Basis of Presentation	6 Months Ended
Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements of Hologic, Inc. (“Hologic” or the “Company”) presented herein have been prepared pursuant to the rules of the Securities and Exchange Commission (“SEC”) for quarterly reports on Form 10-Q and do not include all of the information and disclosures required by U.S. generally accepted accounting principles (“GAAP”) for annual financial statements. These financial statements should be read in conjunction with the consolidated financial statements and related notes for the year ended September 30, 2017 included in the Company’s Form 10-K filed with the SEC on November 21, 2017. In the opinion of management, the financial statements and notes contain all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the Company’s financial position, results of operations and cash flows for the periods presented. The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. The preparation of financial statements in conformity with U.S. GAAP requires management to make significant estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from management’s estimates if past experience or other assumptions do not turn out to be substantially accurate. Operating results for the three and six months ended March 31, 2018 are not necessarily indicative of the results to be expected for any other interim period or the entire fiscal year ending September 29, 2018. On March 22, 2017, the Company completed the acquisition of Cynosure, Inc. ("Cynosure"), which resulted in the Company expanding into the medical aesthetics market. Cynosure develops, manufactures and markets aesthetic treatment systems that enable medical practitioners to perform non-invasive and minimally invasive procedures. Cynosure's results of operations are reported within the Company's Medical Aesthetics reportable segment. The Company's acquisition of Cynosure is more fully described in Note 3. Recently Adopted Accounting Pronouncements In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (ASU 2017-04). This guidance simplifies how companies calculate goodwill impairments by eliminating Step 2 of the impairment test. The guidance requires companies to compare the fair value of a reporting unit to its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. The guidance is effective for annual periods beginning after December 15, 2019, and is applicable to the Company in fiscal 2020. Early adoption is allowed and the Company adopted ASU 2017-04 in the second quarter of fiscal 2018. The Company applied this standard to the interim goodwill impairment test of the Medical Aesthetics reporting unit. No other reporting units required an interim impairment test. The interim goodwill impairment test is more fully described in Note 14. In December 2016, the FASB issued Accounting Standards Update No. 2016-19, Technical Corrections and Improvements (ASU 2016-19). This guidance changes how companies classify internal-use software from classification within property, plant, and equipment to intangible assets. The amendments in the update are effective for annual periods beginning after December 15, 2016, and were applicable to the Company in fiscal 2018. The Company adopted ASU 2016-19 in the first quarter of fiscal 2018 and has reclassified $18.4 million of internal-use software from property, plant, and equipment to intangible assets as of September 30, 2017. Additionally, the Company reclassified $12.3 million of capitalized software embedded in its products from other assets to intangible assets as of September 30, 2017. Subsequent Events Consideration The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the financial statements to provide additional evidence for certain estimates or to identify matters that may require additional disclosure. Subsequent events have been evaluated as required. There were no material recognized or unrecognized subsequent events recorded in the unaudited consolidated financial statements as of and for the three and six months ended March 31, 2018.

Basis of Presentation

The consolidated financial statements of Hologic, Inc. (“Hologic” or the “Company”) presented herein have been prepared pursuant to the rules of the Securities and Exchange Commission (“SEC”) for quarterly reports on Form 10-Q and do not include all of the information and disclosures required by U.S. generally accepted accounting principles (“GAAP”) for annual financial statements. These financial statements should be read in conjunction with the consolidated financial statements and related notes for the year ended September 30, 2017 included in the Company’s Form 10-K filed with the SEC on November 21, 2017. In the opinion of management, the financial statements and notes contain all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the Company’s financial position, results of operations and cash flows for the periods presented.

The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

The preparation of financial statements in conformity with U.S. GAAP requires management to make significant estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from management’s estimates if past experience or other assumptions do not turn out to be substantially accurate. Operating results for the three and six months ended March 31, 2018 are not necessarily indicative of the results to be expected for any other interim period or the entire fiscal year ending September 29, 2018.

On March 22, 2017, the Company completed the acquisition of Cynosure, Inc. ("Cynosure"), which resulted in the Company expanding into the medical aesthetics market. Cynosure develops, manufactures and markets aesthetic treatment systems that enable medical practitioners to perform non-invasive and minimally invasive procedures. Cynosure's results of operations are reported within the Company's Medical Aesthetics reportable segment. The Company's acquisition of Cynosure is more fully described in Note 3.

Recently Adopted Accounting Pronouncements

In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (ASU 2017-04). This guidance simplifies how companies calculate goodwill impairments by eliminating Step 2 of the impairment test. The guidance requires companies to compare the fair value of a reporting unit to its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. The guidance is effective for annual periods beginning after December 15, 2019, and is applicable to the Company in fiscal 2020. Early adoption is allowed and the Company adopted ASU 2017-04 in the second quarter of fiscal 2018. The Company applied this standard to the interim goodwill impairment test of the Medical Aesthetics reporting unit. No other reporting units required an interim impairment test. The interim goodwill impairment test is more fully described in Note 14.

In December 2016, the FASB issued Accounting Standards Update No. 2016-19, Technical Corrections and Improvements (ASU 2016-19). This guidance changes how companies classify internal-use software from classification within property, plant, and equipment to intangible assets. The amendments in the update are effective for annual periods beginning after December 15, 2016, and were applicable to the Company in fiscal 2018. The Company adopted ASU 2016-19 in the first quarter of fiscal 2018 and has reclassified $18.4 million of internal-use software from property, plant, and equipment to intangible assets as of September 30, 2017. Additionally, the Company reclassified $12.3 million of capitalized software embedded in its products from other assets to intangible assets as of September 30, 2017.

Subsequent Events Consideration

The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the financial statements to provide additional evidence for certain estimates or to identify matters that may require additional disclosure. Subsequent events have been evaluated as required. There were no material recognized or unrecognized subsequent events recorded in the unaudited consolidated financial statements as of and for the three and six months ended March 31, 2018.