Basis of Presentation	3 Months Ended
Dec. 30, 2017
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”). 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 months ended December 30, 2017 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 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. As a result of the adoption, the Company has reclassified $17.6 million and $18.4 million of internal-use software from property, plant, and equipment to intangible assets as of December 30, 2017 and September 30, 2017, respectively. Additionally, the Company reclassified $12.9 million and $12.3 million of capitalized software embedded in its products from other assets to intangible assets as of December 30, 2017 and September 30, 2017, respectively. 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 months ended December 30, 2017. On January 19, 2018, the Company completed a private placement of $1.0 billion aggregate principal amount of senior notes, allocated between (i) $600 million of its 4.375% Senior Notes due 2025 (the “New 2025 Senior Notes”) at an offering price of 100% of the aggregate principal amount of the 2025 Senior Notes, plus accrued and unpaid interest from October 10, 2017, and (ii) $400 million of its new 4.625% Senior Notes due 2028 (the "2028 Senior Notes," and together with the New 2025 Senior Notes, the "New Notes") at an offering price of 100% of the aggregate principal amount of the 2028 Senior Notes. In connection with the offering of the New Notes, the Company has called all of its outstanding 5.250% Senior Notes due 2022 (the "2022 Senior Notes"), in aggregate principal amount of $1.0 billion, for redemption on February 15, 2018 at an aggregate redemption price equal to the principal amount of the outstanding 2022 Senior Notes, plus the applicable premium and accrued and unpaid interest through the day immediately preceding the redemption date. Additionally, on January 29, 2018, the Company announced that pursuant to the terms of the indenture for the 2.00% Convertible Senior Notes due 2042 (the “2042 Notes”), holders of the 2042 Notes had the option of requiring the Company to repurchase their 2042 Notes on March 1, 2018 at a repurchase price payable in cash equal to 100% of the accreted principal amount of the 2042 Notes, plus accrued and unpaid interest to, but not including the put date. The Company also announced on January 29, 2018 that it had elected to redeem, on March 6, 2018, all of the then outstanding 2042 Notes at a redemption price payable in cash equal to 100% of the accreted principal amount of the 2042 Notes, plus accrued and unpaid interest to, but not including the redemption date. Holders also have a right to convert their 2042 Notes. In connection with holders’ right to convert the 2042 Notes, the Company announced that it would settle all conversions of 2042 Notes entirely in cash.

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”). 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 months ended December 30, 2017 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 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. As a result of the adoption, the Company has reclassified $17.6 million and $18.4 million of internal-use software from property, plant, and equipment to intangible assets as of December 30, 2017 and September 30, 2017, respectively. Additionally, the Company reclassified $12.9 million and $12.3 million of capitalized software embedded in its products from other assets to intangible assets as of December 30, 2017 and September 30, 2017, respectively.

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 months ended December 30, 2017. On January 19, 2018, the Company completed a private placement of $1.0 billion aggregate principal amount of senior notes, allocated between (i) $600 million of its 4.375% Senior Notes due 2025 (the “New 2025 Senior Notes”) at an offering price of 100% of the aggregate principal amount of the 2025 Senior Notes, plus accrued and unpaid interest from October 10, 2017, and (ii) $400 million of its new 4.625% Senior Notes due 2028 (the "2028 Senior Notes," and together with the New 2025 Senior Notes, the "New Notes") at an offering price of 100% of the aggregate principal amount of the 2028 Senior Notes. In connection with the offering of the New Notes, the Company has called all of its outstanding 5.250% Senior Notes due 2022 (the "2022 Senior Notes"), in aggregate principal amount of $1.0 billion, for redemption on February 15, 2018 at an aggregate redemption price equal to the principal amount of the outstanding 2022 Senior Notes, plus the applicable premium and accrued and unpaid interest through the day immediately preceding the redemption date.

Additionally, on January 29, 2018, the Company announced that pursuant to the terms of the indenture for the 2.00% Convertible Senior Notes due 2042 (the “2042 Notes”), holders of the 2042 Notes had the option of requiring the Company to repurchase their 2042 Notes on March 1, 2018 at a repurchase price payable in cash equal to 100% of the accreted principal amount of the 2042 Notes, plus accrued and unpaid interest to, but not including the put date. The Company also announced on January 29, 2018 that it had elected to redeem, on March 6, 2018, all of the then outstanding 2042 Notes at a redemption price payable in cash equal to 100% of the accreted principal amount of the 2042 Notes, plus accrued and unpaid interest to, but not including the redemption date. Holders also have a right to convert their 2042 Notes. In connection with holders’ right to convert the 2042 Notes, the Company announced that it would settle all conversions of 2042 Notes entirely in cash.