Stock-Based Compensation (Stock Appreciation Rights Award Activity) (Details) (USD $)
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12 Months Ended | ||
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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SARs, Weighted Average Exercise Price [Roll Forward] | |||
Stock-Settled SARs, Outstanding | 203,540wst_StockSettledStockAppreciationRightsOutstanding | ||
Cash-Settled SARs, Outstanding | 94,174wst_CashSettledStockAppreciationRIghtsOutstanding | ||
Stock Appreciation Rights (SARs) [Member] | |||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
Awards, expiration period | 10 years | ||
SARs Activity [Roll Forward] | |||
Outstanding, Beginning | 375,104us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
389,686us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
320,336us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
Granted | 7,733us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
132,566us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
145,018us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
Exercised | (85,123)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
(147,148)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
(75,668)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
Outstanding, Ending | 297,714us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
375,104us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
389,686us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
Exercisable | 88,751wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
56,938wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
110,292wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
SARs, Weighted Average Exercise Price [Roll Forward] | |||
Oustanding, Beginning (in usd per share) | $ 24.03wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 20.81wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 20.17wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
Granted (in usd per share) | $ 47.74wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 29.56wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 21.22wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
Exercised (in usd per share) | $ 22.09wst_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 20.47wst_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 18.91wst_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
Oustanding, Ending (in usd per share) | $ 25.20wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 24.03wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 20.81wst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
Exercisable (in usd per share) | $ 23.15wst_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 20.95wst_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
$ 20.70wst_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockAppreciationRightsSARSMember |
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- Definition
Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
Number of non-option equity instruments exercised by participants. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Net number of non-option equity instruments granted to participants. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Number of equity instruments other than options outstanding, including both vested and non-vested instruments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
Number of cash-settled stock appreciation rights outstanding. No definition available.
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- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercisable, Number No definition available.
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- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Grants in Period, Weighted Average Exercise Price No definition available.
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- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price No definition available.
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- Details
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- Definition
Share-based Compensation Arrangements by Share-based Payment Award, Non-Option Equity Instruments, Exercisable, Weighted Average Exercise Price No definition available.
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- Definition
Share-based Compensation Arrangements by Share-based Payment Award, Non-Option Equity Instruments, Exercises in Period, Weighted Average Exercise Price No definition available.
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- Definition
Number of stock-settled stock appreciation rights outstanding. No definition available.
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- Details
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