Background and Basis of Presentation	6 Months Ended
Jun. 29, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation	Note 1: Background and Basis of Presentation ON Semiconductor Corporation, together with its wholly-owned and majority-owned subsidiaries ("ON Semiconductor" or the "Company"), uses a thirteen-week fiscal quarter accounting period for the first three fiscal quarters of each year, with the second quarter of 2018 having ended on June 29, 2018, and each fiscal year ending on December 31. The quarters ended June 29, 2018 and June 30, 2017 each contained 91 days. The six months ended June 29, 2018 and June 30, 2017 contained 180 and 181 days, respectively. During the quarter ended June 29, 2018, the Company changed the name of one of its operating and reporting segments from Image Sensor Group to Intelligent Sensing Group. As of June 29, 2018, the Company was organized into the following three operating and reporting segments: the Power Solutions Group, the Analog Solutions Group and the Intelligent Sensing Group. Additional details on the Company’s operating and reporting segments are included in Note 2: ''Revenue and Segment Information.'' The accompanying unaudited financial statements as of and for the quarter and six months ended June 29, 2018 have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") for unaudited interim financial information. Accordingly, the unaudited financial statements do not include all of the information and footnotes required by GAAP for audited financial statements. The balance sheet as of December 31, 2017 was derived from the Company's audited financial statements but does not include all disclosures required by GAAP for audited financial statements. In the opinion of the Company's management, the interim information includes all adjustments, which includes normal recurring adjustments, necessary for a fair statement of the results for the interim periods. The footnote disclosures related to the interim financial information included herein are also unaudited. Such financial information should be read in conjunction with the consolidated financial statements and related notes thereto for the year ended December 31, 2017 included in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2017, which was filed with the SEC on February 21, 2018 (the “2017 Form 10-K”). Financial results for interim periods are not necessarily indicative of the results of operations that may be expected for a full fiscal year. Adoption of New Revenue Standard On January 1, 2018, as required, the Company adopted ASU No. 2014-09 - Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"), ASU No. 2015-14 - Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date ("ASU 2015-14"), ASU No. 2016-08 - Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations ("ASU 2016-08"), ASU No. 2016-10 - Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing ("ASU 2016-10"), ASU No. 2016-12 - Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients ("ASU 2016-12") and ASU No. 2016-20 - Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers” ("ASU 2016-20") (collectively “the New Revenue Standard”). To conform to the New Revenue Standard, the Company modified its revenue recognition policy as described below. Change in Accounting Policy On January 1, 2018, the Company adopted the New Revenue Standard using the modified retrospective method, applying the guidance to all open contracts and recognized the cumulative effect adjustment of $2.1 million to retained earnings and accrued expenses as of that date. The comparative financial information has not been restated and continues to be presented under the accounting standards in effect for the respective periods. The Company applied the practical expedient and has not disclosed the revenues allocated to future shipments of partially completed contracts. Substantially all of the Company’s revenues continue to be recognized following the transfer of control of the products to the customer, which typically occurs upon shipment or delivery depending on the terms of the underlying contracts. Under the New Revenue Standard, revenues from certain product development agreements, which were previously deferred as delivered, are now recognized over time. During the quarter and six months ended June 29, 2018, revenues increased by $1.0 million and $2.8 million, respectively, due to the impact of the adoption of the New Revenue Standard. Revenue Recognition Policy In anticipation of the adoption of the New Revenue Standard, during the quarter ended March 31, 2017, the Company developed its internal systems, processes and controls to enable it to make the estimates required by the New Revenue Standard on sales to its distributors and was able to reliably estimate upfront the effects of returns and allowances and record revenues at the time of shipments to these distributors. Prior to this, the Company recognized revenues from distributors under the sell-through method as it did not have the ability to estimate the effects of returns and allowances. As a result of this change, the Company recognized an additional $155.1 million in revenues during the first quarter of 2017, which resulted in an increase of $59.0 million to income before income taxes. The Company generates revenue from sales of its semiconductor products to OEMs, electronic manufacturing service providers and distributors. The Company also generates revenue, to a much lesser extent, from product development agreements and manufacturing services provided to customers. The Company recognizes revenue when it satisfies a performance obligation in an amount reflecting the consideration to which it expects to be entitled. For sales agreements, the Company has identified the promise to transfer products, each of which is distinct, to be the performance obligation. For product development agreements, the Company has identified the completion of a service defined in the agreement to be the performance obligation. The Company applies a five-step approach in determining the amount and timing of revenue to be recognized: (1) identifying the contract with a customer; (2) identifying the performance obligations in the contract; (3) determining the transaction price; (4) allocating the transaction price to the performance obligations in the contract; and (5) recognizing revenue when the performance obligation is satisfied. Substantially all of the Company’s revenue is recognized at the time control of the products transfers to the customer. Sales agreements with customers are renewable periodically and contain terms and conditions with respect to payment, delivery, warranty and supply, but typically do not require minimum purchase commitments. In the absence of a sales agreement, the Company’s standard terms and conditions apply. The Company considers the customer purchase orders, governed by sales agreements or the Company’s standard terms and conditions, to be the contract with the customer. The Company evaluates certain factors including the customer’s ability to pay (or credit risk). Most of the Company’s OEM customers negotiate pricing terms on an annual basis, while the electronic manufacturer service providers and distributors generally negotiate pricing terms on a quarterly basis. Pricing terms on product development agreements are negotiated at the beginning of a project. The Company allocates the transaction price to each distinct product based on its relative stand-alone selling price. In determining the transaction price, the Company evaluates whether the price is subject to refund or adjustment to determine the net consideration to which the Company expects to be entitled. The Company’s OEM customers do not have the right to return products, other than pursuant to the provisions of the Company’s standard warranty. Sales to distributors, however, are typically made pursuant to agreements that provide return rights with respect to discontinued or slow-moving products, referred to as stock rotation. Sales to distributors can also be subject to price adjustment on certain products, primarily for distributors with ship and credit rights. Although payment terms vary, most distributor agreements require payment within 30 days. In addition, the Company offers cash discounts to certain customers for payments received within an agreed upon time, generally 10 days after shipment. The Company recognizes revenue when it satisfies a performance obligation. The Company recognizes revenue from sales agreements upon transferring control of a product to the customer. This typically occurs when products are shipped or delivered, depending on the delivery terms, or when products that are consigned at customer locations are consumed. The Company recognizes revenue from product development agreements over time based on the cost-to-cost method. Revenues recognized during the quarter and six months ended June 29, 2018, for sales agreements was $1,447.9 million and $2,820.7 million, respectively, and for product development agreements was $8.0 million and $12.8 million, respectively. Sales returns and allowances are estimated based on historical experience. Provisions for discounts and rebates to customers, estimated returns and allowances, ship and credit claims and other adjustments are provided for in the same period the related revenues are recognized, and are netted against revenues. For returns, the Company recognizes a related asset for the right to recover returned products with a corresponding reduction to cost of goods sold. The Company reviews warranty and related claims activity and records provisions, as necessary. The Company records a reserve for cash discounts as a reduction to accounts receivable and a reduction to revenues, based on the experience with each customer. Frequently, the Company receives orders with multiple delivery dates that may extend across reporting periods. Since each delivery constitutes a performance obligation, the Company allocates the transaction price of the contract to each performance obligation based on the stand-alone selling price of the products. The Company invoices the customer for each delivery upon shipment and recognizes revenue in accordance with delivery terms. As scheduled delivery dates are within one year, revenue allocated to future shipments of partially completed contracts are not disclosed. The Company has elected to record freight and handling costs associated with outbound freight after control over a product has transferred to a customer as a fulfillment cost and include it in cost of revenues. Taxes assessed by government authorities on revenue-producing transactions, including value-added and excise taxes, are presented on a net basis (excluded from revenues) in the Consolidated Statements of Operations and Comprehensive Income. The Company generally warrants that products sold to its customers will, at the time of shipment, be free from defects in workmanship and materials and conform to specifications. The Company’s standard warranty extends for a period of two years from the date of delivery, except in the case of image sensor products, which are warrantied for one year from the date of delivery. At the time revenue is recognized, the Company establishes an accrual for estimated warranty expenses associated with its sales and records them as a component of the cost of revenues. Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amount of assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Management evaluates these estimates and judgments on an ongoing basis and bases its estimates on experience, current and expected future conditions, third-party evaluations and various other assumptions that management believes are reasonable under the circumstances. Significant estimates have been used by management in conjunction with the following: (i) estimates of future payouts for customer incentives and estimates of amounts subject to allowances, returns and warranties; (ii) measurement of valuation allowances relating to inventories and trade receivables; (iii) future cash flows used to assess and test for impairment of goodwill and indefinite-lived intangible assets and long-lived assets, if applicable; (iv) assumptions surrounding future pension obligations; (v) fair values of share-based compensation and of financial instruments (including derivative financial instruments); (vi) measurement of valuation allowances against deferred tax assets, evaluations of uncertain tax positions and the impact of U.S. tax reform; and (vii) estimates and assumptions used in connection with business combinations. Actual results may differ from the estimates and assumptions used in the consolidated financial statements and related notes. Foreign Currencies Most of the Company’s foreign subsidiaries conduct business primarily in U.S. dollars and, as a result, utilize the dollar as their functional currency. For the remeasurement of financial statements of these subsidiaries, assets and liabilities in foreign currencies that are receivable or payable in cash are remeasured at current exchange rates, while inventories and other non-monetary assets in foreign currencies are remeasured at historical rates. Gains and losses resulting from the remeasurement of such financial statements are included in the operating results, as are gains and losses incurred on foreign currency transactions. Historically, the majority of the Company’s Japanese subsidiaries utilized Japanese Yen as their functional currency. The assets and liabilities of these subsidiaries are translated at current exchange rates, while revenues and expenses are translated at the average rates in effect for the period. The related translation gains and losses are included in other comprehensive income or loss within the Consolidated Statements of Operations and Comprehensive Income. As a result of an analysis which took into account the economic indicators of these subsidiaries from a long-term perspective, the Company changed the functional currency for some of these subsidiaries from Japanese Yen to U.S. dollars effective as of January 1, 2018.

Note 1: Background and Basis of Presentation

ON Semiconductor Corporation, together with its wholly-owned and majority-owned subsidiaries ("ON Semiconductor" or the "Company"), uses a thirteen-week fiscal quarter accounting period for the first three fiscal quarters of each year, with the second quarter of 2018 having ended on June 29, 2018, and each fiscal year ending on December 31. The quarters ended June 29, 2018 and June 30, 2017 each contained 91 days. The six months ended June 29, 2018 and June 30, 2017 contained 180 and 181 days, respectively. During the quarter ended June 29, 2018, the Company changed the name of one of its operating and reporting segments from Image Sensor Group to Intelligent Sensing Group. As of June 29, 2018, the Company was organized into the following three operating and reporting segments: the Power Solutions Group, the Analog Solutions Group and the Intelligent Sensing Group. Additional details on the Company’s operating and reporting segments are included in Note 2: ''Revenue and Segment Information.''

The accompanying unaudited financial statements as of and for the quarter and six months ended June 29, 2018 have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") for unaudited interim financial information. Accordingly, the unaudited financial statements do not include all of the information and footnotes required by GAAP for audited financial statements. The balance sheet as of December 31, 2017 was derived from the Company's audited financial statements but does not include all disclosures required by GAAP for audited financial statements. In the opinion of the Company's management, the interim information includes all adjustments, which includes normal recurring adjustments, necessary for a fair statement of the results for the interim periods. The footnote disclosures related to the interim financial information included herein are also unaudited. Such financial information should be read in conjunction with the consolidated financial statements and related notes thereto for the year ended December 31, 2017 included in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2017, which was filed with the SEC on February 21, 2018 (the “2017 Form 10-K”). Financial results for interim periods are not necessarily indicative of the results of operations that may be expected for a full fiscal year.

Adoption of New Revenue Standard

On January 1, 2018, as required, the Company adopted ASU No. 2014-09 - Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"), ASU No. 2015-14 - Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date ("ASU 2015-14"), ASU No. 2016-08 - Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations ("ASU 2016-08"), ASU No. 2016-10 - Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing ("ASU 2016-10"), ASU No. 2016-12 - Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients ("ASU 2016-12") and ASU No. 2016-20 - Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers” ("ASU 2016-20") (collectively “the New Revenue Standard”). To conform to the New Revenue Standard, the Company modified its revenue recognition policy as described below.

Change in Accounting Policy

On January 1, 2018, the Company adopted the New Revenue Standard using the modified retrospective method, applying the guidance to all open contracts and recognized the cumulative effect adjustment of $2.1 million to retained earnings and accrued expenses as of that date. The comparative financial information has not been restated and continues to be presented under the accounting standards in effect for the respective periods. The Company applied the practical expedient and has not disclosed the revenues allocated to future shipments of partially completed contracts.

Substantially all of the Company’s revenues continue to be recognized following the transfer of control of the products to the customer, which typically occurs upon shipment or delivery depending on the terms of the underlying contracts. Under the New Revenue Standard, revenues from certain product development agreements, which were previously deferred as delivered, are now recognized over time.

During the quarter and six months ended June 29, 2018, revenues increased by $1.0 million and $2.8 million, respectively, due to the impact of the adoption of the New Revenue Standard.

Revenue Recognition Policy

In anticipation of the adoption of the New Revenue Standard, during the quarter ended March 31, 2017, the Company developed its internal systems, processes and controls to enable it to make the estimates required by the New Revenue Standard on sales to its distributors and was able to reliably estimate upfront the effects of returns and allowances and record revenues at the time of shipments to these distributors. Prior to this, the Company recognized revenues from distributors under the sell-through method as it did not have the ability to estimate the effects of returns and allowances. As a result of this change, the Company recognized an additional $155.1 million in revenues during the first quarter of 2017, which resulted in an increase of $59.0 million to income before income taxes.

The Company generates revenue from sales of its semiconductor products to OEMs, electronic manufacturing service providers and distributors. The Company also generates revenue, to a much lesser extent, from product development agreements and manufacturing services provided to customers. The Company recognizes revenue when it satisfies a performance obligation in an amount reflecting the consideration to which it expects to be entitled. For sales agreements, the Company has identified the promise to transfer products, each of which is distinct, to be the performance obligation. For product development agreements, the Company has identified the completion of a service defined in the agreement to be the performance obligation. The Company applies a five-step approach in determining the amount and timing of revenue to be recognized: (1) identifying the contract with a customer; (2) identifying the performance obligations in the contract; (3) determining the transaction price; (4) allocating the transaction price to the performance obligations in the contract; and (5) recognizing revenue when the performance obligation is satisfied. Substantially all of the Company’s revenue is recognized at the time control of the products transfers to the customer.

Sales agreements with customers are renewable periodically and contain terms and conditions with respect to payment, delivery, warranty and supply, but typically do not require minimum purchase commitments. In the absence of a sales agreement, the Company’s standard terms and conditions apply. The Company considers the customer purchase orders, governed by sales agreements or the Company’s standard terms and conditions, to be the contract with the customer. The Company evaluates certain factors including the customer’s ability to pay (or credit risk).

Most of the Company’s OEM customers negotiate pricing terms on an annual basis, while the electronic manufacturer service providers and distributors generally negotiate pricing terms on a quarterly basis. Pricing terms on product development agreements are negotiated at the beginning of a project. The Company allocates the transaction price to each distinct product based on its relative stand-alone selling price.

In determining the transaction price, the Company evaluates whether the price is subject to refund or adjustment to determine the net consideration to which the Company expects to be entitled. The Company’s OEM customers do not have the right to return products, other than pursuant to the provisions of the Company’s standard warranty. Sales to distributors, however, are typically made pursuant to agreements that provide return rights with respect to discontinued or slow-moving products, referred to as stock rotation. Sales to distributors can also be subject to price adjustment on certain products, primarily for distributors with ship and credit rights. Although payment terms vary, most distributor agreements require payment within 30 days. In addition, the Company offers cash discounts to certain customers for payments received within an agreed upon time, generally 10 days after shipment.

The Company recognizes revenue when it satisfies a performance obligation. The Company recognizes revenue from sales agreements upon transferring control of a product to the customer. This typically occurs when products are shipped or delivered, depending on the delivery terms, or when products that are consigned at customer locations are consumed. The Company recognizes revenue from product development agreements over time based on the cost-to-cost method. Revenues recognized during the quarter and six months ended June 29, 2018, for sales agreements was $1,447.9 million and $2,820.7 million, respectively, and for product development agreements was $8.0 million and $12.8 million, respectively. Sales returns and allowances are estimated based on historical experience. Provisions for discounts and rebates to customers, estimated returns and allowances, ship and credit claims and other adjustments are provided for in the same period the related revenues are recognized, and are netted against revenues. For returns, the Company recognizes a related asset for the right to recover returned products with a corresponding reduction to cost of goods sold. The Company reviews warranty and related claims activity and records provisions, as necessary. The Company records a reserve for cash discounts as a reduction to accounts receivable and a reduction to revenues, based on the experience with each customer.

Frequently, the Company receives orders with multiple delivery dates that may extend across reporting periods. Since each delivery constitutes a performance obligation, the Company allocates the transaction price of the contract to each performance obligation based on the stand-alone selling price of the products. The Company invoices the customer for each delivery upon shipment and recognizes revenue in accordance with delivery terms. As scheduled delivery dates are within one year, revenue allocated to future shipments of partially completed contracts are not disclosed.

The Company has elected to record freight and handling costs associated with outbound freight after control over a product has transferred to a customer as a fulfillment cost and include it in cost of revenues. Taxes assessed by government authorities on revenue-producing transactions, including value-added and excise taxes, are presented on a net basis (excluded from revenues) in the Consolidated Statements of Operations and Comprehensive Income.

The Company generally warrants that products sold to its customers will, at the time of shipment, be free from defects in workmanship and materials and conform to specifications. The Company’s standard warranty extends for a period of two years from the date of delivery, except in the case of image sensor products, which are warrantied for one year from the date of delivery. At the time revenue is recognized, the Company establishes an accrual for estimated warranty expenses associated with its sales and records them as a component of the cost of revenues.

Use of Estimates

The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amount of assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Management evaluates these estimates and judgments on an ongoing basis and bases its estimates on experience, current and expected future conditions, third-party evaluations and various other assumptions that management believes are reasonable under the circumstances. Significant estimates have been used by management in conjunction with the following: (i) estimates of future payouts for customer incentives and estimates of amounts subject to allowances, returns and warranties; (ii) measurement of valuation allowances relating to inventories and trade receivables; (iii) future cash flows used to assess and test for impairment of goodwill and indefinite-lived intangible assets and long-lived assets, if applicable; (iv) assumptions surrounding future pension obligations; (v) fair values of share-based compensation and of financial instruments (including derivative financial instruments); (vi) measurement of valuation allowances against deferred tax assets, evaluations of uncertain tax positions and the impact of U.S. tax reform; and (vii) estimates and assumptions used in connection with business combinations. Actual results may differ from the estimates and assumptions used in the consolidated financial statements and related notes.

Foreign Currencies

Most of the Company’s foreign subsidiaries conduct business primarily in U.S. dollars and, as a result, utilize the dollar as their functional currency. For the remeasurement of financial statements of these subsidiaries, assets and liabilities in foreign currencies that are receivable or payable in cash are remeasured at current exchange rates, while inventories and other non-monetary assets in foreign currencies are remeasured at historical rates. Gains and losses resulting from the remeasurement of such financial statements are included in the operating results, as are gains and losses incurred on foreign currency transactions.

Historically, the majority of the Company’s Japanese subsidiaries utilized Japanese Yen as their functional currency. The assets and liabilities of these subsidiaries are translated at current exchange rates, while revenues and expenses are translated at the average rates in effect for the period. The related translation gains and losses are included in other comprehensive income or loss within the Consolidated Statements of Operations and Comprehensive Income. As a result of an analysis which took into account the economic indicators of these subsidiaries from a long-term perspective, the Company changed the functional currency for some of these subsidiaries from Japanese Yen to U.S. dollars effective as of January 1, 2018.