XML 65 R54.htm IDEA: XBRL DOCUMENT
v3.21.1

Fair Value Measurement - Level 3 Fair Value Measurements (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2021 | Dec. 31, 2020
Level 3 Fair Value Measurements [Roll Forward] |  |
Balance, beginning of period | $ 3.6 | $ 3.3
Increase in fair value recorded in earnings | 0.7 | 1.2
Payments | (0.4) | (0.9)
Balance, end of period | $ 3.9 | $ 3.6
Sales Projections | Minimum |  |
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items] |  |
Business combination, contingent consideration, measurement input | 10.00% |
Sales Projections | Maximum |  |
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items] |  |
Business combination, contingent consideration, measurement input | 50.00% |
Sales Projections | Weighted Average |  |
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items] |  |
Business combination, contingent consideration, measurement input | 40.00% |
Probabilities of Successful FDA Approval | Minimum |  |
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items] |  |
Business combination, contingent consideration, measurement input | 19.00% |
Probabilities of Successful FDA Approval | Maximum |  |
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items] |  |
Business combination, contingent consideration, measurement input | 100.00% |
Probabilities of Successful Execution of Agreement | Minimum |  |
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items] |  |
Business combination, contingent consideration, measurement input | 25.00% |
Probabilities of Successful Execution of Agreement | Maximum |  |
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items] |  |
Business combination, contingent consideration, measurement input | 100.00% |
Measurement Input, Discount Rate |  |
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items] |  |
Business combination, contingent consideration, measurement input | 19.00% |

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

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

X
- Definition Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Business Combination, Contingent Consideration, Measurement Input + References No definition available. + Details
Name: | wst_BusinessCombinationContingentConsiderationMeasurementInput
Namespace Prefix: | wst_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=wst_SalesProjectionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=wst_ProbabilitiesOfSuccessfulFDAApprovalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=wst_ProbabilitiesOfSuccessfulExecutionOfAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |