Other (Income) Expense (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Income and Expenses [Abstract]
License Cost	$ 1.2	$ 0	$ 0
Development income	(1.6)wst_DevelopmentIncome	(2.0)wst_DevelopmentIncome	(6.5)wst_DevelopmentIncome
Acquisition-related contingencies	1.1	1.0	1.2
Foreign exchange and other	0.9us-gaap_OtherOperatingIncomeExpenseNet	(0.5)us-gaap_OtherOperatingIncomeExpenseNet	(1.1)us-gaap_OtherOperatingIncomeExpenseNet
Restructuring and related charges	0wst_RestructuringRelatedChargesTotal	0wst_RestructuringRelatedChargesTotal	2.1wst_RestructuringRelatedChargesTotal
Impairment charge	0us-gaap_OtherAssetImpairmentCharges	0us-gaap_OtherAssetImpairmentCharges	3.4us-gaap_OtherAssetImpairmentCharges
Other Income Expense	$ 0.2wst_OtherIncomeExpense	$ 0.5wst_OtherIncomeExpense	$ (1.3)wst_OtherIncomeExpense

Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 4

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e7008-128479

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- Definition

The charge against earnings resulting from the write down of long lived assets other than goodwill due to the difference between the carrying value and lower fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-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 360

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230

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- Definition

The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations.

+ References

No definition available.

+ Details

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- Definition

The amount of the write-off for research and development assets that were acquired in a transaction other than a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16265-109275

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- Definition

The amount of consideration recognized during the period under a development, licensing and supply agreement entered into with a customer.

+ References

No definition available.

+ Details

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Namespace Prefix:	wst_
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- Definition

The total amount of other income and expense items that are associated with the entity's normal revenue producing operation.

+ References

No definition available.

+ Details

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- Definition

Total amount charged against earnings in the period for incurred and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, excluding asset retirement obligations. Also includes asset writeoffs and impairment charges.

+ References

No definition available.

+ Details

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