Organization and Basis of Presentation	3 Months Ended
Apr. 29, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Nature of Business Semtech Corporation (together with its consolidated subsidiaries, the "Company" or "Semtech") is a global supplier of analog and mixed-signal semiconductor products. The end customers for the Company’s products are primarily original equipment manufacturers ("OEMs") that produce and sell electronics. The Company designs, develops and markets a wide range of products for commercial applications, the majority of which are sold into the enterprise computing, communications, high-end consumer and industrial end-markets. Enterprise Computing: datacenters, passive optical networks, desktops, notebooks, servers, monitors, printers and other computer peripherals. Communications: base stations, optical networks, carrier networks, switches and routers, cable modems, wireless LAN and other communication infrastructure equipment. High-End Consumer: handheld products, smartphones, wireless charging, set-top boxes, digital televisions, tablets, digital video recorders and other consumer equipment. Industrial: video broadcast equipment, Video-over-IP solutions, automated meter reading, Internet of Things ("IoT"), smart grid, wireless charging, military and aerospace, medical, security systems, automotive, industrial and home automation and other industrial equipment. Fiscal Year The Company reports results on the basis of 52 and 53 week periods and ends its fiscal year on the last Sunday in January. The other quarters generally end on the last Sunday of April, July and October. All quarters consist of 13 weeks except for one 14-week period in the fourth quarter of 53-week years. The first quarter of fiscal years 2019 and 2018 each consisted of 13 weeks. Principles of Consolidation The accompanying interim unaudited consolidated financial statements have been prepared by the Company, in accordance with accounting principles generally accepted in the United States ("GAAP") and on the same basis as the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended January 28, 2018. In the opinion of the Company, these interim unaudited consolidated financial statements contain all adjustments (consisting of normal recurring adjustments) necessary to present fairly, in all material respects, the financial position of the Company for the interim periods presented. All intercompany balances have been eliminated. Certain information and footnote disclosures normally included in annual consolidated financial statements have been condensed or omitted pursuant to the rules and regulations of the U.S. Securities and Exchange Commission. Because the interim unaudited consolidated financial statements do not include all of the information and notes required by GAAP for a complete set of consolidated financial statements, they should be read in conjunction with the audited consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the year ended January 28, 2018. The results reported in these interim unaudited consolidated financial statements should not be regarded as indicative of results that may be expected for any subsequent period or for the entire year. The Company’s interim unaudited consolidated statements of income are referred to herein as the "Statements of Income." The Company’s interim unaudited consolidated balance sheets are referred to herein as the "Balance Sheets" and interim unaudited consolidated statements of cash flows as the "Statements of Cash Flows." Segment Information The Company’s Chief Executive Officer ("CEO") has been identified as the Chief Operating Decision Maker ("CODM") as defined by guidance regarding segment disclosures (see Note 13 for further discussion). Prior to the first quarter of fiscal year 2019, the Company had four operating segments. However as of April 29, 2018, the Company identified three operating segments that aggregate into one reportable segment, the Semiconductor Products Group. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make 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 period. Actual results could differ from those estimates. Recent Accounting Standards Adopted In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Accounting Standards Codification ("ASC") 606), which requires an entity to recognize revenue from the transfer of control of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance addresses, in particular, contracts with more than one performance obligation, as well as the accounting for some costs to obtain or fulfill a contract with a customer, and provides for additional disclosures with respect to revenues and cash flows arising from contracts with customers. The Company adopted the standard, effective January 29, 2018, using the modified retrospective transition method which resulted in an adjustment to retained earnings for the cumulative effect of applying the standard to all contracts not completed as of the adoption date. The primary change associated with the adoption relates to the Company’s sales to distributors with return or price adjustment rights where the Company will no longer defer revenue until the resale by the distributor to the end customer, but rather, will record revenue at the time control transfers to the distributor. The Company estimated the effects of returns and allowances provided to these distributors. Upon adoption, including the effect of income taxes, opening retained earnings as of January 29, 2018 increased by $11.1 million net, as a result of these changes. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Asset Transfers Other Than Inventory (Topic 740). This accounting standard update is aimed at recognizing the income tax consequences of intra-entity transfers of assets other than inventory when they occur. This removes the exception to postpone the recognition of income tax consequences of intra-entity transfers until the asset has been sold to an outside party. In the first quarter of 2019, the Company adopted ASU 2016-16 using a modified retrospective transition method, resulting in a $1.8 million decrease in retained earnings, a $3.7 million net increase in deferred income tax assets, and a $5.5 million decrease in pre-paid taxes. Accounting Guidance Issued but Not Adopted as of April 29, 2018 In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815). This standard addresses narrow issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. Part I addresses the complexity of accounting for certain financial instruments with down round features. Part II addresses the difficulty of navigating Topic 480, Distinguishing Liabilities from Equity, because of the existence of pending content in the ASC that results from the indefinite deferral of accounting requirements concerning mandatorily redeemable financial instruments of certain non-public entities and certain mandatorily redeemable non-controlling interests. The new standard is effective for interim and annual fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company does not expect the adoption of this pronouncement to have a material impact on the Company’s consolidated financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815). The new standard is designed to refine and expand hedge accounting for both financial (e.g., interest rate) and commodity risks. Its provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the footnotes. It also makes certain targeted improvements to simplify the application of hedge accounting guidance. The new standard is effective for interim and annual fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption, including adoption in an interim period, is permitted. The Company is currently evaluating the impact this ASU will have on its consolidated condensed financial statements and disclosures. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will require that substantially all leases be recognized by lessees on their balance sheets as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The new standard also will result in enhanced quantitative and qualitative disclosures, including descriptions of significant judgments made by management, to provide greater insight into the extent of expense recognized and expected to be recognized from existing leases. The standard requires modified retrospective adoption and will be effective for the Company as of the beginning of fiscal year 2020. The Company expects the valuation of right of use assets and lease liabilities, previously described as operating leases, to be the present value of the Company's forecasted future lease commitments. The Company is continuing to assess the overall impacts of the new standard, including the discount rate to be applied in these valuations.

Organization and Basis of Presentation

Nature of Business

Semtech Corporation (together with its consolidated subsidiaries, the "Company" or "Semtech") is a global supplier of analog and mixed-signal semiconductor products. The end customers for the Company’s products are primarily original equipment manufacturers ("OEMs") that produce and sell electronics.

The Company designs, develops and markets a wide range of products for commercial applications, the majority of which are sold into the enterprise computing, communications, high-end consumer and industrial end-markets.

Enterprise Computing: datacenters, passive optical networks, desktops, notebooks, servers, monitors, printers and other computer peripherals.

Communications: base stations, optical networks, carrier networks, switches and routers, cable modems, wireless LAN and other communication infrastructure equipment.

High-End Consumer: handheld products, smartphones, wireless charging, set-top boxes, digital televisions, tablets, digital video recorders and other consumer equipment.

Industrial: video broadcast equipment, Video-over-IP solutions, automated meter reading, Internet of Things ("IoT"), smart grid, wireless charging, military and aerospace, medical, security systems, automotive, industrial and home automation and other industrial equipment.

Fiscal Year

The Company reports results on the basis of 52 and 53 week periods and ends its fiscal year on the last Sunday in January. The other quarters generally end on the last Sunday of April, July and October. All quarters consist of 13 weeks except for one 14-week period in the fourth quarter of 53-week years. The first quarter of fiscal years 2019 and 2018 each consisted of 13 weeks.

Principles of Consolidation

The accompanying interim unaudited consolidated financial statements have been prepared by the Company, in accordance with accounting principles generally accepted in the United States ("GAAP") and on the same basis as the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended January 28, 2018. In the opinion of the Company, these interim unaudited consolidated financial statements contain all adjustments (consisting of normal recurring adjustments) necessary to present fairly, in all material respects, the financial position of the Company for the interim periods presented. All intercompany balances have been eliminated. Certain information and footnote disclosures normally included in annual consolidated financial statements have been condensed or omitted pursuant to the rules and regulations of the U.S. Securities and Exchange Commission. Because the interim unaudited consolidated financial statements do not include all of the information and notes required by GAAP for a complete set of consolidated financial statements, they should be read in conjunction with the audited consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the year ended January 28, 2018. The results reported in these interim unaudited consolidated financial statements should not be regarded as indicative of results that may be expected for any subsequent period or for the entire year.

The Company’s interim unaudited consolidated statements of income are referred to herein as the "Statements of Income." The Company’s interim unaudited consolidated balance sheets are referred to herein as the "Balance Sheets" and interim unaudited consolidated statements of cash flows as the "Statements of Cash Flows."

Segment Information

The Company’s Chief Executive Officer ("CEO") has been identified as the Chief Operating Decision Maker ("CODM") as defined by guidance regarding segment disclosures (see Note 13 for further discussion). Prior to the first quarter of fiscal year 2019, the Company had four operating segments. However as of April 29, 2018, the Company identified three operating segments that aggregate into one reportable segment, the Semiconductor Products Group.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make 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 period. Actual results could differ from those estimates.

Recent Accounting Standards Adopted

In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Accounting Standards Codification ("ASC") 606), which requires an entity to recognize revenue from the transfer of control of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance addresses, in particular, contracts with more than one performance obligation, as well as the accounting for some costs to obtain or fulfill a contract with a customer, and provides for additional disclosures with respect to revenues and cash flows arising from contracts with customers.

The Company adopted the standard, effective January 29, 2018, using the modified retrospective transition method which resulted in an adjustment to retained earnings for the cumulative effect of applying the standard to all contracts not completed as of the adoption date. The primary change associated with the adoption relates to the Company’s sales to distributors with return or price adjustment rights where the Company will no longer defer revenue until the resale by the distributor to the end customer, but rather, will record revenue at the time control transfers to the distributor. The Company estimated the effects of returns and allowances provided to these distributors. Upon adoption, including the effect of income taxes, opening retained earnings as of January 29, 2018 increased by $11.1 million net, as a result of these changes. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods.

In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Asset Transfers Other Than Inventory (Topic 740). This accounting standard update is aimed at recognizing the income tax consequences of intra-entity transfers of assets other than inventory when they occur. This removes the exception to postpone the recognition of income tax consequences of intra-entity transfers until the asset has been sold to an outside party. In the first quarter of 2019, the Company adopted ASU 2016-16 using a modified retrospective transition method, resulting in a $1.8 million decrease in retained earnings, a $3.7 million net increase in deferred income tax assets, and a $5.5 million decrease in pre-paid taxes.

Accounting Guidance Issued but Not Adopted as of April 29, 2018

In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815). This standard addresses narrow issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. Part I addresses the complexity of accounting for certain financial instruments with down round features. Part II addresses the difficulty of navigating Topic 480, Distinguishing Liabilities from Equity, because of the existence of pending content in the ASC that results from the indefinite deferral of accounting requirements concerning mandatorily redeemable financial instruments of certain non-public entities and certain mandatorily redeemable non-controlling interests. The new standard is effective for interim and annual fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company does not expect the adoption of this pronouncement to have a material impact on the Company’s consolidated financial statements.

In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815). The new standard is designed to refine and expand hedge accounting for both financial (e.g., interest rate) and commodity risks. Its provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the footnotes. It also makes certain targeted improvements to simplify the application of hedge accounting guidance. The new standard is effective for interim and annual fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption, including adoption in an interim period, is permitted. The Company is currently evaluating the impact this ASU will have on its consolidated condensed financial statements and disclosures.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will require that substantially all leases be recognized by lessees on their balance sheets as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The new standard also will result in enhanced quantitative and qualitative disclosures, including descriptions of significant judgments made by management, to provide greater insight into the extent of expense recognized and expected to be recognized from existing leases. The standard requires modified retrospective adoption and will be effective for the Company as of the beginning of fiscal year 2020. The Company expects the valuation of right of use assets and lease liabilities, previously described as operating leases, to be the present value of the Company's forecasted future lease commitments. The Company is continuing to assess the overall impacts of the new standard, including the discount rate to be applied in these valuations.