XML 25 R55.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Debt (Textuals) (Details) | 12 Months Ended |  | 12 Months Ended |  | 12 Months Ended |  | 12 Months Ended |  |  | 12 Months Ended |  | 12 Months Ended |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($) | Dec. 31, 2012 USD ($) | Dec. 31, 2014 Senior A Notes Due 2022 [Member] | Dec. 31, 2014 Senior B Notes Due 2024 [Member] | Dec. 31, 2014 Senior C Notes Due 2027 [Member] | Dec. 31, 2014 Revolving Credit Facility Due 2017 [Member] USD ($) | Dec. 31, 2013 Revolving Credit Facility Due 2017 [Member] USD ($) | Dec. 31, 2014 Term Loan Due 2018 [Member] USD ($) | Dec. 31, 2013 Term Loan Due 2018 [Member] USD ($) | Dec. 31, 2014 Series B Floating Rate Notes Due 2015 [Member] USD ($) | Dec. 31, 2013 Series B Floating Rate Notes Due 2015 [Member] USD ($) | Dec. 31, 2014 EURO Note B Due 2016 [Member] USD ($) | Dec. 31, 2014 EURO Note B Due 2016 [Member] EUR (€) | Dec. 31, 2013 EURO Note B Due 2016 [Member] USD ($) | Dec. 31, 2011 Convertible Debt Due 2047 [Member] USD ($) | Dec. 31, 2013 Convertible Debt Due 2047 [Member] USD ($) | Dec. 31, 2012 Convertible Debt Due 2047 [Member] USD ($) | Dec. 31, 2014 Convertible Debt Due 2047 [Member] USD ($) | Dec. 31, 2014 Senior Notes [Member] USD ($) | Dec. 31, 2014 Senior Notes [Member] Senior A Notes Due 2022 [Member] USD ($) | Dec. 31, 2013 Senior Notes [Member] Senior A Notes Due 2022 [Member] USD ($) | Dec. 31, 2014 Senior Notes [Member] Senior B Notes Due 2024 [Member] USD ($) | Dec. 31, 2013 Senior Notes [Member] Senior B Notes Due 2024 [Member] USD ($) | Dec. 31, 2014 Senior Notes [Member] Senior C Notes Due 2027 [Member] USD ($) | Dec. 31, 2013 Senior Notes [Member] Senior C Notes Due 2027 [Member] USD ($) | Dec. 31, 2014 Letter of Credit [Member] Revolving Credit Facility Due 2017 [Member] USD ($)
Line of Credit Facility [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Losses on Extinguishment of Debt | $ 0 us-gaap_GainsLossesOnExtinguishmentOfDebt | $ 200,000 us-gaap_GainsLossesOnExtinguishmentOfDebt | $ 11,600,000 us-gaap_GainsLossesOnExtinguishmentOfDebt |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 200,000 us-gaap_GainsLossesOnExtinguishmentOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember | $ 11,600,000 us-gaap_GainsLossesOnExtinguishmentOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember |  |  |  |  |  |  |  |  |
Gains (Losses) on extinguishment of debt, less than | (100,000)wst_GainsLossesonextinguishmentofdebtlessthan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, expiration date |  |  |  |  |  |  | Apr. 30, 2017 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, current borrowing capacity |  |  |  |  |  |  | 300,000,000.0 us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, maximum borrowing capacity |  |  |  |  |  |  | 350,000,000.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Credit facility is available for swing-line loans |  |  |  |  |  |  | 30,000,000.0 wst_CreditFacilityIsAvailableForSwingLineLoans / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Credit available for the issuance of letters of credit |  |  |  |  |  |  | 30,000,000.0 wst_CreditAvailableForIssuanceOfLettersOfCredit / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of credit interest rate margin added to Libor at minimum (in hundredths) |  |  |  |  |  |  | 1.25 wst_LineofcreditinterestratemarginaddedtoLiboratminimuminhundredths / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of credit interest rate margin added to Libor at maximum (in hundredths) |  |  |  |  |  |  | 2.25 wst_LineofcreditinterestratemarginaddedtoLiboratmaximuminhundredths / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt issuance cost |  |  |  |  |  |  | 2,400,000 us-gaap_DebtIssuanceCosts / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  | 1,200,000 us-gaap_DebtIssuanceCosts / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |  |  |  |  |  |  |
Long-term debt | 336,700,000 us-gaap_LongTermDebt | 373,500,000 us-gaap_LongTermDebt |  |  |  |  | 29,700,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member | 53,700,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member | 39,200,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = wst_TermLoanDue2018Member | 41,300,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = wst_TermLoanDue2018Member | 25,000,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = wst_SeriesBFloatingRateNotesDue2015Member | 25,000,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = wst_SeriesBFloatingRateNotesDue2015Member | 74,300,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = wst_EuroNoteBDue2016Member |  | 84,100,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = wst_EuroNoteBDue2016Member |  | 600,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember |  |  | 168,000,000 us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember | 42,000,000 us-gaap_LongTermDebt / us-gaap_DebtInstrumentAxis = wst_SeniorNotesDue2022Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember | 42,000,000 us-gaap_LongTermDebt / us-gaap_DebtInstrumentAxis = wst_SeniorNotesDue2022Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember | 53,000,000 us-gaap_LongTermDebt / us-gaap_DebtInstrumentAxis = wst_SeniorBNotesDue2024Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember | 53,000,000 us-gaap_LongTermDebt / us-gaap_DebtInstrumentAxis = wst_SeniorBNotesDue2024Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember | 73,000,000 us-gaap_LongTermDebt / us-gaap_DebtInstrumentAxis = wst_SeniorCNotesDue2027Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember | 73,000,000 us-gaap_LongTermDebt / us-gaap_DebtInstrumentAxis = wst_SeniorCNotesDue2027Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |
Long-term Debt, Current Maturities |  |  |  |  |  |  |  |  | 2,100,000 us-gaap_LongTermDebtCurrent / us-gaap_LongtermDebtTypeAxis = wst_TermLoanDue2018Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of credit facility outstanding borrowings, Yen |  |  |  |  |  |  | 4,200,000 wst_LineOfCreditFacilityOutstandingBorrowingsYen / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of credit facility outstanding borrowings, Euro |  |  |  |  |  |  | 25,500,000 wst_LineOfCreditFacilityOutstandingBorrowingsEuro / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit, noncurrent |  |  |  |  |  |  |  | 53,700,000 us-gaap_LongTermLineOfCredit / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,500,000 us-gaap_LineOfCredit / us-gaap_CreditFacilityAxis = us-gaap_LetterOfCreditMember / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member
Line of Credit Facility, unused commitment level |  |  |  |  |  |  | 266,800,000 us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of debt |  |  |  |  |  |  |  |  |  |  |  |  | 10 years | 10 years |  |  |  |  |  |  |  |  |  |  |  |  |
Variable rate basis |  |  |  |  |  |  | LIBOR |  | LIBOR |  | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis spread on variable interest rate |  |  |  |  |  |  |  |  | 1.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_LongtermDebtTypeAxis = wst_TermLoanDue2018Member |  | 0.90%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_LongtermDebtTypeAxis = wst_SeriesBFloatingRateNotesDue2015Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, face amount |  |  |  |  |  |  |  |  | 42,800,000 us-gaap_DebtInstrumentFaceAmount / us-gaap_LongtermDebtTypeAxis = wst_TermLoanDue2018Member |  |  |  |  | 61,100,000 us-gaap_DebtInstrumentFaceAmount / us-gaap_LongtermDebtTypeAxis = wst_EuroNoteBDue2016Member |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Term |  |  |  |  |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, maturity date |  |  |  | Jul. 05, 2022 | Jul. 05, 2024 | Jul. 05, 2027 |  |  | Jan. 31, 2018 |  | Jul. 28, 2015 |  | Feb. 27, 2016 | Feb. 27, 2016 |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, stated interest rate |  |  |  | 3.67%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wst_SeniorNotesDue2022Member | 3.82%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wst_SeniorBNotesDue2024Member | 4.02%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wst_SeniorCNotesDue2027Member | 1.71%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = wst_RevolvingCreditFacilityDue2017Member |  | 1.66%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = wst_TermLoanDue2018Member |  | 1.13%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = wst_SeriesBFloatingRateNotesDue2015Member |  | 4.38%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = wst_EuroNoteBDue2016Member | 4.38%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = wst_EuroNoteBDue2016Member |  |  |  |  | 4.00%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember |  | 3.67%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wst_SeniorNotesDue2022Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |  | 3.82%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wst_SeniorBNotesDue2024Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |  | 4.02%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = wst_SeniorCNotesDue2027Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |  |
Long-term debt, excluding current portion | 309,500,000 us-gaap_LongTermDebtNoncurrent | 371,300,000 us-gaap_LongTermDebtNoncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  | 161,500,000 us-gaap_LongTermDebtNoncurrent / us-gaap_LongtermDebtTypeAxis = wst_ConvertibleDebtDue2047Member |  |  |  |  |  |  |  |  |  |  |
Debt instrument, repurchase amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,500,000 us-gaap_DebtInstrumentRepurchaseAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember | 158,400,000 us-gaap_DebtInstrumentRepurchaseAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember | 600,000 us-gaap_DebtInstrumentRepurchaseAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember |  |  |  |  |  |  |  |
Percentage of convertible debt repurchased |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 98.06%wst_PercentageOfConvertibleDebtRepurchased / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember |  |  |  |  |  |  |  |  |  |
Weighted average of the coupon interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.87%us-gaap_LongtermDebtWeightedAverageInterestRate / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |  |  |  |  |  |  |
Annual effective interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.16%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |  |  |  |  |  |  |
Interest expense | 18,100,000 us-gaap_InterestExpenseDebt | 18,600,000 us-gaap_InterestExpenseDebt | 18,600,000 us-gaap_InterestExpenseDebt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate annual maturities of long-term debt [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2015 | 27,200,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2016 | 76,800,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2017 | 32,100,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2018 | 32,600,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Thereafter | $ 168,000,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentMaturityDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value amount of debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees). + References No definition available. + Details
Name: | us-gaap_DebtIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12317-112629 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12355-112629 + Details
Name: | us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 8 -Article 5 + Details
Name: | us-gaap_InterestExpenseDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_LineOfCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
Name: | us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Date the credit facility terminates, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
Name: | us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
Name: | us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_LongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19,20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19 -Article 5 + Details
Name: | us-gaap_LongTermDebtCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 + Details
Name: | us-gaap_LongTermDebtNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Weighted average interest rate of long-term debt outstanding. + References No definition available. + Details
Name: | us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The carrying value as of the balance sheet date of the noncurrent portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Line-of-Credit Arrangement -URI http://asc.fasb.org/extlink&oid=6517033 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 45 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=28361426&loc=d3e1314-112600 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=28361426&loc=d3e1336-112600 + Details
Name: | us-gaap_LongTermLineOfCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition this refers to Credit available for the issuance of letters of credit + References No definition available. + Details
Name: | wst_CreditAvailableForIssuanceOfLettersOfCredit
Namespace Prefix: | wst_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This refers to credit facility is available for swing-line loans + References No definition available. + Details
Name: | wst_CreditFacilityIsAvailableForSwingLineLoans
Namespace Prefix: | wst_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Debt Instrument, Debt Term + References No definition available. + Details
Name: | wst_DebtInstrumentDebtTerm
Namespace Prefix: | wst_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Gains (Losses) on extinguishment of debt, less than + References No definition available. + Details
Name: | wst_GainsLossesonextinguishmentofdebtlessthan
Namespace Prefix: | wst_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line of credit facility outstanding borrowings, Euro + References No definition available. + Details
Name: | wst_LineOfCreditFacilityOutstandingBorrowingsEuro
Namespace Prefix: | wst_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line of credit facility outstanding borrowings, Yen + References No definition available. + Details
Name: | wst_LineOfCreditFacilityOutstandingBorrowingsYen
Namespace Prefix: | wst_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition this refers to Line of credit interest rate margin added to Libor at maximum (in hundredths) + References No definition available. + Details
Name: | wst_LineofcreditinterestratemarginaddedtoLiboratmaximuminhundredths
Namespace Prefix: | wst_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

X
- Definition this refers to Line of credit interest rate margin added to Libor at minimum (in hundredths) + References No definition available. + Details
Name: | wst_LineofcreditinterestratemarginaddedtoLiboratminimuminhundredths
Namespace Prefix: | wst_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of aggregate principal amount of Convertible Debentures repurchased, as a percentage. + References No definition available. + Details
Name: | wst_PercentageOfConvertibleDebtRepurchased
Namespace Prefix: | wst_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration