Stock-Based Compensation	6 Months Ended
Stock-Based Compensation	Jun. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation On May 3, 2016, at our 2016 Annual Meeting of Shareholders, our shareholders approved the adoption of the West Pharmaceutical Services, Inc. 2016 Omnibus Incentive Compensation Plan (the “2016 Plan”). All remaining shares available for issuance under the 2011 Omnibus Incentive Compensation Plan (the "2011 Plan") were extinguished upon adoption of the 2016 Plan. Awards granted under previous plans remain outstanding until expiration or settlement. The 2016 Plan provides for the granting of stock options, stock appreciation rights, restricted stock awards and performance awards to employees and non-employee directors. A committee of the Board of Directors determines the terms and conditions of awards to be granted. Vesting requirements vary by award. At inception, there were 5,500,000 shares of common stock available for issuance under the 2016 Plan. Stock options and stock appreciation rights reduce the number of shares available by one share for each award granted. All other awards under the 2016 Plan will reduce the total number of shares available for grant by an amount equal to 2.5 times the number of shares awarded. If awards made under previous plans would entitle a plan participant to an amount of West stock in excess of the target amount, the additional shares (up to a maximum threshold amount) will be distributed under the 2016 Plan. At June 30, 2016, there were 5,441,195 shares remaining in the 2016 Plan for future grants. During the six months ended June 30, 2016, we granted 589,428 stock options at a weighted average exercise price of $61.55 per share based on the grant-date fair value of our stock to key employees under the 2011 and 2016 Plans. The weighted average grant date fair value of options granted was $11.92 per share as determined by the Black-Scholes option valuation model using the following weighted average assumptions: a risk-free interest rate of 1.39%; expected life of 5.9 years based on prior experience; stock volatility of 21.0% based on historical data; and a dividend yield of 1.0%. Stock option expense is recognized over the vesting period, net of forfeitures. During the six months ended June 30, 2016, we granted 110,595 performance vesting share (“PVS”) awards at a weighted average grant-date fair value of $59.93 per share to key employees under the 2011 and 2016 Plans. Each PVS award entitles the holder to one share of our common stock if the annual growth rate of revenue and return on invested capital targets are achieved over a three-year performance period. Shares earned under PVS awards may vary from 0% to 200% of an employee’s targeted award. The fair value of PVS awards is based on the market price of our stock at the grant date and is recognized as expense over the performance period, adjusted for estimated target outcomes and net of forfeitures. Total stock-based compensation expense was $4.9 million and $9.5 million for the three and six months ended June 30, 2016, respectively. For the three and six months ended June 30, 2015, stock-based compensation expense was $15.5 million and $20.8 million, respectively. Included in the 2015 amounts was a $10.4 million charge related to executive retirements, which was recorded within other expense. Refer to Note 12, Other Expense, for further discussion of this charge. The remainder of 2015 stock-based compensation expense was recorded within selling, general and administrative expenses.