Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The condensed consolidated financial statements included in this report are unaudited and have been prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“U.S. GAAP”) for interim financial reporting and U.S. Securities and Exchange Commission (“SEC”) regulations. The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. In the opinion of management, these financial statements include all adjustments, which are of a normal recurring nature, necessary for a fair statement of the financial position, results of operations, cash flows and the change in equity for the periods presented. The condensed consolidated financial statements for the three months ended March 31, 2024, should be read in conjunction with the consolidated financial statements and notes thereto of West Pharmaceutical Services, Inc. and its majority-owned subsidiaries (which may be referred to as “West,” the “Company,” “we,” “us” or “our”) appearing in our Annual Report on Form 10-K for the year ended December 31, 2023 (the “2023 Annual Report”). The results of operations for any interim period are not necessarily indicative of results for the full year.
Standards Issued Not Yet Adopted	Standards Issued Not Yet Adopted In November 2023, the Financial Accounting Standards Board ("FASB") issued guidance that seeks to improve reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. The amendment enhances interim disclosure requirements, clarifies circumstances in which an entity can disclose multiple segment measures of profit or loss, provides new segment disclosure requirements for entities with a single reportable segment, and contains other disclosure requirements. This guidance is effective for fiscal years beginning after December 15, 2023 and interim periods beginning after December 15, 2024. We are currently evaluating the impact of this guidance on our financial statements and disclosures. The Company does not expect such adoption to cause a material impact to the consolidated financial statements and disclosures. In December 2023, the FASB issued guidance that seeks to enhance income tax disclosures to provide information to better assess how an entity's operations and related tax risks affect its tax rate and prospects for future cash flows. Within the income tax rate reconciliation, the amendment requires disclosure of additional categories and greater detail about individual reconciling items over a specified threshold. It also requires information pertaining to taxes paid to be disaggregated for federal, state, and foreign taxes and further disaggregated for specific jurisdictions over a specified threshold. This guidance is effective for fiscal years beginning after December 15, 2024. We are currently evaluating the impact of this guidance on our financial statements and disclosures, but we expect adoption will cause a significant impact to our Income Taxes footnote disclosure.
Fair Value Measurement	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The following fair value hierarchy classifies the inputs to valuation techniques used to measure fair value into one of three levels: •Level 1: Unadjusted quoted prices in active markets for identical assets or liabilities. •Level 2: Inputs other than quoted prices that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. •Level 3: Unobservable inputs that reflect the reporting entity’s own assumptions.