Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation These interim financial statements of Shire plc and its subsidiaries (collectively “Shire” or the “Company”) are unaudited. They have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”). The Consolidated Balance Sheet as of December 31, 2016 was derived from the Audited Consolidated Financial Statements as of that date. These interim Unaudited Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016, as filed with the SEC on February 22, 2017. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from these interim financial statements. However, these interim financial statements include all adjustments, consisting of normal recurring adjustments, which are, in the opinion of management, necessary to fairly state the results of the interim period and the Company believes that the disclosures are adequate to make the information presented not misleading. Interim results are not necessarily indicative of results to be expected for the full year. On June 3, 2016, the Company completed its acquisition of Baxalta for $32.4 billion, representing the fair value of purchase consideration. The Company’s Unaudited Consolidated Financial Statements include the results of Baxalta from the date of acquisition. For further details regarding the acquisition, refer to Note 2, Business Combinations, of these Unaudited Consolidated Financial Statements. Use of Estimates The preparation of Financial Statements, in conformity with U.S. GAAP and SEC regulations, requires management to make estimates, judgments and assumptions that affect the reported and disclosed amounts of assets, liabilities and equity at the date of the Unaudited Consolidated Financial Statements and reported amounts of revenues and expenses during the period. On an on-going basis, the Company evaluates its estimates, judgments and methodologies. Estimates are based on historical experience, current conditions and on various other assumptions that are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets, liabilities and equity and the amounts of revenues and expenses. Actual results may differ from these estimates under different assumptions or conditions. New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed below, the Company does not believe that the impact of recently issued standards that are not yet effective will have a material impact on the Company’s financial position or results of operations upon adoption. Adopted during the current period Inventory In July 2015, the FASB issued new guidance which requires an entity to measure inventory at the lower of cost and net realizable value. Net realizable value is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company adopted this standard as of January 1, 2017, which did not impact the Company's financial position or results of operations. Share-Based Payment Accounting In March 2016, the FASB issued Accounting Standards Update ("ASU") No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The new standard requires recognition of the income tax effects of vested or settled awards in the income statement and involves several other aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows and allows a one-time accounting policy election to account for forfeitures as they occur. The new standard was effective January 1, 2017. The Company adopted ASU 2016-09 in the first quarter of 2017. Before adoption, excess tax benefits or deficiencies from the Company's equity awards were recorded as Additional paid-in capital in its Consolidated Balance Sheets. Upon adoption, the Company recorded any excess tax benefits or deficiencies from its equity awards in its Consolidated Statements of Operations in the reporting periods in which vesting or settlement occurs. Amendments related to accounting for excess tax benefits have been adopted prospectively, resulting in recognition of excess tax benefits against Income taxes rather than Additional paid-in capital of $11.5 million for the six months ended June 30, 2017. As a result of the adoption, the Company recorded an adjustment to Retained earnings of $39.0 million to recognize net operating loss carryforwards attributable to excess tax benefits on stock compensation that had not been previously recognized to Additional paid-in capital. Excess tax benefits for share-based payments are now included in Net cash provided by operating activities rather than Net cash provided by financing activities. The changes have been applied prospectively in accordance with the ASU and prior periods have not been adjusted. Upon adoption of ASU 2016-09, the Company elected to account for forfeitures in relation to service conditions as they occur. The change was applied on a modified retrospective basis with a cumulative effect adjustment to Retained earnings of $10.7 million as of January 1, 2017. Definition of a Business In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This new standard clarifies the definition of a business and provides guidance to determine when an integrated set of assets and activities is not a business. The Company adopted this standard prospectively on January 1, 2017. To be adopted in future periods Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment. This new standard simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. This standard will be effective for the Company as of January 1, 2020, with early adoption permitted for annual goodwill impairment tests performed after January 1, 2017. The Company does not expect the adoption of this standard to have a material impact on its financial position and results of operations. Revenue from Contracts with Customers In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. The new standard also requires additional qualitative and quantitative disclosures. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delayed the effective date of the new standard from January 1, 2017 to January 1, 2018. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date. The FASB has subsequently issued five additional ASUs amending the guidance in Topic 606, each with the same effective date and transition date of January 1, 2018. This amended guidance has been considered in the Company’s overall assessment of the new standard. Shire will adopt this standard on the effective date of January 1, 2018. The Company is currently evaluating the method of adoption and the potential impact on its financial position and results of operations of adopting this guidance. The Company has identified two primary revenue streams from contracts with customers as part of its initial assessment: 1) product sales and 2) licensing arrangements. Shire is in the process of evaluating these contracts and is not yet able to estimate the anticipated impact to the Company’s financial statements from the application of the new standard. Financial Instrument Accounting In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The new standard amends certain aspects of accounting and disclosure requirements of financial instruments, including the requirement that equity investments with readily determinable fair values be measured at fair value with changes in fair value recognized in the results of operations. This standard will be effective for the Company as of January 1, 2018. The Company is currently evaluating the method of adoption and the potential impact on its financial position and results of operations of adopting this guidance. Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The new accounting guidance will require the recognition of all lease assets and lease liabilities by lessees and sets forth new disclosure requirements for those lease assets and liabilities. The standard requires lessees to recognize right-of-use assets and lease liabilities on the balance sheet using a modified retrospective approach at the beginning of the earliest comparative period in the financial statements. This standard will be effective for the Company as of January 1, 2019. Early adoption is permitted. The Company is currently evaluating the potential impact on its financial position and results of operations of adopting this guidance. Statement of Cash Flows In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The new standard clarifies certain aspects of the statement of cash flows, and aims to reduce diversity in practice regarding how certain transactions are classified in the statement of cash flows. This standard will be effective for the Company as of January 1, 2018. Early adoption is permitted. The adoption of this guidance is not expected to have a significant impact on the Company's Consolidated Statement of Cash Flows. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The new guidance is intended to reduce diversity in the presentation of restricted cash and restricted cash equivalents in the statement. The guidance requires that restricted cash and restricted cash equivalents be included as components of total cash and cash equivalents as presented on the statement of cash flows. This standard will be effective for the Company as of January 1, 2018. The adoption of this guidance is not expected to have a significant impact on the Company's Consolidated Statements of Cash Flows. Income Taxes In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers Other than Inventory. This standard removes the current exception in U.S. GAAP prohibiting entities from recognizing current and deferred income tax expenses or benefits related to transfer of assets, other than inventory, within the consolidated entity. The current exception to defer the recognition of any tax impact on the transfer of inventory within the consolidated entity until it is sold to a third party remains unaffected. This standard will be effective for the Company as of January 1, 2018, with the early adoption permitted. The Company is currently evaluating the method of adoption and the potential impact on its financial position and results of operations of adopting this guidance. Retirement Benefits Income Statement Presentation In March 2017, the FASB issued ASU 2017-07 Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The standard amends the income statement presentation of the components of net periodic benefit cost for defined benefit pension and other postretirement plans. The standard requires entities to (1) disaggregate the current-service-cost component from the other components of net benefit cost (the “other components”) and present it with other current compensation costs for related employees in the income statement and (2) present the other components elsewhere in the income statement and outside of income from operations if such a subtotal is presented. The standard also requires entities to disclose the income statement lines that contain the other components if they are not presented on appropriately described separate lines. This standard will be effective for the Company as of January 1, 2018. The Company does not expect the adoption of this standard to have a material impact on its financial position and results of operations. Share-Based Payment Accounting In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope Modification Accounting. The new standard clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. This standard will be effective for the Company as of January 1, 2018. Early adoption is permitted. The adoption of this guidance is not expected to have a significant impact on the Company’s financial position and results of operations.

Summary of Significant Accounting Policies

Basis of Presentation

These interim financial statements of Shire plc and its subsidiaries (collectively “Shire” or the “Company”) are unaudited. They have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”).

The Consolidated Balance Sheet as of December 31, 2016 was derived from the Audited Consolidated Financial Statements as of that date.

These interim Unaudited Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016, as filed with the SEC on February 22, 2017.

Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from these interim financial statements. However, these interim financial statements include all adjustments, consisting of normal recurring adjustments, which are, in the opinion of management, necessary to fairly state the results of the interim period and the Company believes that the disclosures are adequate to make the information presented not misleading. Interim results are not necessarily indicative of results to be expected for the full year.

On June 3, 2016, the Company completed its acquisition of Baxalta for $32.4 billion, representing the fair value of purchase consideration. The Company’s Unaudited Consolidated Financial Statements include the results of Baxalta from the date of acquisition. For further details regarding the acquisition, refer to Note 2, Business Combinations, of these Unaudited Consolidated Financial Statements.

Use of Estimates

The preparation of Financial Statements, in conformity with U.S. GAAP and SEC regulations, requires management to make estimates, judgments and assumptions that affect the reported and disclosed amounts of assets, liabilities and equity at the date of the Unaudited Consolidated Financial Statements and reported amounts of revenues and expenses during the period. On an on-going basis, the Company evaluates its estimates, judgments and methodologies. Estimates are based on historical experience, current conditions and on various other assumptions that are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets, liabilities and equity and the amounts of revenues and expenses. Actual results may differ from these estimates under different assumptions or conditions.

New Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed below, the Company does not believe that the impact of recently issued standards that are not yet effective will have a material impact on the Company’s financial position or results of operations upon adoption.

Adopted during the current period

Inventory

In July 2015, the FASB issued new guidance which requires an entity to measure inventory at the lower of cost and net realizable value. Net realizable value is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company adopted this standard as of January 1, 2017, which did not impact the Company's financial position or results of operations.

Share-Based Payment Accounting

In March 2016, the FASB issued Accounting Standards Update ("ASU") No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The new standard requires recognition of the income tax effects of vested or settled awards in the income statement and involves several other aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows and allows a one-time accounting policy election to account for forfeitures as they occur. The new standard was effective January 1, 2017.

The Company adopted ASU 2016-09 in the first quarter of 2017. Before adoption, excess tax benefits or deficiencies from the Company's equity awards were recorded as Additional paid-in capital in its Consolidated Balance Sheets. Upon adoption, the Company recorded any excess tax benefits or deficiencies from its equity awards in its Consolidated Statements of Operations in the reporting periods in which vesting or settlement occurs.

Amendments related to accounting for excess tax benefits have been adopted prospectively, resulting in recognition of excess tax benefits against Income taxes rather than Additional paid-in capital of $11.5 million for the six months ended June 30, 2017.

As a result of the adoption, the Company recorded an adjustment to Retained earnings of $39.0 million to recognize net operating loss carryforwards attributable to excess tax benefits on stock compensation that had not been previously recognized to Additional paid-in capital.

Excess tax benefits for share-based payments are now included in Net cash provided by operating activities rather than Net cash provided by financing activities. The changes have been applied prospectively in accordance with the ASU and prior periods have not been adjusted.

Upon adoption of ASU 2016-09, the Company elected to account for forfeitures in relation to service conditions as they occur. The change was applied on a modified retrospective basis with a cumulative effect adjustment to Retained earnings of $10.7 million as of January 1, 2017.

Definition of a Business

In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This new standard clarifies the definition of a business and provides guidance to determine when an integrated set of assets and activities is not a business. The Company adopted this standard prospectively on January 1, 2017.

To be adopted in future periods

Simplifying the Test for Goodwill Impairment

In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment. This new standard simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. This standard will be effective for the Company as of January 1, 2020, with early adoption permitted for annual goodwill impairment tests performed after January 1, 2017. The Company does not expect the adoption of this standard to have a material impact on its financial position and results of operations.

Revenue from Contracts with Customers

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. The new standard also requires additional qualitative and quantitative disclosures.

In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delayed the effective date of the new standard from January 1, 2017 to January 1, 2018. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date.

The FASB has subsequently issued five additional ASUs amending the guidance in Topic 606, each with the same effective date and transition date of January 1, 2018. This amended guidance has been considered in the Company’s overall assessment of the new standard.

Shire will adopt this standard on the effective date of January 1, 2018. The Company is currently evaluating the method of adoption and the potential impact on its financial position and results of operations of adopting this guidance. The Company has identified two primary revenue streams from contracts with customers as part of its initial assessment: 1) product sales and 2) licensing arrangements. Shire is in the process of evaluating these contracts and is not yet able to estimate the anticipated impact to the Company’s financial statements from the application of the new standard.

Financial Instrument Accounting

In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The new standard amends certain aspects of accounting and disclosure requirements of financial instruments, including the requirement that equity investments with readily determinable fair values be measured at fair value with changes in fair value recognized in the results of operations. This standard will be effective for the Company as of January 1, 2018. The Company is currently evaluating the method of adoption and the potential impact on its financial position and results of operations of adopting this guidance.

Leases

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The new accounting guidance will require the recognition of all lease assets and lease liabilities by lessees and sets forth new disclosure requirements for those lease assets and liabilities. The standard requires lessees to recognize right-of-use assets and lease liabilities on the balance sheet using a modified retrospective approach at the beginning of the earliest comparative period in the financial statements. This standard will be effective for the Company as of January 1, 2019. Early adoption is permitted. The Company is currently evaluating the potential impact on its financial position and results of operations of adopting this guidance.

Statement of Cash Flows

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The new standard clarifies certain aspects of the statement of cash flows, and aims to reduce diversity in practice regarding how certain transactions are classified in the statement of cash flows. This standard will be effective for the Company as of January 1, 2018. Early adoption is permitted. The adoption of this guidance is not expected to have a significant impact on the Company's Consolidated Statement of Cash Flows.

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The new guidance is intended to reduce diversity in the presentation of restricted cash and restricted cash equivalents in the statement. The guidance requires that restricted cash and restricted cash equivalents be included as components of total cash and cash equivalents as presented on the statement of cash flows. This standard will be effective for the Company as of January 1, 2018. The adoption of this guidance is not expected to have a significant impact on the Company's Consolidated Statements of Cash Flows.

Income Taxes

In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers Other than Inventory. This standard removes the current exception in U.S. GAAP prohibiting entities from recognizing current and deferred income tax expenses or benefits related to transfer of assets, other than inventory, within the consolidated entity. The current exception to defer the recognition of any tax impact on the transfer of inventory within the consolidated entity until it is sold to a third party remains unaffected. This standard will be effective for the Company as of January 1, 2018, with the early adoption permitted. The Company is currently evaluating the method of adoption and the potential impact on its financial position and results of operations of adopting this guidance.

Retirement Benefits Income Statement Presentation

In March 2017, the FASB issued ASU 2017-07 Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The standard amends the income statement presentation of the components of net periodic benefit cost for defined benefit pension and other postretirement plans. The standard requires entities to (1) disaggregate the current-service-cost component from the other components of net benefit cost (the “other components”) and present it with other current compensation costs for related employees in the income statement and (2) present the other components elsewhere in the income statement and outside of income from operations if such a subtotal is presented. The standard also requires entities to disclose the income statement lines that contain the other components if they are not presented on appropriately described separate lines. This standard will be effective for the Company as of January 1, 2018. The Company does not expect the adoption of this standard to have a material impact on its financial position and results of operations.

Share-Based Payment Accounting

In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope Modification Accounting. The new standard clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. This standard will be effective for the Company as of January 1, 2018. Early adoption is permitted. The adoption of this guidance is not expected to have a significant impact on the Company’s financial position and results of operations.