XML 104 R90.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Segment Information (Sales by Product Group) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Segment Reporting, Revenue Reconciling Items [Line Items] |  |  |
Net sales | $ 1,599.1 | $ 1,509.1 | $ 1,399.8
Contract-Manufactured Products [Member] |  |  |
Segment Reporting, Revenue Reconciling Items [Line Items] |  |  |
Net sales | 362.5 | 320.2 | 302.4
Proprietary Products [Member] |  |  |
Segment Reporting, Revenue Reconciling Items [Line Items] |  |  |
Net sales | 1,236.9 | 1,189.9 | 1,098.3
Intersegment Elimination [Member] |  |  |
Segment Reporting, Revenue Reconciling Items [Line Items] |  |  |
Net sales | $ (0.3) | $ (1.0) | $ (0.9)

X
- Definition Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts. + 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 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_SalesRevenueNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=wst_ContractManufacturingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=wst_ProprietaryProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |