

Name:	us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetIncurredLoss1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

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

- 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

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