Segment Information (Sales and PPE by Geographic Location) (Details) (USD $) In Millions, unless otherwise specified
|
12 Months Ended |
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
Revenues from External Customers and Long-Lived Assets [Line Items] |
|
|
|
Sales |
$ 1,421.4us-gaap_SalesRevenueNet |
$ 1,368.4us-gaap_SalesRevenueNet |
$ 1,266.4us-gaap_SalesRevenueNet |
Property, Plant and Equipment, Net |
705.8us-gaap_PropertyPlantAndEquipmentNet |
711.7us-gaap_PropertyPlantAndEquipmentNet |
669.0us-gaap_PropertyPlantAndEquipmentNet |
United States [Member] |
|
|
|
Revenues from External Customers and Long-Lived Assets [Line Items] |
|
|
|
Sales |
655.5us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_US |
614.5us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_US |
592.8us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_US |
Property, Plant and Equipment, Net |
339.4us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US |
336.0us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US |
322.0us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US |
Germany [Member] |
|
|
|
Revenues from External Customers and Long-Lived Assets [Line Items] |
|
|
|
Sales |
219.4us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_DE |
219.6us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_DE |
184.4us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_DE |
Property, Plant and Equipment, Net |
110.9us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_DE |
124.4us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_DE |
117.2us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_DE |
France [Member] |
|
|
|
Revenues from External Customers and Long-Lived Assets [Line Items] |
|
|
|
Sales |
118.2us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_FR |
112.6us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_FR |
102.6us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = country_FR |
Property, Plant and Equipment, Net |
40.4us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_FR |
43.4us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_FR |
42.1us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_FR |
Other European Countries [Member] |
|
|
|
Revenues from External Customers and Long-Lived Assets [Line Items] |
|
|
|
Sales |
285.0us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = wst_OtherEuropeCountriesMember |
279.4us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = wst_OtherEuropeCountriesMember |
251.4us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = wst_OtherEuropeCountriesMember |
Property, Plant and Equipment, Net |
91.5us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = wst_OtherEuropeCountriesMember |
83.2us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = wst_OtherEuropeCountriesMember |
72.3us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = wst_OtherEuropeCountriesMember |
Other [Member] |
|
|
|
Revenues from External Customers and Long-Lived Assets [Line Items] |
|
|
|
Sales |
143.3us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = wst_OtherCountriesMember |
142.3us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = wst_OtherCountriesMember |
135.2us-gaap_SalesRevenueNet / us-gaap_StatementGeographicalAxis = wst_OtherCountriesMember |
Property, Plant and Equipment, Net |
$ 123.6us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = wst_OtherCountriesMember |
$ 124.7us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = wst_OtherCountriesMember |
$ 115.4us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = wst_OtherCountriesMember |