Basis of Presentation	12 Months Ended
Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	On September 16, 2015, the Air Products and Chemicals, Inc. (“Air Products”) Board of Directors announced its intention to separate (the “Separation”) Air Products’ Materials Technologies business, into a newly formed company, Versum Materials, LLC. In September 2016, Versum Materials, LLC was converted from a limited liability company to a Delaware corporation, Versum Materials, Inc. On October 1, 2016, Air Products completed the Separation by distributing to its stockholders one share of common stock of Versum for every two shares of Air Product’s common stock in a distribution intended to be tax-free to Air Products stockholders (the “Distribution”). As a result of the Distribution, Versum is now an independent public company and its common stock is listed under the symbol “VSM” on the New York Stock Exchange. The accompanying Annual Combined Financial Statements of Versum, a business of Air Products, have been prepared on a standalone basis and are derived from Air Products’ consolidated financial statements and accounting records where Electronic Materials is a division of Air Products. The Annual Combined Financial Statements were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of Versum. All significant intercompany transactions and balances have been eliminated in the preparation of the accompanying Annual Combined Financial Statements. Transactions between Versum and Air Products are reflected in the annual combined balance sheets as “Air Products’ net investment” and in the annual combined statements of cash flows as a financing activity in “Net transfers (to) from Air Products.” We are a global business that provides innovative solutions for specific customer applications within niche markets based upon expertise in specialty materials. Our business employs applications technology to provide solutions to the semiconductor industry through chemical synthesis, analytical technology, process engineering, and surface science. We are comprised of two primary operating segments, Materials and Delivery Systems and Services, under which we manage our operations and assess performance, and a Corporate segment. Air Products provides us with centrally managed services and corporate functions. Accordingly, certain shared costs including but not limited to administrative expenses for information technology, general services, human resources, legal, accounting and other services, have been allocated to us and are reflected as expenses in the Annual Combined Financial Statements. Expenses have been allocated on the basis of direct usage when identifiable, with the remainder allocated on the basis of fixed costs, revenue, operating income or headcount. We consider the expense allocation methodology and results to be reasonable and consistently applied for all periods presented. However, these allocations may not be indicative of the actual expenses we would have incurred as an independent public company or of the costs we will incur in the future. The annual combined balance sheets of Versum include Air Products’ assets and liabilities that are specifically identifiable or were otherwise transferred to us, including subsidiaries and affiliates in which Air Products has a controlling financial interest. Also included within our Annual Combined Financial Statements are the results of certain product lines which have historically been managed by us but were retained by Air Products after the Separation. These product lines represented approximately 1% and 1% of annual combined sales and operating income, respectively, for fiscal year 2016. Air Products performs cash management and other treasury-related functions on a centralized basis for nearly all of its legal entities. Substantially all cash generated by our business is remitted to Air Products and therefore accounted for through Air Products’ net investment in the Annual Combined Financial Statements. Accordingly, Air Products has not allocated any centrally managed cash and cash items to us in the Annual Combined Financial Statements. Air Products’ debt and related interest expense have not been allocated to us for any of the periods presented since we are not the legal obligor of the debt, and Air Products’ borrowings were not directly attributable to us. There were no other financing arrangements between us and Air Products during the periods presented. The annual combined balance sheets include cash and cash items and debt which are assets and liabilities of legal entities whose operations are specific to Versum.

On September 16, 2015, the Air Products and Chemicals, Inc. (“Air Products”) Board of Directors announced its intention to separate (the “Separation”) Air Products’ Materials Technologies business, into a newly formed company, Versum Materials, LLC. In September 2016, Versum Materials, LLC was converted from a limited liability company to a Delaware corporation, Versum Materials, Inc. On October 1, 2016, Air Products completed the Separation by distributing to its stockholders one share of common stock of Versum for every two shares of Air Product’s common stock in a distribution intended to be tax-free to Air Products stockholders (the “Distribution”). As a result of the Distribution, Versum is now an independent public company and its common stock is listed under the symbol “VSM” on the New York Stock Exchange.

The accompanying Annual Combined Financial Statements of Versum, a business of Air Products, have been prepared on a standalone basis and are derived from Air Products’ consolidated financial statements and accounting records where Electronic Materials is a division of Air Products. The Annual Combined Financial Statements were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of Versum. All significant intercompany transactions and balances have been eliminated in the preparation of the accompanying Annual Combined Financial Statements. Transactions between Versum and Air Products are reflected in the annual combined balance sheets as “Air Products’ net investment” and in the annual combined statements of cash flows as a financing activity in “Net transfers (to) from Air Products.”

We are a global business that provides innovative solutions for specific customer applications within niche markets based upon expertise in specialty materials. Our business employs applications technology to provide solutions to the semiconductor industry through chemical synthesis, analytical technology, process engineering, and surface science. We are comprised of two primary operating segments, Materials and Delivery Systems and Services, under which we manage our operations and assess performance, and a Corporate segment.

Air Products provides us with centrally managed services and corporate functions. Accordingly, certain shared costs including but not limited to administrative expenses for information technology, general services, human resources, legal, accounting and other services, have been allocated to us and are reflected as expenses in the Annual Combined Financial Statements. Expenses have been allocated on the basis of direct usage when identifiable, with the remainder allocated on the basis of fixed costs, revenue, operating income or headcount. We consider the expense allocation methodology and results to be reasonable and consistently applied for all periods presented. However, these allocations may not be indicative of the actual expenses we would have incurred as an independent public company or of the costs we will incur in the future.

The annual combined balance sheets of Versum include Air Products’ assets and liabilities that are specifically identifiable or were otherwise transferred to us, including subsidiaries and affiliates in which Air Products has a controlling financial interest. Also included within our Annual Combined Financial Statements are the results of certain product lines which have historically been managed by us but were retained by Air Products after the Separation. These product lines represented approximately 1% and 1% of annual combined sales and operating income, respectively, for fiscal year 2016. Air Products performs cash management and other treasury-related functions on a centralized basis for nearly all of its legal entities. Substantially all cash generated by our business is remitted to Air Products and therefore accounted for through Air Products’ net investment in the Annual Combined Financial Statements. Accordingly, Air Products has not allocated any centrally managed cash and cash items to us in the Annual Combined Financial Statements. Air Products’ debt and related interest expense have not been allocated to us for any of the periods presented since we are not the legal obligor of the debt, and Air Products’ borrowings were not directly attributable to us. There were no other financing arrangements between us and Air Products during the periods presented.

The annual combined balance sheets include cash and cash items and debt which are assets and liabilities of legal entities whose operations are specific to Versum.