ON Semiconductor (ON) 10-Q 30 Oct 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Oct. 02, 2015	Oct. 28, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	ON Semiconductor Corporation
Entity Central Index Key	1,097,864
Current Fiscal Year End	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Oct. 2, 2015
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2,015
Amendment Flag	false
Entity Common Stock, Shares Outstanding		412,702,059

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents	$ 556.8	$ 511.7
Short-term investments	0.8	6.1
Receivables, net	505.9	417.5
Inventories	754	729.9
Other current assets	135.2	140.6
Total current assets	1,952.7	1,805.8
Property, plant and equipment, net	1,256.1	1,203.9
Goodwill	271.3	263.8
Intangible assets, net	360.1	458.5
Other assets	109.9	91
Total assets	3,950.1	3,823
Liabilities and Stockholders’ Equity
Accounts payable	361.9	378.2
Accrued expenses	306.4	287.9
Deferred income on sales to distributors	130.4	165.1
Current portion of long-term debt (See Note 7)	539.3	209.6
Total current liabilities	1,338	1,040.8
Long-term debt (See Note 7)	868.4	983
Other long-term liabilities	162.6	151.8
Total liabilities	$ 2,369	$ 2,175.6
Commitments and contingencies (See Note 10)
ON Semiconductor Corporation stockholders’ equity:
Common stock ($0.01 par value, 750,000,000 shares authorized, 532,553,825 and 524,615,562 shares issued, 412,573,664 and 434,100,017 shares outstanding, respectively)	$ 5.3	$ 5.2
Additional paid-in capital	3,404	3,281.2
Accumulated other comprehensive loss	(44.1)	(41.5)
Accumulated deficit	(763.5)	(915.6)
Less: Treasury stock, at cost: 119,980,161 and 90,515,545 shares, respectively	(1,043.4)	(702.8)
Total ON Semiconductor Corporation stockholders’ equity	1,558.3	1,626.5
Non-controlling interest in consolidated subsidiary	22.8	20.9
Total stockholders' equity	1,581.1	1,647.4
Total liabilities and equity	$ 3,950.1	$ 3,823

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - $ / shares	Oct. 02, 2015	Dec. 31, 2014
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock, shares issued (in shares)	532,553,825	524,615,562
Common stock, shares outstanding (in shares)	412,573,664	434,100,017
Treasury stock, shares (in shares)	119,980,161	90,515,545

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Income Statement [Abstract]
Revenues	$ 904.2	$ 833.5	$ 2,655.5	$ 2,297.6
Cost of revenues (exclusive of amortization shown below)	595.7	552.6	1,742.2	1,490.4
Gross profit	308.5	280.9	913.3	807.2
Operating expenses:
Research and development	104.9	93.4	305.7	255.7
Selling and marketing	52.3	51.1	156	143.4
General and administrative	44.9	48.5	136.6	134.2
Amortization of acquisition-related intangible assets	33.6	21	101.1	39.6
Restructuring, asset impairments and other, net	3.3	10.1	4.5	20
Goodwill and intangible asset impairment	0.1	0	3.8	0
Total operating expenses	239.1	224.1	707.7	592.9
Operating income	69.4	56.8	205.6	214.3
Other (expense) income, net:
Interest expense	(14.9)	(8.6)	(34.8)	(24.6)
Interest income	0.2	0.2	0.8	0.6
Other	2.1	(1.2)	7.9	(2.1)
Loss on debt extinguishment	0	0	(0.4)	0
Other (expense) income, net	(12.6)	(9.6)	(26.5)	(26.1)
Income before income taxes	56.8	47.2	179.1	188.2
Income tax (provision) benefit	(10)	(6.3)	(25.1)	3.7
Net income	46.8	40.9	154	191.9
Less: Net income attributable to non-controlling interest	(0.5)	(0.4)	(1.9)	(1.6)
Net income attributable to ON Semiconductor Corporation	46.3	40.5	152.1	190.3
Comprehensive income (loss), net of tax:
Net income	46.8	40.9	154	191.9
Foreign currency translation adjustments	0.2	1.9	0.2	1.3
Effects of cash flow hedges	0.4	(1.2)	1.7	1.5
Effects of available-for-sale securities	(1.1)	0	(4.5)	0
Other comprehensive (loss) income, net of tax of $0.0 million	(0.5)	0.7	(2.6)	2.8
Comprehensive income	46.3	41.6	151.4	194.7
Comprehensive income attributable to non-controlling interest	(0.5)	(0.4)	(1.9)	(1.6)
Comprehensive income attributable to ON Semiconductor Corporation	$ 45.8	$ 41.2	$ 149.5	$ 193.1
Net income per common share attributable to ON Semiconductor Corporation:
Basic (in dollars per share)	$ 0.11	$ 0.09	$ 0.36	$ 0.43
Diluted (in dollars per share)	$ 0.11	$ 0.09	$ 0.35	$ 0.43
Weighted-average common shares outstanding:
Basic (in shares)	413.7	440.7	424	440.7
Diluted (in shares)	417.5	444.9	431.3	444.6

Consolidated Statements of Ope5

Consolidated Statements of Operations and Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Income Statement [Abstract]
Other comprehensive (loss) income, tax	$ 0	$ 0	$ 0	$ 0

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014
Cash flows from operating activities:
Net income	$ 154	$ 191.9
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	267.8	182.4
Gain on sale or disposal of fixed assets	(4.1)	(0.6)
Loss on debt extinguishment	0.4	0
Amortization of debt issuance costs	1.9	1
Write-down of excess inventories	38.4	21.1
Non-cash share-based compensation expense	36.3	33
Non-cash interest	11.2	5.1
Non-cash asset impairment charges	0.2	1.8
Non-cash goodwill and intangible asset impairment charges	3.8	0
Change in deferred taxes	0.1	(16.7)
Other	(5.5)	0.6
Changes in assets and liabilities (exclusive of the impact of acquisitions):
Receivables	(87.6)	(46.5)
Inventories	(62.1)	(29.4)
Other assets	(15.4)	(13.4)
Accounts payable	(11.8)	11.2
Accrued expenses	19.4	(25.6)
Deferred income on sales to distributors	(34.7)	26.5
Other long-term liabilities	1.1	(23.6)
Net cash provided by operating activities	313.4	318.8
Cash flows from investing activities:
Purchases of property, plant and equipment	(204.8)	(163)
Proceeds from sales of property, plant and equipment	10.4	0.3
Deposits utilized for purchases of property, plant and equipment	0.2	2
Purchase of businesses, net of cash acquired	(10.1)	(423.1)
Cash placed in escrow	(0.8)	(40)
Proceeds from sale of available-for-sale securities	5.5	0
Proceeds from sale of held-to-maturity securities	2	116.2
Purchases of held-to-maturity securities	(0.8)	(2.8)
Net cash used in investing activities	(198.4)	(510.4)
Cash flows from financing activities:
Proceeds from issuance of common stock under the employee stock purchase plan	10.9	4.8
Proceeds from exercise of stock options	25.1	20.4
Payments of tax withholding for restricted shares	(12.4)	(6)
Repurchase of common stock	(328.2)	(53.7)
Proceeds from debt issuance	808.1	307.5
Purchases of convertible note hedges	(108.9)	0
Proceeds from issuance of warrants	52	0
Payments of debt issuance and other financing costs	(20.4)	0
Repayment of long-term debt	(478.4)	(63.3)
Payment of capital lease obligations	(17.5)	(31.6)
Dividend to non-controlling shareholder of consolidated subsidiary	0	(2.7)
Net cash (used in) provided by financing activities	(69.7)	175.4
Effect of exchange rate changes on cash and cash equivalents	(0.2)	(1.2)
Net increase (decrease) in cash and cash equivalents	45.1	(17.4)
Cash and cash equivalents, beginning of period	511.7	509.5
Cash and cash equivalents, end of period	$ 556.8	$ 492.1

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Oct. 02, 2015
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 third quarter of 2015 ending on October 2, 2015 , and each fiscal year ending on December 31. The three months ended October 2, 2015 and September 26, 2014 both contained 91 days. The nine months ended October 2, 2015 and September 26, 2014 contained 275 and 269 days, respectively. As of October 2, 2015 , the Company was organized into four operating segments, which also represent its four reporting segments: Application Products Group, Image Sensor Group, Standard Products Group, and System Solutions Group. Additional details on the Company's reportable segments are included in Note 15: “Segment Information.” The accompanying unaudited financial statements as of and for the quarter and nine months ended October 2, 2015 have been prepared in accordance with generally accepted accounting principles in the United States of America for unaudited interim financial information. Accordingly, the unaudited financial statements do not include all of the information and footnotes required by generally accepted accounting principles in the United States of America for audited financial statements. The balance sheet as of December 31, 2014 was derived from the Company's audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America for audited financial statements. In the opinion of the Company's management, the interim information includes all adjustments, which consist of 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, 2014 included in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2014 , filed with the Commission on February 27, 2015 (“2014 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. The Company expanded or condensed certain prior year amounts in the Company's unaudited consolidated financial statements to conform to the current year presentation. Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles in the United States of America 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. Significant estimates have been used by management in conjunction with the following: (i) measurement of valuation allowances relating to trade receivables, inventories and deferred tax assets; (ii) estimates of future payouts for customer incentives and allowances, warranties, and restructuring activities; (iii) assumptions surrounding future pension obligations; (iv) fair values of share-based compensation and of financial instruments (including derivative financial instruments); (v) evaluations of uncertain tax positions; (vi) estimates and assumptions used in connection with business combinations; and (vii) future cash flows used to assess and test for impairment of goodwill and long-lived assets, if applicable. Actual results could differ from these estimates. Retrospective Measurement Period Adjustments for Business Combinations During the quarter ended April 3, 2015, the Company finalized the purchase price allocation of Aptina and, as a result, retrospectively adjusted its Consolidated Balance Sheet and related information as of December 31, 2014 for an immaterial amount as follows (in millions, see Note 3: ''Acquisitions'' for additional information): As of December 31, 2014 As Reported Revision As Revised Goodwill $ 264.7 $ (0.9 ) $ 263.8 Intangible assets, net $ 457.6 $ 0.9 $ 458.5 During the quarter ended December 31, 2014, the Company finalized the purchase price allocation of Truesense and, as a result, retrospectively adjusted its consolidated statements of operations and comprehensive income with respect to the amortization of acquisition-related intangible assets for the quarter and nine months ended September 26, 2014 as disclosed in the 2014 Form 10-K. The impact of these measurement period adjustments are included in the amounts shown below under the heading " Revision of Previously-Issued Financial Statements." Revision of Previously-Issued Financial Statements As disclosed in the 2014 Form 10-K, the Company identified errors in its financial statements for the first three quarters of the fiscal year ended December 31, 2014, as included in the Company's 2014 quarterly reports on Form 10-Q, and revised its previously issued financial statements to record a deferred tax asset in a foreign subsidiary during a prior period and to make adjustments in each successive period related to the foreign currency exchange rate changes associated with that item. The interim period ended September 26, 2014 also includes revised amounts from a change in the application of an accounting convention related to manufacturing variances. The Company assessed the effect of the above errors in the aggregate on prior periods’ financial statements in accordance with the Commission’s Staff Accounting Bulletins No. 99 and 108 and, based on an analysis of quantitative and qualitative factors, determined that the errors were not material to any of the Company’s prior interim and annual financial statements. The financial statements for the quarter and nine months ended September 26, 2014 included in this Form 10-Q are revised as described below for those adjustments and should be read in conjunction with Item 8, “Financial Statements and Supplementary Data” disclosed in the 2014 Form 10-K. All financial information contained in the accompanying notes to these unaudited consolidated financial statements has been revised to reflect the correction of these errors. The following tables present the effect of the aforementioned revisions and adjustments on the Company’s consolidated statements of operations and comprehensive income for the quarter and nine months ended September 26, 2014 (in millions, except per share data): Quarter Ended September 26, 2014 As Reported Revision (1) As Revised Cost of revenues (exclusive of amortization shown below) $ 549.4 $ 3.2 $ 552.6 Gross profit 284.1 (3.2 ) 280.9 Operating expenses: Amortization of acquisition-related intangible assets (1) 23.4 (2.4 ) 21.0 Operating income 57.6 (0.8 ) 56.8 Other (0.9 ) (0.3 ) (1.2 ) Other (expenses) income, net (9.3 ) (0.3 ) (9.6 ) Income before income taxes 48.3 (1.1 ) 47.2 Net income 42.0 (1.1 ) 40.9 Net income attributable to ON Semiconductor Corporation 41.6 (1.1 ) 40.5 Comprehensive income 42.7 (1.1 ) 41.6 Comprehensive income attributable to ON Semiconductor Corporation 42.3 (1.1 ) 41.2 Nine Months Ended September 26, 2014 As Reported Revision (1) As Revised Cost of revenues (exclusive of amortization shown below) $ 1,489.7 $ 0.7 $ 1,490.4 Gross profit 807.9 (0.7 ) 807.2 Operating expenses: Amortization of acquisition-related intangible assets (1) 42.0 (2.4 ) 39.6 Operating income 212.6 1.7 214.3 Other (2.7 ) 0.6 (2.1 ) Other (expenses) income, net (26.7 ) 0.6 (26.1 ) Income before income taxes 185.9 2.3 188.2 Net income 189.6 2.3 191.9 Net income attributable to ON Semiconductor Corporation 188.0 2.3 190.3 Comprehensive income 192.4 2.3 194.7 Comprehensive income attributable to ON Semiconductor Corporation 190.8 2.3 193.1 Diluted net income per common share attributable to ON Semiconductor Corporation $ 0.42 0.01 $ 0.43 (1) Includes the business combination measurement period adjustment of $2.4 million with respect to the amortization of acquisition-related intangible assets for the quarter and nine months ended September 26, 2014 in accordance with the final purchase price allocation of Truesense as discussed above. The following tables present the effect of the aforementioned revisions and adjustments on the Company’s consolidated statement of cash flows for the nine months ended September 26, 2014 (in millions). There was no impact to total cash flows from operating activities as a result of the revisions and adjustments: Nine months ended September 26, 2014 As Reported Revision (1) As Revised Cash flows from operating activities: Net income $ 189.6 $ 2.3 $ 191.9 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization (1) 184.8 (2.4 ) 182.4 Change in deferred taxes (16.1 ) (0.6 ) (16.7 ) Changes in assets and liabilities (exclusive of the impact of acquisitions): Inventories (30.1 ) 0.7 (29.4 ) (1) Includes the business combination measurement period adjustment of $2.4 million with respect to the amortization of acquisition-related intangible assets for the quarter and nine months ended September 26, 2014 in accordance with the final purchase price allocation of Truesense as discussed above.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Oct. 02, 2015
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Note 2: Recent Accounting Pronouncements ASU No. 2015-16 - "Simplifying the Accounting for Measurement-Period Adjustments" ("ASU 2015-16") In September 2015, the FASB issued ASU 2015-16, which requires that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amendment also requires that the acquirer record, in the same period’s financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The amendments in ASU 2015-16 also require an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods as if the adjustment to the provisional amounts had been recognized as of the acquisition date. The amendments are effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The amendments in ASU 2015-16 will be applied prospectively to adjustments to provisional amounts that occur after the effective date of ASU 2015-16, with earlier application permitted for financial statements that have not been issued. The Company has not elected early adoption as of the period ended October 2, 2015. ASU No. 2015-11 - "Simplifying the Measurement of Inventory" ("ASU 2015-11") In July 2015, the FASB issued ASU 2015-11, which requires that an entity should measure in-scope inventory at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The amendments are effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact that the adoption of ASU 2015-11 may have on its consolidated financial statements and has not elected early adoption as of the period ended October 2, 2015. ASU 2015-05 - “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement” ("ASU 2015-05") In April 2015, the FASB issued ASU 2015-05, which provides guidance regarding the accounting for fees paid by a customer in cloud computing arrangements. If a cloud computing arrangement includes a software license, then the customer would account for the payment of fees as an acquisition of software. If there is no software license, the payment of fees would be accounted for as a service contract. This ASU is effective in fiscal years beginning after December 15, 2015. An entity can elect to adopt the amendments either prospectively for all arrangements entered into or materially modified after the effective date, or retrospectively. Early adoption is permitted. The Company is currently evaluating the impact that the adoption of ASU 2015-05 may have on its consolidated financial statements and has not elected early adoption as of the period ended October 2, 2015. ASU No. 2015-03 - "Simplifying the Presentation of Debt Issuance Costs" ("ASU 2015-03") In April 2015, the FASB issued ASU 2015-03, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The new standard is effective for fiscal years beginning after December 15, 2015 and interim periods within those fiscal years. Early adoption is permitted for financial statements that have not been previously issued. The Company has not elected early adoption as of the period ended October 2, 2015 . As of October 2, 2015 , debt issuance costs of $19.7 million were recorded as assets on the Company's Consolidated Balance Sheet. ASU No. 2014-09 - “Revenue from Contracts with Customers (Topic 606)” (“ASU 2014-09”) and ASU No. 2015-14 - "Deferral of the Effective Date" ("ASU 2015-14") In May 2014, the FASB issued ASU 2014-09, which applies to any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets, unless those contracts are within the scope of other standards, superceding the revenue recognition requirements in Topic 605. Pursuant to ASU 2014-09, an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange, as applied through a multi-step process to achieve that core principle. Subsequently, the FASB approved a deferral included in ASU 2015-14 that permits public entities to apply the amendments in ASU 2014-09 for annual reporting periods beginning after December 15, 2017, including interim reporting periods therein, and that would also permit public entities to elect to adopt the amendments as of the original effective date as applicable to reporting periods beginning after December 15, 2016. The Company is currently evaluating the impact that the adoption of ASU 2014-09 and ASU 2015-14 may have on its consolidated financial statements as of the period ended October 2, 2015. As described in the 2014 Form 10-K, the Company defers the revenue and cost of revenues on sales to certain distributors until it is informed by the distributor that the distributor has resold the products to the end customer. Upon adoption of ASU 2014-09 and 2015-14, a portion of this deferred income amount may be recognized upon shipment to the distributor rather than upon sale to the end customer. The balance of deferred income on sales to distributors included on the Company's Consolidated Balance Sheet as of October 2, 2015 and December 31, 2014 , was $130.4 million and $165.1 million , respectively.

Acquisitions

Acquisitions	9 Months Ended
	Oct. 02, 2015
Business Combinations [Abstract]
Acquisitions	Note 3: Acquisitions Acquisition of Aptina On August 15, 2014, the Company acquired 100% of Aptina for $405.4 million in cash, of which the $2.9 million that remained unpaid as of December 31, 2014 was subsequently paid during the nine months ended October 2, 2015 . As discussed below, $40.0 million of the total consideration was held in escrow as of October 2, 2015 . The allocation of the purchase price of Aptina was finalized during the quarter ended April 3, 2015 . Aptina is incorporated into the Company's Image Sensor Group for reporting purposes. The following table presents the initial allocation and subsequent adjustments applied on a retrospective basis to the purchase price of Aptina for the assets acquired and liabilities assumed on August 15, 2014 based on their fair values (in millions): Initial Estimate Adjustments Final Allocation Cash and cash equivalents $ 30.3 $ — $ 30.3 Receivables 53.2 — 53.2 Inventories 85.3 (0.5 ) 84.8 Other current assets 5.7 — 5.7 Property, plant and equipment 35.9 0.4 36.3 Goodwill 63.8 0.6 64.4 Intangible assets 183.1 24.7 207.8 In-process research and development 75.4 (24.1 ) 51.3 Other non-current assets 2.3 — 2.3 Total assets acquired 535.0 1.1 536.1 Accounts payable 66.8 (0.2 ) 66.6 Other current liabilities 51.2 (1.5 ) 49.7 Other non-current liabilities 14.5 (0.1 ) 14.4 Total liabilities assumed 132.5 (1.8 ) 130.7 Net assets acquired $ 402.5 $ 2.9 $ 405.4 Acquired intangible assets include $51.3 million of IPRD assets, which are to be amortized over their respective useful lives upon successful completion of the related projects. The value assigned to IPRD was determined by considering the importance of products under development to the overall development plan, reviewing costs incurred for the projects, estimating costs to develop the purchased IPRD into commercially viable products, estimating the resulting net cash flows from the projects when completed and discounting the net cash flows to their present value. Other acquired intangible assets of $207.8 million include: customer relationships of $126.5 million ( two to six year useful life); developed technology of $79.0 million ( six year useful life); and trademarks of $2.3 million ( six month useful life). Goodwill of $64.4 million was assigned to the Image Sensor Group. Among the factors that contributed to goodwill arising from the acquisition were the potential synergies that are expected to be derived from combining Aptina with the Company’s existing image sensor business. Goodwill is not deductible for tax purposes. Pursuant to the agreement and plan of merger between the Company and the sellers of Aptina (the "Merger Agreement"), $40.0 million of the total consideration was withheld by the Company and is placed into an escrow account through November 2015 to secure against certain indemnifiable events described in the Merger Agreement. The $40.0 million consideration held in escrow has been accounted for as restricted cash as of October 2, 2015 and is included in other current assets and accrued expenses on the Company’s Consolidated Balance Sheet as of October 2, 2015 . Acquisition of Truesense On April 30, 2014, the Company acquired 100% of Truesense for $95.7 million in cash. Truesense is incorporated into the Company's Image Sensor Group and the allocation of the purchase price was finalized during the year ended December 31, 2014. Acquisition of AXSEM On July 15, 2015 (the "Acquisition Date"), the Company acquired 100% of AXSEM for $8.0 million in cash consideration, plus an additional unlimited contingent consideration (the "Earn-out") with a fair value of $5.0 million as of the Acquisition Date. The unlimited Earn-out payment, if any, is based on the achievement of certain revenue targets during two separate measurement periods consisting of the following: (i) the period from the first day of the Company's third fiscal quarter of 2016 to the last day of the Company's second fiscal quarter of 2017; and (ii) the period from the first day of the Company's third fiscal quarter of 2017 to the last day of the Company's second fiscal quarter of 2018. Pursuant to the terms of the Share Purchase Agreement, $0.8 million of cash consideration was held in escrow and is included on the Company's Consolidated Balance Sheet as of October 2, 2015 to secure against certain indemnifiable events in connection with the acquisition of AXSEM. AXSEM is incorporated into the Company's Application Product Group for reporting purposes. The acquisition of AXSEM expands the Company's industrial and timing business and is another step forward in expanding the Company's presence in select segments of the industrial end-market. The estimated Earn-out fair value of $5.0 million , measured at Level 3, was included in non-current liabilities on the Company's Consolidated Balance Sheet as of October 2, 2015 . The initial allocation of $13.0 million of acquired net assets is included in the Company's balance sheet as of the Acquisition Date. The initial estimated purchase price allocation is subject to change as the Company finalizes its determination relating to the valuation of net assets acquired from AXSEM, including IPRD and other intangible assets. Accordingly, future adjustments may impact the initial estimated amount of goodwill and other allocated amounts. See Note 4: ''Goodwill and Intangible Assets'' for a discussion of the goodwill and intangible assets related to the AXSEM acquisition. Goodwill is not deductible for tax purposes. Pro-forma Results of Operations The following unaudited pro-forma consolidated results of operations for the quarter and nine months ended September 26, 2014 has been prepared as if the acquisitions of Aptina and Truesense had occurred on January 1, 2013 and includes adjustments for depreciation expense, amortization of intangibles, and the effect of purchase accounting adjustments including the step-up of inventory (in millions, except per share data): Quarter Ended Nine Months Ended September 26, 2014 September 26, 2014 Revenues $ 906.1 $ 2,672.2 Gross profit 308.5 924.3 Net income attributable to ON Semiconductor Corporation $ 22.4 $ 128.2 Net income per common share attributable to ON Semiconductor Corporation: Basic $ 0.05 $ 0.29 Diluted $ 0.05 $ 0.29 The Company has determined that pro-forma results for the ASXEM acquisition are not significant for disclosure.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Oct. 02, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Note 4: Goodwill and Intangible Assets Goodwill The following table summarizes goodwill by relevant reportable segment as of October 2, 2015 and December 31, 2014 (in millions): Balance as of October 2, 2015 Balance as of December 31, 2014 Goodwill Accumulated Impairment Losses Carrying Value Goodwill Accumulated Impairment Losses Carrying Value Reportable Segment: Application Products Group $ 547.4 $ (418.9 ) $ 128.5 $ 539.9 $ (418.9 ) $ 121.0 Image Sensor Group 95.4 — 95.4 95.4 — 95.4 Standard Products Group 76.0 (28.6 ) 47.4 76.0 (28.6 ) 47.4 $ 718.8 $ (447.5 ) $ 271.3 $ 711.3 $ (447.5 ) $ 263.8 Goodwill is tested for impairment annually on the first day of the fourth quarter unless a triggering event would require an interim analysis. Adverse changes in operating results and/or unfavorable changes in economic factors used to estimate fair values may result in future non-cash impairment charges. While management did not identify any triggering events through October 2, 2015 that would require an interim impairment analysis, the Company's current projections include assumptions of current industry and market conditions, which could negatively change, and in turn, may adversely impact the fair value of the Company's goodwill, intangible assets and other long-lived assets. As a result, the carrying value of the reporting units containing the Company's goodwill may exceed their fair value in future impairment tests. The increase of $7.5 million in goodwill is attributable to the AXSEM acquisition. See Note 3: ''Acquisitions'' for additional information. Intangible Assets Intangible assets, net, were as follows as of October 2, 2015 and December 31, 2014 (in millions): October 2, 2015 Original Cost Accumulated Amortization Foreign Currency Translation Adjustment Accumulated Impairment Losses Carrying Value Intellectual property $ 13.9 $ (10.5 ) $ — $ (0.4 ) $ 3.0 Customer relationships 426.2 (197.0 ) (27.8 ) (23.7 ) 177.7 Patents 43.7 (23.0 ) — (13.7 ) 7.0 Developed technology 246.6 (135.7 ) — (2.6 ) 108.3 Trademarks 16.3 (9.8 ) — (1.1 ) 5.4 Backlog 0.3 (0.2 ) — — 0.1 IPRD 62.4 — — (3.8 ) 58.6 Total intangibles $ 809.4 $ (376.2 ) $ (27.8 ) $ (45.3 ) $ 360.1 December 31, 2014 Original Cost Accumulated Amortization Foreign Currency Translation Adjustment Accumulated Impairment Losses Carrying Value Intellectual property $ 13.9 $ (10.0 ) $ — $ (0.4 ) $ 3.5 Customer relationships 425.6 (146.2 ) (27.8 ) (23.7 ) 227.9 Patents 43.7 (21.3 ) — (13.7 ) 8.7 Developed technology 241.9 (88.9 ) — (2.6 ) 150.4 Trademarks 16.3 (8.7 ) — (1.1 ) 6.5 IPRD 61.5 — — — 61.5 Total intangibles $ 802.9 $ (275.1 ) $ (27.8 ) $ (41.5 ) $ 458.5 During the quarter and nine months ended October 2, 2015 , the Company canceled certain of its previously capitalized IPRD projects and recorded impairment losses of $0.1 million and $3.8 million , respectively, included in the “Goodwill and intangible asset impairment” caption on the Company's Consolidated Statements of Operations and Comprehensive Income. Additionally, during the nine months ended October 2, 2015 , the Company completed certain of its IPRD projects, resulting in the reclassification of $3.4 million to developed technology, and acquired $6.5 million of intangibles from the acquisition of AXSEM and resulting purchase accounting. See Note 3: ''Acquisitions'' for additional information. Amortization expense for acquisition-related intangible assets amounted to $ 33.6 million and $101.1 million for the quarter and nine months ended October 2, 2015 , respectively, and $21.0 million and $39.6 million for the quarter and nine months ended September 26, 2014 , respectively. Amortization expense for intangible assets, with the exception of the $58.6 million of IPRD assets that will be amortized once the corresponding projects have been completed, is expected to be as follows for each of the next five years and thereafter (in millions): Period Estimated Amortization Expense Remainder of 2015 $ 34.0 2016 89.1 2017 57.3 2018 35.5 2019 29.9 Thereafter 55.7 Total estimated amortization expense $ 301.5

Restructuring, Asset Impairment

Restructuring, Asset Impairments and Other, Net	9 Months Ended
	Oct. 02, 2015
Restructuring Charges [Abstract]
Restructuring, Asset Impairments and Other, Net	Note 5: Restructuring, Asset Impairments and Other, Net Summarized activity included in the “Restructuring, asset impairments and other, net” caption on the Company's Consolidated Statements of Operations and Comprehensive Income for the quarter and nine months ended October 2, 2015 is as follows (in millions): Restructuring Impairment Other Total Quarter ended October 2, 2015 Business combination severance $ 0.2 $ — $ — $ 0.2 General Workforce Reductions 1.2 — — 1.2 Other (1) 0.3 — 1.6 1.9 Total $ 1.7 $ — $ 1.6 $ 3.3 Restructuring Impairment Other Total Nine months ended October 2, 2015 KSS facility closure $ 0.3 $ — $ (3.4 ) $ (3.1 ) Business combination severance 0.9 — — 0.9 General Workforce Reductions 1.2 — — 1.2 European marketing organization relocation 3.5 — — 3.5 Other (1) 0.5 0.2 1.3 2.0 Total $ 6.4 $ 0.2 $ (2.1 ) $ 4.5 (1) Includes amounts related to certain reductions in workforce, other facility closures, asset disposal activity and certain other activity which is not considered to be significant. Changes in accrued restructuring charges from December 31, 2014 to October 2, 2015 are summarized as follows (in millions): Balance as of December 31, 2014 Charges Usage Balance as of Estimated employee separation charges $ 2.3 $ 6.4 $ (4.0 ) $ 4.7 Estimated costs to exit 1.1 — (0.6 ) 0.5 Total $ 3.4 $ 6.4 $ (4.6 ) $ 5.2 Activity related to the Company’s restructuring programs that were either initiated during 2015 or had not been completed as of October 2, 2015 , is as follows: KSS Facility Closure On October 6, 2013, the Company announced a plan to close KSS (the "KSS Plan"). Pursuant to the KSS Plan, a majority of the production from KSS was transferred to other Company manufacturing facilities. The KSS Plan includes the elimination of 170 full time and 40 contract employees. There were no charges incurred during the quarter ended October 2, 2015 . For the nine months ended October 2, 2015 , t he Company recorded $0.3 million of employee related separation charges, offset by $3.4 million of gains related to the sale of assets. All of the employees have exited under this program, and there was no remaining accrual for future payments as of October 2, 2015 . Business Combination Severance Certain positions were eliminated following the acquisition of Aptina on August 15, 2014. During the first quarter of 2015, 44 positions were identified for elimination. The Company recorded $0.2 million and $0.9 million of related employee separation charges during the quarter and nine months ended October 2, 2015 , respectively. The total plan is estimated to cost $1.2 million . The remaining 12 employees are expected to exit during the fourth quarter of 2015. As of October 2, 2015 , there was a $0.3 million accrued liability associated with employee separation charges. European Marketing Organization Relocation In January 2015, the Company announced that it would relocate its European customer marketing organization from France to Slovakia and Germany. As a result, six positions are expected to be eliminated. The Company recorded $3.5 million of related employee separation charges during the nine months ended October 2, 2015 . There were no charges incurred during the quarter ended October 2, 2015 . The total plan is estimated to incur $3.5 million of expenses. The impacted employees are expected to exit during the second half of 2016. As of October 2, 2015 , there was a $3.3 million accrued liability associated with employee separation charges for the European customer marketing organization move. General Workforce Reductions During the third quarter of 2015, management approved and commenced implementation of restructuring actions, primarily targeted workforce reductions. As of October 2, 2015 , the Company had notified 43 employees of their employment termination, approximately half of which had exited during the third quarter of 2015 and the remaining employees are expected to exit by December 31, 2015. The total expense for the quarter ended October 2, 2015 was $1.2 million . The Company paid $0.7 million during the quarter ended October 2, 2015 and had an accrual of $0.5 million at October 2, 2015 . Subsequent to October 2, 2015 , the Company identified an additional 90 - 100 positions subject to termination. The Company expects to incur approximately $4.0 million to $5.0 million of additional charges during the fourth quarter of 2015 associated with the termination of those positions. All exits are expected to be completed by December 31, 2015.

Balance Sheet Information

Balance Sheet Information	9 Months Ended
	Oct. 02, 2015
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Information	Note 6: Balance Sheet Information Certain amounts included in the Company's balance sheet as of October 2, 2015 and December 31, 2014 consist of the following (dollars in millions): October 2, 2015 December 31, 2014 Receivables, net: Accounts receivable $ 509.1 $ 419.1 Less: Allowance for doubtful accounts (3.2 ) (1.6 ) $ 505.9 $ 417.5 Inventories: Raw materials $ 90.7 $ 119.7 Work in process 465.1 365.5 Finished goods 198.2 244.7 $ 754.0 $ 729.9 Other current assets: Prepaid expenses $ 34.0 $ 28.7 Value added and other income tax receivables 42.2 40.4 Acquisition consideration held in escrow (see Note 3) 40.8 40.0 Other (1) 18.2 31.5 $ 135.2 $ 140.6 Property, plant and equipment, net: Land $ 46.2 $ 46.1 Buildings 505.1 484.3 Machinery and equipment 2,314.7 2,165.0 Total property, plant and equipment 2,866.0 2,695.4 Less: Accumulated depreciation (1,609.9 ) (1,491.5 ) $ 1,256.1 $ 1,203.9 Accrued expenses: Accrued payroll $ 100.1 $ 117.0 Sales related reserves 82.8 65.8 Acquisition consideration payable to seller (see Note 3) 40.8 40.0 Other 82.7 65.1 $ 306.4 $ 287.9 (1) Included in other current assets are $0.8 million of property, plant and equipment which are held-for-sale as of October 2, 2015 . Warranty Reserves Activity related to the Company's warranty reserves for the nine months ended October 2, 2015 and September 26, 2014 is as follows (in millions): Nine Months Ended October 2, 2015 September 26, 2014 Beginning Balance $ 5.5 $ 6.0 Provision 2.0 2.0 Usage (1.5 ) (2.3 ) Ending Balance $ 6.0 $ 5.7 Defined Benefit Plans The Company maintains defined benefit plans for certain of its foreign subsidiaries. The Company recognizes the aggregate amount of all overfunded plans as assets and the aggregate amount of all underfunded plans as liabilities in its financial statements. As of October 2, 2015 , the total accrued pension liability for underfunded plans was $ 94.1 million , of which the current portion of $ 0.1 million was classified as accrued expenses. As of December 31, 2014 , the total accrued pension liability for underfunded plans was $ 96.1 million , of which the current portion of $ 0.2 million was classified as accrued expenses. The components of the Company's net periodic pension expense for the quarters and nine months ended October 2, 2015 and September 26, 2014 are as follows (in millions): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Service cost $ 2.1 $ 2.2 $ 6.5 $ 7.1 Interest cost 0.9 1.3 2.9 4.3 Expected return on plan assets (0.9 ) (0.9 ) (2.7 ) (2.7 ) Curtailment gain — (0.6 ) — (6.5 ) Total net periodic pension cost $ 2.1 $ 2.0 $ 6.7 $ 2.2

Long-Term Debt

Long-Term Debt	9 Months Ended
	Oct. 02, 2015
Debt Disclosure [Abstract]
Long-Term Debt	Note 7: Long-Term Debt The Company's long-term debt consists of the following (annualized rates, dollars in millions): October 2, 2015 December 31, 2014 Senior Revolving Credit Facility due 2020, interest payable monthly at 1.69% as of $ — $ 350.0 1.00% Notes (net of discount of $104.7 million) (1) 585.3 — 2.625% Notes, Series B (net of discount of $9.2 million and $14.7 million, respectively) (2) 347.7 342.2 Loan with Japanese bank due 2015 through 2018, interest payable quarterly at 2.08% and 2.01%, respectively (3) 198.2 235.9 U.S. real estate mortgages payable monthly through 2019 at an average rate of 3.35% (4) 51.2 54.8 Loans with Philippine bank due 2015 through 2019, interest payable monthly and quarterly at an average rate of 2.49% and 2.37%, respectively (5) 28.0 54.2 Loan with Hong Kong bank, interest payable weekly at 1.44% and 1.92%, respectively (6) 25.0 35.0 Malaysia revolving line of credit, interest payable quarterly at 1.78% and 1.71%, respectively (7) 25.0 25.0 Loan with Singapore bank, interest payable weekly at 1.44% and 1.42%, respectively (6) 30.0 20.0 Vietnam revolving line of credit, interest payable quarterly and annually at an average rate of 1.79% and 1.87%, respectively (7) 22.4 10.7 Canada revolving line of credit, interest payable quarterly at 1.92% and 1.84%, respectively (7) 15.0 15.0 Loans with Philippine bank due 2016 through 2020, interest payable at 2.29% (8) 50.0 — Canada equipment financing payable monthly through 2017 at 3.81% (8) 2.8 4.2 U.S. equipment financing payable monthly through 2016 at 2.40% and 2.94%, respectively (8) 1.7 4.8 Capital lease obligations 25.4 40.8 Long-term debt, including current maturities 1,407.7 1,192.6 Less: Current maturities (539.3 ) (209.6 ) Long-term debt $ 868.4 $ 983.0 _______________________ (1) Interest is payable on June 1 and December 1 of each year at 1.00% annually. See below under the heading " 1.00% Notes " for additional information. (2) Interest is payable on June 15 and December 15 of each year at 2.625% annually. The 2.625% Notes, Series B may be put back to the Company at the option of the holders of the notes on December 15 of 2016 and 2021 or called at the option of the Company on or after December 20, 2016. The notes can be converted at any time on or after June 15, 2016. (3) This loan represents SCI LLC's non-collateralized loan with SMBC, which is guaranteed by the Company. (4) Debt arrangement collateralized by real estate, including certain of the Company's facilities in California, Oregon and Idaho. (5) $28.0 million collateralized by equipment as of October 2, 2015 with $15.0 million non-collateralized and $39.2 million collateralized by equipment as of December 31, 2014 . (6) Debt arrangement collateralized by accounts receivable. (7) Non-collateralized debt arrangement . (8) Debt arrangement collateralized by equipment. Expected maturities relating to the Company’s long-term debt as of October 2, 2015 are as follows (in millions): Period Expected Maturities Remainder of 2015 $ 133.0 2016 433.0 2017 65.5 2018 144.6 2019 46.7 Thereafter 698.8 Total $ 1,521.6 For purposes of the table above, the 2.625% Notes, Series B are assumed to mature at the earliest conversion date. For additional information with respect to the Company's long-term debt, see Note 8: "Long-Term Debt" of the notes to the Company's audited consolidated financial statements included in Part IV, Item 15 of the 2014 Form 10-K. Amended Senior Revolving Credit Facility On May 1, 2015 , the Company and its wholly-owned subsidiary, SCI LLC, entered into an amendment to the $800.0 million , five -year senior revolving credit facility (the “Facility”) Amended and Restated Credit Agreement dated as of October 10, 2013 (“Credit Agreement”) among the Company and a group of lenders. The amendment expands the borrowing capacity of the Facility to $1.0 billion and resets the five-year maturity date. The Facility may be used for general corporate purposes including working capital, stock repurchase, and/or acquisitions. The Company recorded $2.1 million of new debt issuance costs and wrote-off $0.4 million of existing debt issuance costs associated with the Facility resulting in a loss on debt extinguishment during the nine months ended October 2, 2015 . On June 1, 2015, the Company and its wholly-owned subsidiary, SCI LLC, entered into a second amendment of the Facility that provides for, among other things, modifications to the Facility to allow for the issuance by the Company of its convertible senior notes, subject to the satisfaction of certain conditions, and to permit the Company to enter into certain hedging transactions relating to such notes or otherwise. In addition, the second amendment provides for the release of the pledged stock of certain of the Company’s subsidiaries upon the issuance of the convertible senior notes. The obligations under the Facility are guaranteed by certain of the domestic subsidiaries of the Company and SCI LLC. 1.00% Notes On June 8, 2015, the Company completed a private placement of $690.0 million of its 1.00% Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended. The Company was the sole issuer in the private unregistered offering of the 1.00% Notes. The Company incurred issuance costs of $18.3 million in connection with the issuance of the notes, of which $15.4 million were capitalized as debt issuance costs and are being amortized using the effective interest method and $2.9 million were allocated to the conversion option (as further described below) and were recorded to equity. The 1.00% Notes are governed by an indenture between the Company, as the issuer, and Wells Fargo Bank, National Association, as trustee. The Company's use of the net proceeds from the offering included the following: (i) the funding of the cost of the convertible note hedge transactions described below (the cost of which was partially offset by the proceeds that the Company received from entering into the warrant transactions described below); (ii) funding the repurchase of $70.0 million of the Company's common stock which was acquired from purchasers of the 1.00% Notes in privately negotiated transactions effected through one or more of the initial purchasers or their affiliates conducted concurrently with the issuance of the 1.00% Notes ; and (iii) repayment of $350.0 million of borrowings outstanding under its revolving credit facility. The remainder of the proceeds is intended for general corporate purposes, including additional share repurchases and potential acquisitions. The notes bear interest at the rate of 1.00% per year from the date of issuance, payable semiannually in arrears on June 1 and December 1 of each year, beginning on December 1, 2015 . The notes are fully and unconditionally guaranteed on a senior unsecured obligation basis by certain existing domestic subsidiaries of the Company. The notes are convertible by holders into cash and shares of the Company’s common stock at a conversion rate of 54.0643 shares of common stock per $1,000 principal amount of notes (subject to adjustment in certain events), which is equivalent to an initial conversion price of $18.50 per share of common stock. The Company will settle conversion of all notes validly tendered for conversion in cash and shares of the Company’s common stock, if applicable, subject to the Company’s right to pay the share amount in additional cash. Holders may convert their notes only under the following circumstances: (i) during any calendar quarter commencing after the calendar quarter ending on September 30, 2015, if the last reported sale price of common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (ii) during the five business-day period immediately following any five consecutive trading-day period in which the trading price per $1,000 principal amount of notes for each day of such period was less than 98% of the product of the closing sale price of the Company’s common stock and the conversion rate; (iii) upon occurrence of the specified transactions described in the indenture relating to the notes; or (iv) on and after September 1, 2020 . Upon conversion of the notes, the Company will deliver cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company's election. For a discussion of the dilutive effects for earnings per share calculations, see Note 8: "Earnings Per Share and Equity." The notes will mature on December 1, 2020 . If a holder elects to convert its notes in connection with the occurrence of specified fundamental changes that occur prior to September 1, 2020 , the holder will be entitled to receive, in addition to cash and shares of common stock equal to the conversion rate, an additional number of shares of common stock, in each case as described in the indenture. Notwithstanding these conversion rate adjustments, these notes contain an explicit limit on the number of shares issuable upon conversion. In connection with the occurrence of specified fundamental changes, holders may require the Company to repurchase for cash all or part of their notes at a purchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but not including, the fundamental change repurchase date. The notes, which are the Company’s unsecured obligations, will rank equally in right of payment to all of the Company’s existing and future unsubordinated indebtedness and will be senior in right of payment to all of the Company’s existing and future subordinated obligations. The notes will also be effectively subordinated to any of the Company’s or its subsidiaries’ secured indebtedness to the extent of the value of the assets securing such indebtedness. In accordance with accounting guidance on embedded conversion features, the Company valued and bifurcated the conversion option associated with the 1.00% Notes from the respective host debt instrument, which is referred to as the debt discount, and initially recorded the conversion option of $110.4 million in stockholders' equity. The resulting debt discount is being amortized to interest expense at an effective interest rate of 4.29% over the contractual terms of the notes. Included in other assets as of October 2, 2015 , were $14.6 million of debt issuance costs associated with the 1.00% Notes, which are being amortized using the effective interest method. Included in long-term debt as of October 2, 2015 was $104.7 million of unamortized debt discount associated with the 1.00% Notes , which will be amortized using the effective interest method. The Company used $56.9 million of the net proceeds from the offering of its 1.00% Notes to concurrently enter into convertible note hedge and warrant transactions with certain of the initial purchasers of the 1.00% Notes . Pursuant to these transactions, the Company has the option to purchase initially (subject to adjustment for certain specified transactions) a total of 37.3 million shares of its common stock at a price of $18.50 per share. The total cost of the convertible note hedge transactions was $108.9 million . In addition, the Company sold warrants to certain bank counterparties whereby the holders of the warrants have the option to purchase initially (subject to adjustment for certain specified events) a total of 37.3 million shares of the Company's common stock at a price of $25.96 per share. The Company received $52.0 million in cash proceeds from the sale of these warrants. In aggregate, the purchase of the convertible note hedges and the sale of the warrants are intended to offset potential dilution from the conversion of these notes. As these transactions meet certain accounting criteria, the convertible note hedges and warrants are recorded in stockholders' equity and are not accounted for as derivatives. The net cost incurred in connection with the convertible note hedge and warrant transactions was recorded as a reduction to additional paid in capital in the Consolidated Balance Sheet. A portion of the shares subject to the conversion of the 1.00% Notes and hedging transactions were reserved in the form of the Company's treasury stock. Philippine Term Loans During the second quarter of 2015, the Company's wholly-owned Philippine subsidiaries and ON Semiconductor, as guarantor, entered into two non-collateralized term loans with an aggregate borrowing capacity of $50.0 million , the terms of which were set forth in agreements by and between the Company’s Philippine subsidiaries and a Philippine bank. During the third quarter of 2015, the Company borrowed the full $50.0 million available under the term loans. Borrowings under the loans bear interest based on 3-month LIBOR plus 2.0% per annum, with interest payable quarterly in arrears. The total borrowed amount must be repaid within five years over 17 equal quarterly principal installments starting at the end of the fourth quarter from the initial drawdown date.

Earnings per Share and Equity

Earnings per Share and Equity	9 Months Ended
	Oct. 02, 2015
Earnings Per Share [Abstract]
Earnings Per Share and Equity	Note 8: Earnings Per Share and Equity Earnings Per Share Calculations of net income per common share attributable to ON Semiconductor are as follows (in millions, except per share data): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Net income attributable to ON Semiconductor Corporation $ 46.3 $ 40.5 $ 152.1 $ 190.3 Basic weighted average common shares outstanding 413.7 440.7 424.0 440.7 Dilutive effect of share-based awards 3.8 4.2 4.7 3.9 Dilutive effect of Convertible Notes — — 2.6 — Diluted weighted average common shares outstanding 417.5 444.9 431.3 444.6 Net income per common share attributable to ON Semiconductor Corporation: Basic $ 0.11 $ 0.09 $ 0.36 $ 0.43 Diluted $ 0.11 $ 0.09 $ 0.35 $ 0.43 Basic net income per common share is computed by dividing net income attributable to ON Semiconductor Corporation by the weighted average number of common shares outstanding during the period. The number of incremental shares from the assumed exercise of stock options and assumed issuance of shares relating to restricted stock units is calculated by applying the treasury stock method. Share-based awards whose impact is considered to be anti-dilutive under the treasury stock method were excluded from the diluted net income per share calculation. The excluded number of anti-dilutive share-based awards was 2.2 million and 3.8 million for the quarters ended October 2, 2015 and September 26, 2014 , respectively, and 1.5 million and 6.2 million for the nine months ended October 2, 2015 and September 26, 2014 , respectively. The dilutive impact related to the Company's 1.00% Notes and 2.625% Notes, Series B is determined in accordance with the net share settlement requirements prescribed by ASC Topic 260, Earnings Per Share . Under the net share settlement calculation, the Company's convertible notes are assumed to be convertible into cash up to the par value, with the excess of par value being convertible into common stock. A dilutive effect occurs when the stock price exceeds the conversion price for each of the convertible notes. In periods when the share price is lower than the conversion price, the impact is anti-dilutive and therefore has no impact on the Company's earnings per share calculations. Additionally, if the average price of the Company's common stock exceeds $25.96 per share for a reporting period, the Company will also include the effect of the additional potential shares, using the treasury stock method, that may be issued related to the warrants that were issued concurrently with the issuance of the 1.00% Notes. Prior to conversion, the convertible note hedges are not considered for purposes of the earnings per share calculations, as their effect would be anti-dilutive. Upon conversion, the convertible note hedges are expected to offset the dilutive effect of the 1.00% Notes when the stock price is above $18.50 per share. See Note 8: "Long-Term Debt" of the notes to the Company's audited Consolidated Financial Statements included in Part IV, Item 15 of the 2014 Form 10-K for a discussion of the conversion prices and other features of the 2.625% Notes, Series B and see Note 7: ''Long-Term Debt'' for a discussion of the conversion prices and other features of the 1.00% Notes . Equity Share Repurchase Program Information relating to the Company's share repurchase programs is as follows (in millions, except per share data): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Number of repurchased shares (1)(5) 9.4 2.6 28.4 5.9 Beginning accrued share repurchases (2) $ 3.0 $ — $ — $ 0.6 Aggregate purchase price 100.1 24.2 328.2 54.4 Less: ending accrued share repurchases (3) — (1.3 ) — (1.3 ) Total cash used for share repurchases $ 103.1 $ 22.9 $ 328.2 $ 53.7 Weighted-average purchase price per share (4) $ 10.64 $ 9.23 $ 11.53 $ 9.25 Available for future purchases at period end $ 648.2 $ 89.0 $ 648.2 $ 89.0 (1) None of these shares had been reissued or retired as of October 2, 2015 , but may be reissued or retired by the Company at a later date. (2) Represents unpaid amounts recorded in accrued expenses on the Company's Consolidated Balance Sheet as of the beginning of the period. (3) Represents unpaid amounts recorded in accrued expenses on the Company's Consolidated Balance Sheet as of the end of the period. (4) Exclusive of fees, commissions and other expenses. (5) Includes 5.4 million shares in the nine month period, totaling $70.0 million , repurchased concurrently with the issuance of the 1.00% Notes. See Note 7: ''Long-Term Debt'' for information with respect to the Company's long-term debt. Shares for Restricted Stock Units Tax Withholding Treasury stock is recorded at cost and is presented as a reduction of stockholders' equity in the accompanying unaudited consolidated financial statements. Shares, with a fair market value equal to the applicable statutory minimum amount of the employee withholding taxes due, are withheld by the Company upon the vesting of restricted stock units to pay the applicable statutory minimum amount of employee withholding taxes and are considered common stock repurchases. The Company then pays the applicable statutory minimum amount of withholding taxes in cash. The amount remitted for the quarter and nine months ended October 2, 2015 was $ 1.0 million and $12.4 million , respectively, for which the Company withheld 0.1 million and 1.0 million shares of common stock, respectively, that were underlying the restricted stock units that vested. None of these shares had been reissued or retired as of October 2, 2015 ; however, these shares may be reissued or retired by the Company at a later date. Non-Controlling Interest The Company's entity which operates assembly and test operations in Leshan, China is owned by a joint venture company, Leshan-Phoenix Semiconductor Company Limited (“Leshan”). The Company owns a majority of the outstanding equity interests in Leshan and its investment in Leshan has been consolidated in the Company's financial statements. At December 31, 2014 , the non-controlling interest balance was $ 20.9 million . This balance increased to $22.8 million as of October 2, 2015 , resulting from the non-controlling interest's $1.9 million share of the earnings for the nine months ended October 2, 2015 . At December 31, 2013 , the non-controlling interest balance was $32.8 million . This balance was $31.7 million as of September 26, 2014 due to the non-controlling interest's $1.6 million share of the earnings for the nine months ended September 26, 2014 , offset by a $2.7 million dividend paid to the non-controlling shareholder.

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Oct. 02, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Note 9: Share-Based Compensation Total share-based compensation expense related to the Company's employee stock options, restricted stock units, stock grant awards and ESPP for the quarters and nine months ended October 2, 2015 and September 26, 2014 was comprised as follows (in millions): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Cost of revenues $ 2.0 $ 1.7 $ 5.8 $ 4.8 Research and development 2.2 2.2 7.0 6.2 Selling and marketing 2.2 2.1 6.7 5.8 General and administrative 4.5 5.1 16.8 16.2 Share-based compensation expense before income taxes $ 10.9 $ 11.1 $ 36.3 $ 33.0 Related income tax benefits (1) — — — — Share-based compensation expense, net of taxes $ 10.9 $ 11.1 $ 36.3 $ 33.0 ____________________ (1) A majority of the Company’s share-based compensation relates to its domestic subsidiaries; therefore, no related deferred income tax benefits are recorded due to historical net operating losses at those subsidiaries. As of October 2, 2015 , total estimated unrecognized share-based compensation expense, net of estimated forfeitures, related to non-vested stock options granted prior to that date was $ 1.1 million , which is expected to be recognized over a weighted-average period of 0.7 years. As of October 2, 2015 , total estimated unrecognized share-based compensation expense, net of estimated forfeitures, related to non-vested restricted stock units with time-based service conditions and performance-based vesting criteria granted prior to that date was $ 50.9 million , which is expected to be recognized over a weighted-average period of 1.6 years. The total intrinsic value of stock options exercised during the quarter and nine months ended October 2, 2015 was $ 0.5 million and $12.2 million , respectively. The Company recorded cash received from the exercise of stock options of $1.4 million and $25.1 million , respectively, during the quarter and nine months ended October 2, 2015 . The Company recorded no related income tax benefits during the quarter and nine months ended October 2, 2015 . Share-Based Compensation Information Share-based compensation expense recognized in the Consolidated Statements of Operations and Comprehensive Income is based on awards that are ultimately expected to vest. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The annualized pre-vesting forfeiture rate for stock options was estimated to be 11% and 11% during the quarters and nine months ended October 2, 2015 and September 26, 2014 , respectively. The annualized pre-vesting forfeiture rate for restricted stock units was estimated to be 5% and 5% during the quarters and nine months ended October 2, 2015 and September 26, 2014 , respectively. Shares Available As of December 31, 2014 , there was an aggregate of 35.2 million shares of common stock available for grant under the Company's Amended and Restated SIP and 3.0 million shares available for issuance under the ESPP. On May 20, 2015, shareholders approved an amendment to the Company’s ESPP which increased the number of shares reserved and available to be issued pursuant to the ESPP by 5.5 million . As of October 2, 2015 , there was an aggregate of 29.7 million shares of common stock available for grant under the Amended and Restated SIP and 7.2 million shares available for issuance under the ESPP. Stock Options Summarized stock option information for the nine months ended October 2, 2015 is as follows (in millions except per share and term data): Nine Months Ended October 2, 2015 Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (In-The-Money) Outstanding at December 31, 2014 8.8 $ 7.81 Granted — — Exercised (3.2 ) 7.84 Canceled (0.1 ) 7.02 Outstanding at October 2, 2015 5.5 $ 7.81 2.55 $ 10.0 Exercisable at October 2, 2015 4.9 $ 7.89 2.40 $ 8.5 Additional information with respect to stock options outstanding as of October 2, 2015 , with exercise prices less than or above $ 9.53 per share, the effective closing price of the Company's common stock at October 2, 2015 , is as follows (number of shares in millions): Exercisable Unexercisable Total Exercise Prices Number of Shares Weighted-Average Exercise Price Number of Shares Weighted-Average Exercise Price Number of Shares Weighted-Average Exercise Price Less than $9.53 4.4 $ 7.59 0.6 $ 7.17 5.0 $ 7.54 Above $9.53 0.5 $ 10.47 — $ — 0.5 $ 10.47 Total outstanding 4.9 $ 7.89 0.6 $ 7.17 5.5 $ 7.81 Restricted Stock Units Restricted stock units generally vest over three years with service-based requirements or performance-based requirements or a combination of service-based and performance-based requirements and are payable in shares of the Company's common stock upon vesting. The following table presents summarized information with respect to the Company's restricted stock units as of October 2, 2015 and changes during the nine months ended October 2, 2015 (number of shares in millions): Number of Shares Weighted-Average Grant Date Fair Value Non-vested shares underlying restricted stock units at December 31, 2014 8.7 $ 8.66 Granted 3.1 12.89 Achieved 0.7 9.35 Released (3.3 ) 8.73 Forfeited (0.4 ) 9.25 Non-vested shares underlying restricted stock units at October 2, 2015 8.8 $ 10.15 Stock Grant Awards During the nine months ended October 2, 2015 , the Company granted 0.1 million shares of stock under stock grant awards to certain directors of the Company with immediate vesting at a weighted-average grant date fair value of $12.50 per share.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Oct. 02, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 10: Commitments and Contingencies Leases The following represents future minimum lease obligations under non-cancelable operating leases as of October 2, 2015 (in millions): Remainder of 2015 $ 6.5 2016 21.4 2017 16.5 2018 11.7 2019 9.2 Thereafter 32.8 Total $ 98.1 Environmental Contingencies The Company’s headquarters in Phoenix, Arizona is located on property that is a “Superfund” site, which is a property listed on the National Priorities List and subject to clean-up activities under the Comprehensive Environmental Response, Compensation, and Liability Act. Motorola and Freescale have been involved in the clean-up of on-site solvent contaminated soil and groundwater and off-site contaminated groundwater pursuant to consent decrees with the State of Arizona. As part of the Company's August 4, 1999 recapitalization (the "Recapitalization"), Motorola retained responsibility for this contamination, and Motorola and Freescale have agreed to indemnify the Company with respect to remediation costs and other costs or liabilities related to this matter. As part of the Recapitalization, the Company received various manufacturing facilities, one of which is located in the Czech Republic. The Company has ongoing remediation projects at this site to respond to releases of hazardous substances that occurred prior to the Recapitalization during the years that this facility was operated by government-owned entities. In each case, the remediation project consists primarily of monitoring groundwater wells located on-site and off-site with additional action plans developed to respond in the event activity levels are exceeded at each of the respective locations. The government of the Czech Republic has agreed to indemnify the Company and the respective subsidiaries, subject to specified limitations, for remediation costs associated with this historical contamination. Based upon the information available, total future remediation costs to the Company are not expected to be material. The Company’s design center in East Greenwich, Rhode Island is located on property that has localized soil contamination. In connection with the purchase of the facility, the Company entered into a settlement agreement and covenant not to sue with the State of Rhode Island. This agreement requires that remedial actions be undertaken and a quarterly groundwater monitoring program be initiated by the former owners of the property. Based on the information available, any costs to the Company in connection with this matter have not been, and are not expected to be, material. As a result of its acquisition of AMIS, the Company is a "primary responsible party" to an environmental remediation and clean-up at AMIS's former corporate headquarters in Santa Clara, California. Costs incurred by AMIS have included implementation of the clean-up plan, operations and maintenance of remediation systems, and other project management costs. However, AMIS's former parent company, a subsidiary of Nippon Mining, contractually agreed to indemnify AMIS and the Company for any obligations relating to environmental remediation and clean-up at this location. Based on the information available, any costs to the Company in connection with this matter have not been, and are not expected to be, material. The Company's former manufacturing location in Aizu, Japan is located on property where soil and ground water contamination has been detected. The Company believes that the contamination originally occurred during a time when the facility was operated by a prior owner. The Company has worked with local authorities to implement a remediation plan and expects remaining remediation costs to be covered by insurance. Based on information available, any costs to the Company in connection with this matter have not been, and are not expected to be, material. The Company was notified by the Environmental Protection Agency (“EPA”) that it has been identified as a “potentially responsible party” (“PRP”) in the Chemetco Superfund matter. Chemetco is a defunct reclamation services supplier who operated in Illinois at what is now a Superfund site. The Company used Chemetco for reclamation services. The EPA is pursuing Chemetco customers for contribution to the site cleanup activities. The Company has joined a PRP group which is cooperating with the EPA in the evaluation and funding of the cleanup. Based on the information available, any costs to the Company in connection with this matter have not been, and are not expected to be, material. Financing Contingencies In the normal course of business, the Company provides standby letters of credit or other guarantee instruments to certain parties initiated by either the Company or its subsidiaries, as required for transactions such as, but not limited to, purchase commitments, agreements to mitigate collection risk, leases, utilities or customs guarantees. As of October 2, 2015 , the Company's senior revolving credit facility included $ 15.0 million of availability for the issuance of letters of credit. A $ 0.2 million letter of credit was outstanding under the senior revolving credit facility as of October 2, 2015 . The Company also had outstanding guarantees and letters of credit outside of its senior revolving credit facility totaling $4.8 million as of October 2, 2015 . As part of obtaining financing in the normal course of business, the Company issued guarantees related to certain of its capital lease obligations, equipment financing, lines of credit and real estate mortgages, which totaled $169.2 million as of October 2, 2015 . The Company is also a guarantor of SCI LLC's non-collateralized loan with SMBC, which had a balance of $198.2 million as of October 2, 2015 . See Note 7: ''Long-Term Debt'' for additional information. Based on historical experience and information currently available, the Company believes that it will not be required to make payments under the standby letters of credit or guarantee arrangements for the foreseeable future. Indemnification Contingencies The Company is a party to a variety of agreements entered into in the ordinary course of business pursuant to which it may be obligated to indemnify the other parties for certain liabilities that arise out of or relate to the subject matter of the agreements. Some of the agreements entered into by the Company require it to indemnify the other party against losses due to IP infringement, property damage including environmental contamination, personal injury, failure to comply with applicable laws, the Company’s negligence or willful misconduct, or breach of representations and warranties and covenants related to such matters as title to sold assets. The Company faces risk of exposure to warranty and product liability claims in the event that its products fail to perform as expected or such failure of its products results, or is alleged to result, in economic damage, bodily injury or property damage. In addition, if any of the Company’s designed products are alleged to be defective, the Company may be required to participate in their recall. Depending on the significance of any particular customer and other relevant factors, the Company may agree to provide more favorable rights to such customer for valid defective product claims. The Company and its subsidiaries provide for indemnification of directors, officers and other persons in accordance with limited liability agreements, certificates of incorporation, by-laws, articles of association or similar organizational documents, as the case may be. The Company maintains directors’ and officers’ insurance, which should enable it to recover a portion of any future amounts paid. While the Company’s future obligations under certain agreements may contain limitations on liability for indemnification, other agreements do not contain such limitations and under such agreements it is not possible to predict the maximum potential amount of future payments due to the conditional nature of the Company’s obligations and the unique facts and circumstances involved in each particular agreement. Historically, payments made by the Company under any of these indemnities have not had a material effect on the Company’s business, financial condition, results of operations or cash flows. Additionally, the Company does not believe that any amounts that it may be required to pay under these indemnities in the future will be material to the Company’s business, financial position, results of operations or cash flows. Legal Matters The Company is currently involved in a variety of legal matters that arise in the normal course of business. Based on information currently available, management does not believe that the ultimate resolution of these matters will have a material effect on the Company's financial condition, results of operations or cash flows. However, because of the nature and inherent uncertainties of litigation, the Company cannot guarantee the outcome of these actions. On August 22, 2014, Collabo Innovations, Inc. ("Collabo") filed a lawsuit in the U.S. District Court for the District of Delaware against the Company and three of its subsidiaries, all of which were acquired in the acquisition of Aptina. The complaint alleged infringement of U.S. Patent Nos. 6,166,405, 7,696,543, 5,976,907, 7,135,725 and 7,023,034 (the “Collabo Patents”) and sought unspecified damages for past infringement. The Collabo Patents relate to CMOS image sensor products. Collabo served the complaint in December 2014, the Company answered in April 2015, and Collabo dismissed U.S. Patent No. 7,153,725 from the lawsuit in June 2015. On September 30, 2015, the Company entered into a license agreement, which settles the litigation, with Collabo and its corporate parent. The licensing fee paid by the Company is not material. The case has been dismissed. Intellectual Property Matters We face risk to exposure from claims of infringement of the IP rights of others. In the ordinary course of business, we receive letters asserting that the Company's products or components breach another party’s rights. These threats may seek that we make royalty payments, that we stop use of such rights, or other remedies.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Oct. 02, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 11: Fair Value Measurements Fair Value of Financial Instruments Summarized information with respect to certain of the Company's financial assets and liabilities measured at fair value on a recurring basis as of October 2, 2015 and December 31, 2014 is as follows (in millions): Description Balance at October 2, 2015 Fair Value Balance at December 31, 2014 Fair Value Cash equivalents (Level 1): Demand and time deposits $ 25.0 $ 25.0 $ 20.3 $ 20.3 Money market funds 37.5 37.5 46.3 46.3 Other Current Assets (Level 2): Foreign currency exchange contracts $ — $ — $ 0.1 $ 0.1 Liabilities (Level 2): Designated cash flow hedges $ 1.9 $ 1.9 $ 3.5 $ 3.5 Short-Term Investments The Company's short-term investments are valued using market prices on active markets (Level 1). Short-term investments with an original maturity between three months and one year are classified as held-to-maturity and are carried at amortized cost as the Company has the intent and ability to hold these securities until maturity. Short-term investments classified as held-to-maturity as of October 2, 2015 and December 31, 2014 were as follows (in millions): Balance at October 2, 2015 Balance at December 31, 2014 Carried at Amortized Cost Fair Value Carried at Amortized Cost Fair Value Short-term investments held-to-maturity Corporate bonds $ 0.8 $ 0.8 $ 2.0 $ 2.0 Investments that are designated as available-for-sale are reported at fair value, with unrealized gains and losses, net of tax, recorded in accumulated other comprehensive loss. As of October 2, 2015 , there were no short-term investments classified as available-for-sale. As of December 31, 2014, the Company held short-term investments classified as available-for-sale, measured at Level 1, with a fair value equal to the carrying value of $4.1 million . See Note 13: ''Changes in Accumulated Other Comprehensive Loss'' for additional information on unrealized gains and losses on available-for-sale short-term investments. Fair Value of Long-Term Debt, Including Current Portion The carrying amounts and fair values of the Company’s long-term borrowings (excluding capital lease obligations, real estate mortgages and equipment financing) as of October 2, 2015 and December 31, 2014 are as follows (in millions): October 2, 2015 December 31, 2014 Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion Convertible notes $ 933.0 $ 1,035.4 $ 342.2 $ 424.8 Long-term debt $ 393.6 $ 393.1 $ 745.8 $ 744.8 The fair value of the Company's 2.625% Notes, Series B and the 1.00% Notes were estimated based on market prices in active markets (Level 1). The fair value of other long-term debt was estimated based on discounting the remaining principal and interest payments using current market rates for similar debt (Level 2) as of October 2, 2015 and December 31, 2014 . Cost Method Investments Investments in equity securities that do not qualify for fair value accounting are accounted for under the cost method. Accordingly, the Company accounts for investments in companies that it does not control, or have significant influence over, under the cost method, as applicable. If a decline in the fair value of a cost method investment is determined to be other than temporary, an impairment charge is recorded, and the fair value becomes the new cost basis of the investment. The Company evaluates all of its cost method investments for impairment; however, it is not required to determine the fair value of its investment unless impairment indicators are present. As of October 2, 2015 and December 31, 2014, the Company’s cost method investments had a carrying value of $12.3 million and $12.2 million , respectively. Other The carrying amounts of other current assets and liabilities, such as accounts receivable and accounts payable, approximate fair value based on the short-term nature of these instruments.

Financial Instruments

Financial Instruments	9 Months Ended
	Oct. 02, 2015
Investments, All Other Investments [Abstract]
Financial Instruments	Note 12: Financial Instruments Foreign Currencies As a multinational business, the Company’s transactions are denominated in a variety of currencies. When appropriate, the Company uses forward foreign currency contracts to reduce its overall exposure to the effects of currency fluctuations on its results of operations and cash flows. The Company’s policy prohibits trading in currencies for which there are no underlying exposures, or entering into trades for any currency to intentionally increase the underlying exposure. The Company primarily hedges existing assets and liabilities associated with transactions currently on its balance sheet, which are undesignated hedges for accounting purposes. As of October 2, 2015 and December 31, 2014 , the Company had net outstanding foreign exchange contracts with notional amounts of $76.6 million and $ 145.7 million , respectively. Such contracts were obtained through financial institutions and were scheduled to mature within one to three months from the time of purchase. Management believes that these financial instruments should not subject the Company to increased risks from foreign exchange movements because gains and losses on these contracts should offset losses and gains on the underlying assets, liabilities and transactions to which they are related. The following summarizes the Company’s net foreign exchange positions in U.S. dollars as of October 2, 2015 and December 31, 2014 (in millions): October 2, 2015 December 31, 2014 Buy (Sell) Notional Amount Buy (Sell) Notional Amount Euro $ (10.9 ) $ 10.9 $ (31.2 ) $ 31.2 Japanese Yen (21.2 ) 21.2 (42.1 ) 42.1 Malaysian Ringgit 2.9 2.9 39.2 39.2 Philippine Peso 17.3 17.3 16.7 16.7 Other Currencies - Buy 20.2 20.2 13.8 13.8 Other Currencies - Sell (4.1 ) 4.1 (2.7 ) 2.7 $ 4.2 $ 76.6 $ (6.3 ) $ 145.7 The Company is exposed to credit-related losses if counterparties to its foreign exchange contracts fail to perform their obligations. As of October 2, 2015 , the counterparties to the Company’s foreign currency hedge contracts as well as the cash flow hedges described below are held at financial institutions which the Company believes to be highly rated, and no credit-related losses are anticipated. Amounts receivable or payable under the contracts are included in other current assets or accrued expenses in the accompanying Consolidated Balance Sheet. For the quarters ended October 2, 2015 and September 26, 2014 , realized and unrealized foreign currency transactions totaled a $1.5 million gain and a $1.2 million loss, respectively. For the nine months ended October 2, 2015 , there was $1.4 million gain recognized from realized and unrealized foreign currency transactions. For the nine months ended September 26, 2014 , realized and unrealized foreign currency transactions totaled a loss of $2.2 million . The realized and unrealized foreign currency transactions are included in other income and expenses in the Company's Consolidated Statements of Operations and Comprehensive Income. Cash Flow Hedges The Company is exposed to global market risks associated with fluctuations in interest rates and foreign currency exchange rates. The Company addresses these risks through controlled management that includes the use of derivative financial instruments to economically hedge or reduce these exposures. The Company does not enter into derivative financial instruments for trading or speculative purposes. The purpose of the Company's foreign currency hedging activities is to protect the Company from the risk that the eventual cash flows resulting from transactions in foreign currencies will be adversely affected by changes in exchange rates. The Company enters into forward contracts that are designated as foreign-currency cash flow hedges of selected forecasted payments denominated in currencies other than U.S. dollars. All the contracts mature within 12 months, and upon maturity the amount recorded in accumulated other comprehensive income is reclassified into earnings. The Company documents all relationships between designated hedging instruments and hedged items, as well as its risk management objective and strategy for undertaking hedge transactions. All derivatives are recognized on the balance sheet at their fair value and classified based on the instrument's maturity date. The total notional amount of outstanding derivatives designated as cash flow hedges as of October 2, 2015 was $ 12.4 million , which is primarily composed of cash flow hedges for Malaysian Ringgit/U.S. dollar and Philippine Peso/U.S. dollar currency pairs. For the quarter and nine months ended October 2, 2015 , the Company recorded a net loss of $2.8 million and $6.2 million , respectively, associated with cash flow hedges recognized as a component of cost of revenues.

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Loss	9 Months Ended
	Oct. 02, 2015
Equity [Abstract]
Changes in Accumulated Other Comprehensive Loss	Note 13: Changes in Accumulated Other Comprehensive Loss Amounts comprising the Company's accumulated other comprehensive loss and reclassifications for the nine months ended October 2, 2015 are as follows (net of tax of $0 , in millions): Foreign Currency Translation Adjustments Effects of Cash Flow Hedges Gains and Losses on Available-for-Sale Securities Total Balance as of December 31, 2014 $ (42.5 ) $ (3.5 ) $ 4.5 $ (41.5 ) Other comprehensive income (loss) prior to reclassifications 0.2 7.9 (0.4 ) 7.7 Amounts reclassified from accumulated other comprehensive loss — (6.2 ) (4.1 ) (10.3 ) Net current period other comprehensive income (loss) 0.2 1.7 (4.5 ) (2.6 ) Balance as of October 2, 2015 $ (42.3 ) $ (1.8 ) $ — $ (44.1 ) Amounts which were reclassified from accumulated other comprehensive loss to the Company's Consolidated Statements of Operations and Comprehensive Income during the quarter and nine months ended October 2, 2015 , respectively, were as follows (net of tax of $0 , in millions): Amounts Reclassified from Accumulated Other Comprehensive Loss Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Affected Line Item Where Net Income is Presented Effects of cash flow hedges $ (2.8 ) $ 0.4 $ (6.2 ) $ (1.0 ) Cost of revenues Gains and Losses on Available-for-Sale Securities (0.7 ) — (4.1 ) — Other income and expense Total reclassifications $ (3.5 ) $ 0.4 $ (10.3 ) $ (1.0 ) Included in accumulated other comprehensive loss as of October 2, 2015 is $13.3 million of foreign currency translation losses related to the Company’s subsidiary that owns the KSS facility, which utilizes the Japanese Yen as its functional currency. In connection with the previously announced restructuring plan, the Company intends to liquidate the legal entity. Upon the substantial liquidation of the KSS entity, the Company will evaluate the need to release any amount remaining in accumulated other comprehensive income to its results of operations, as required by the appropriate accounting standards.

Supplemental Disclosures

Supplemental Disclosures	9 Months Ended
	Oct. 02, 2015
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosures	Note 14: Supplemental Disclosures Supplemental Disclosure of Cash Flow Information Certain of the Company's non-cash activities along with cash payments for interest and income taxes are as follows (in millions): Nine Months Ended October 2, 2015 September 26, 2014 Non-cash activities: Capital expenditures in accounts payable and other liabilities $ 105.9 $ 97.4 Equipment acquired or refinanced through capital leases $ 2.1 $ 6.1 Cash (received) paid for: Interest income $ (0.8 ) $ (0.6 ) Interest expense $ 17.9 $ 15.2 Income taxes $ 15.0 $ 15.5

Segment Information

Segment Information	9 Months Ended
	Oct. 02, 2015
Segment Reporting [Abstract]
Segment Information	Note 15: Segment Information As of October 2, 2015 , the Company was organized into four reportable segments, consisting of the Application Products Group, Standard Products Group, System Solutions Group and Image Sensor Group. Each of the Company's major product lines has been examined and each product line has been assigned to a reportable segment based on the Company's operating strategy. Because many products are sold into different end-markets, the total revenue reported for a segment is not indicative of actual sales in the end-market associated with that segment, but rather is the sum of the revenue from the product lines assigned to that segment. These segments represent the Company's view of the business and as such are used to evaluate progress of major initiatives and allocation of resources. Revenues and gross profit for the Company’s reportable segments for the quarters and nine months ended October 2, 2015 and September 26, 2014 are as follows (in millions): Application Products Group Image Sensor Group Standard Products Group System Solutions Group Total For the quarter ended October 2, 2015: Revenues from external customers $ 275.4 $ 189.4 $ 311.6 $ 127.8 $ 904.2 Segment gross profit $ 119.7 $ 62.8 $ 105.5 $ 25.7 $ 313.7 For the quarter ended September 26, 2014: Revenues from external customers $ 265.8 $ 103.6 $ 317.3 $ 146.8 $ 833.5 Segment gross profit $ 118.1 $ 23.4 $ 114.9 $ 31.0 $ 287.4 For the nine months ended October 2, 2015: Revenues from external customers $ 803.2 $ 533.1 $ 922.6 $ 396.6 $ 2,655.5 Segment gross profit $ 357.0 $ 165.5 $ 324.6 $ 79.1 $ 926.2 For the nine months ended September 26, 2014: Revenues from external customers $ 810.2 $ 139.9 $ 913.9 $ 433.6 $ 2,297.6 Segment gross profit $ 361.9 $ 43.5 $ 332.1 $ 87.8 $ 825.3 Gross profit shown above and below is exclusive of the amortization of acquisition-related intangible assets. Depreciation expense is included in segment gross profit. Reconciliations of segment gross profit to consolidated gross profit are as follows (in millions): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Gross profit for reportable segments $ 313.7 $ 287.4 $ 926.2 $ 825.3 Less: unallocated manufacturing costs (1) (5.2 ) (6.5 ) (12.9 ) (18.1 ) Consolidated Gross profit $ 308.5 $ 280.9 $ 913.3 $ 807.2 (1) During the third quarter of 2015, the Company began allocating certain manufacturing costs to its segments that were previously included as unallocated manufacturing costs. Comparative information has been recast to conform with the current period presentation. The Company's consolidated assets are not specifically ascribed to its individual reporting segments. Rather, assets used in operations are generally shared across the Company's reporting segments. The Company operates in various geographic locations. Sales to unaffiliated customers have little correlation with the location of manufacturers. It is therefore not meaningful to present gross profit by geographical location. Revenues by geographic location, including local sales made by operations within each area, based on sales billed from the respective country, are summarized as follows (in millions): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 United States $ 133.5 $ 125.5 $ 406.1 $ 352.6 Japan 74.5 77.4 201.9 210.0 Hong Kong 232.7 263.9 647.9 692.8 Singapore 270.6 210.4 881.5 580.5 United Kingdom 131.5 126.3 380.4 367.0 Other 61.4 30.0 137.7 94.7 $ 904.2 $ 833.5 $ 2,655.5 $ 2,297.6 Property, plant and equipment, net by geographic location, is summarized as follows (in millions): October 2, 2015 December 31, United States $ 315.7 $ 308.1 Czech Republic 105.0 113.8 Malaysia 227.6 232.2 Philippines 255.0 197.4 China 114.0 122.2 Other 238.8 230.2 $ 1,256.1 $ 1,203.9 For the quarters and nine months ended October 2, 2015 and September 26, 2014 , there were no individual customers, including distributors, which accounted for more than 10% of the Company's total consolidated revenues.

Background and Basis of Prese22

Background and Basis of Presentation Background and Basis of Presentation (Policies)	9 Months Ended
	Oct. 02, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Use of Estimates	The preparation of financial statements in accordance with generally accepted accounting principles in the United States of America 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. Significant estimates have been used by management in conjunction with the following: (i) measurement of valuation allowances relating to trade receivables, inventories and deferred tax assets; (ii) estimates of future payouts for customer incentives and allowances, warranties, and restructuring activities; (iii) assumptions surrounding future pension obligations; (iv) fair values of share-based compensation and of financial instruments (including derivative financial instruments); (v) evaluations of uncertain tax positions; (vi) estimates and assumptions used in connection with business combinations; and (vii) future cash flows used to assess and test for impairment of goodwill and long-lived assets, if applicable. Actual results could differ from these estimates.
Recent Accounting Pronouncements	ASU No. 2015-16 - "Simplifying the Accounting for Measurement-Period Adjustments" ("ASU 2015-16") In September 2015, the FASB issued ASU 2015-16, which requires that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amendment also requires that the acquirer record, in the same period’s financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The amendments in ASU 2015-16 also require an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods as if the adjustment to the provisional amounts had been recognized as of the acquisition date. The amendments are effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The amendments in ASU 2015-16 will be applied prospectively to adjustments to provisional amounts that occur after the effective date of ASU 2015-16, with earlier application permitted for financial statements that have not been issued. The Company has not elected early adoption as of the period ended October 2, 2015. ASU No. 2015-11 - "Simplifying the Measurement of Inventory" ("ASU 2015-11") In July 2015, the FASB issued ASU 2015-11, which requires that an entity should measure in-scope inventory at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The amendments are effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact that the adoption of ASU 2015-11 may have on its consolidated financial statements and has not elected early adoption as of the period ended October 2, 2015. ASU 2015-05 - “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement” ("ASU 2015-05") In April 2015, the FASB issued ASU 2015-05, which provides guidance regarding the accounting for fees paid by a customer in cloud computing arrangements. If a cloud computing arrangement includes a software license, then the customer would account for the payment of fees as an acquisition of software. If there is no software license, the payment of fees would be accounted for as a service contract. This ASU is effective in fiscal years beginning after December 15, 2015. An entity can elect to adopt the amendments either prospectively for all arrangements entered into or materially modified after the effective date, or retrospectively. Early adoption is permitted. The Company is currently evaluating the impact that the adoption of ASU 2015-05 may have on its consolidated financial statements and has not elected early adoption as of the period ended October 2, 2015. ASU No. 2015-03 - "Simplifying the Presentation of Debt Issuance Costs" ("ASU 2015-03") In April 2015, the FASB issued ASU 2015-03, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The new standard is effective for fiscal years beginning after December 15, 2015 and interim periods within those fiscal years. Early adoption is permitted for financial statements that have not been previously issued. The Company has not elected early adoption as of the period ended October 2, 2015 . As of October 2, 2015 , debt issuance costs of $19.7 million were recorded as assets on the Company's Consolidated Balance Sheet. ASU No. 2014-09 - “Revenue from Contracts with Customers (Topic 606)” (“ASU 2014-09”) and ASU No. 2015-14 - "Deferral of the Effective Date" ("ASU 2015-14") In May 2014, the FASB issued ASU 2014-09, which applies to any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets, unless those contracts are within the scope of other standards, superceding the revenue recognition requirements in Topic 605. Pursuant to ASU 2014-09, an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange, as applied through a multi-step process to achieve that core principle. Subsequently, the FASB approved a deferral included in ASU 2015-14 that permits public entities to apply the amendments in ASU 2014-09 for annual reporting periods beginning after December 15, 2017, including interim reporting periods therein, and that would also permit public entities to elect to adopt the amendments as of the original effective date as applicable to reporting periods beginning after December 15, 2016. The Company is currently evaluating the impact that the adoption of ASU 2014-09 and ASU 2015-14 may have on its consolidated financial statements as of the period ended October 2, 2015. As described in the 2014 Form 10-K, the Company defers the revenue and cost of revenues on sales to certain distributors until it is informed by the distributor that the distributor has resold the products to the end customer. Upon adoption of ASU 2014-09 and 2015-14, a portion of this deferred income amount may be recognized upon shipment to the distributor rather than upon sale to the end customer. The balance of deferred income on sales to distributors included on the Company's Consolidated Balance Sheet as of October 2, 2015 and December 31, 2014 , was $130.4 million and $165.1 million , respectively.
Cost Method Investments	Cost Method Investments Investments in equity securities that do not qualify for fair value accounting are accounted for under the cost method. Accordingly, the Company accounts for investments in companies that it does not control, or have significant influence over, under the cost method, as applicable. If a decline in the fair value of a cost method investment is determined to be other than temporary, an impairment charge is recorded, and the fair value becomes the new cost basis of the investment. The Company evaluates all of its cost method investments for impairment; however, it is not required to determine the fair value of its investment unless impairment indicators are present.

Background and Basis of Prese23

Background and Basis of Presentation (Tables)	9 Months Ended
	Oct. 02, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Retrospective Measurement Period Adjustments	The following tables present the effect of the aforementioned revisions and adjustments on the Company’s consolidated statement of cash flows for the nine months ended September 26, 2014 (in millions). There was no impact to total cash flows from operating activities as a result of the revisions and adjustments: Nine months ended September 26, 2014 As Reported Revision (1) As Revised Cash flows from operating activities: Net income $ 189.6 $ 2.3 $ 191.9 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization (1) 184.8 (2.4 ) 182.4 Change in deferred taxes (16.1 ) (0.6 ) (16.7 ) Changes in assets and liabilities (exclusive of the impact of acquisitions): Inventories (30.1 ) 0.7 (29.4 ) (1) Includes the business combination measurement period adjustment of $2.4 million with respect to the amortization of acquisition-related intangible assets for the quarter and nine months ended September 26, 2014 in accordance with the final purchase price allocation of Truesense as discussed above. The following tables present the effect of the aforementioned revisions and adjustments on the Company’s consolidated statements of operations and comprehensive income for the quarter and nine months ended September 26, 2014 (in millions, except per share data): Quarter Ended September 26, 2014 As Reported Revision (1) As Revised Cost of revenues (exclusive of amortization shown below) $ 549.4 $ 3.2 $ 552.6 Gross profit 284.1 (3.2 ) 280.9 Operating expenses: Amortization of acquisition-related intangible assets (1) 23.4 (2.4 ) 21.0 Operating income 57.6 (0.8 ) 56.8 Other (0.9 ) (0.3 ) (1.2 ) Other (expenses) income, net (9.3 ) (0.3 ) (9.6 ) Income before income taxes 48.3 (1.1 ) 47.2 Net income 42.0 (1.1 ) 40.9 Net income attributable to ON Semiconductor Corporation 41.6 (1.1 ) 40.5 Comprehensive income 42.7 (1.1 ) 41.6 Comprehensive income attributable to ON Semiconductor Corporation 42.3 (1.1 ) 41.2 Nine Months Ended September 26, 2014 As Reported Revision (1) As Revised Cost of revenues (exclusive of amortization shown below) $ 1,489.7 $ 0.7 $ 1,490.4 Gross profit 807.9 (0.7 ) 807.2 Operating expenses: Amortization of acquisition-related intangible assets (1) 42.0 (2.4 ) 39.6 Operating income 212.6 1.7 214.3 Other (2.7 ) 0.6 (2.1 ) Other (expenses) income, net (26.7 ) 0.6 (26.1 ) Income before income taxes 185.9 2.3 188.2 Net income 189.6 2.3 191.9 Net income attributable to ON Semiconductor Corporation 188.0 2.3 190.3 Comprehensive income 192.4 2.3 194.7 Comprehensive income attributable to ON Semiconductor Corporation 190.8 2.3 193.1 Diluted net income per common share attributable to ON Semiconductor Corporation $ 0.42 0.01 $ 0.43 (1) Includes the business combination measurement period adjustment of $2.4 million with respect to the amortization of acquisition-related intangible assets for the quarter and nine months ended September 26, 2014 in accordance with the final purchase price allocation of Truesense as discussed above. During the quarter ended April 3, 2015, the Company finalized the purchase price allocation of Aptina and, as a result, retrospectively adjusted its Consolidated Balance Sheet and related information as of December 31, 2014 for an immaterial amount as follows (in millions, see Note 3: ''Acquisitions'' for additional information): As of December 31, 2014 As Reported Revision As Revised Goodwill $ 264.7 $ (0.9 ) $ 263.8 Intangible assets, net $ 457.6 $ 0.9 $ 458.5

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Oct. 02, 2015
Business Combinations [Abstract]
Schedule of Purchase Price Allocation	The following table presents the initial allocation and subsequent adjustments applied on a retrospective basis to the purchase price of Aptina for the assets acquired and liabilities assumed on August 15, 2014 based on their fair values (in millions): Initial Estimate Adjustments Final Allocation Cash and cash equivalents $ 30.3 $ — $ 30.3 Receivables 53.2 — 53.2 Inventories 85.3 (0.5 ) 84.8 Other current assets 5.7 — 5.7 Property, plant and equipment 35.9 0.4 36.3 Goodwill 63.8 0.6 64.4 Intangible assets 183.1 24.7 207.8 In-process research and development 75.4 (24.1 ) 51.3 Other non-current assets 2.3 — 2.3 Total assets acquired 535.0 1.1 536.1 Accounts payable 66.8 (0.2 ) 66.6 Other current liabilities 51.2 (1.5 ) 49.7 Other non-current liabilities 14.5 (0.1 ) 14.4 Total liabilities assumed 132.5 (1.8 ) 130.7 Net assets acquired $ 402.5 $ 2.9 $ 405.4
Schedule of Pro forma Information	The following unaudited pro-forma consolidated results of operations for the quarter and nine months ended September 26, 2014 has been prepared as if the acquisitions of Aptina and Truesense had occurred on January 1, 2013 and includes adjustments for depreciation expense, amortization of intangibles, and the effect of purchase accounting adjustments including the step-up of inventory (in millions, except per share data): Quarter Ended Nine Months Ended September 26, 2014 September 26, 2014 Revenues $ 906.1 $ 2,672.2 Gross profit 308.5 924.3 Net income attributable to ON Semiconductor Corporation $ 22.4 $ 128.2 Net income per common share attributable to ON Semiconductor Corporation: Basic $ 0.05 $ 0.29 Diluted $ 0.05 $ 0.29

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Oct. 02, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Goodwill by Operating Segment	The following table summarizes goodwill by relevant reportable segment as of October 2, 2015 and December 31, 2014 (in millions): Balance as of October 2, 2015 Balance as of December 31, 2014 Goodwill Accumulated Impairment Losses Carrying Value Goodwill Accumulated Impairment Losses Carrying Value Reportable Segment: Application Products Group $ 547.4 $ (418.9 ) $ 128.5 $ 539.9 $ (418.9 ) $ 121.0 Image Sensor Group 95.4 — 95.4 95.4 — 95.4 Standard Products Group 76.0 (28.6 ) 47.4 76.0 (28.6 ) 47.4 $ 718.8 $ (447.5 ) $ 271.3 $ 711.3 $ (447.5 ) $ 263.8
Summary of Intangible Assets, Net	Intangible assets, net, were as follows as of October 2, 2015 and December 31, 2014 (in millions): October 2, 2015 Original Cost Accumulated Amortization Foreign Currency Translation Adjustment Accumulated Impairment Losses Carrying Value Intellectual property $ 13.9 $ (10.5 ) $ — $ (0.4 ) $ 3.0 Customer relationships 426.2 (197.0 ) (27.8 ) (23.7 ) 177.7 Patents 43.7 (23.0 ) — (13.7 ) 7.0 Developed technology 246.6 (135.7 ) — (2.6 ) 108.3 Trademarks 16.3 (9.8 ) — (1.1 ) 5.4 Backlog 0.3 (0.2 ) — — 0.1 IPRD 62.4 — — (3.8 ) 58.6 Total intangibles $ 809.4 $ (376.2 ) $ (27.8 ) $ (45.3 ) $ 360.1 December 31, 2014 Original Cost Accumulated Amortization Foreign Currency Translation Adjustment Accumulated Impairment Losses Carrying Value Intellectual property $ 13.9 $ (10.0 ) $ — $ (0.4 ) $ 3.5 Customer relationships 425.6 (146.2 ) (27.8 ) (23.7 ) 227.9 Patents 43.7 (21.3 ) — (13.7 ) 8.7 Developed technology 241.9 (88.9 ) — (2.6 ) 150.4 Trademarks 16.3 (8.7 ) — (1.1 ) 6.5 IPRD 61.5 — — — 61.5 Total intangibles $ 802.9 $ (275.1 ) $ (27.8 ) $ (41.5 ) $ 458.5
Summary of Amortization Expense	Amortization expense for intangible assets, with the exception of the $58.6 million of IPRD assets that will be amortized once the corresponding projects have been completed, is expected to be as follows for each of the next five years and thereafter (in millions): Period Estimated Amortization Expense Remainder of 2015 $ 34.0 2016 89.1 2017 57.3 2018 35.5 2019 29.9 Thereafter 55.7 Total estimated amortization expense $ 301.5

Restructuring, Asset Impairme26

Restructuring, Asset Impairments and Other, Net (Tables)	9 Months Ended
	Oct. 02, 2015
Restructuring Charges [Abstract]
Schedule of Activity Included in Restructuring, Asset Impairments, and Other, Net	Summarized activity included in the “Restructuring, asset impairments and other, net” caption on the Company's Consolidated Statements of Operations and Comprehensive Income for the quarter and nine months ended October 2, 2015 is as follows (in millions): Restructuring Impairment Other Total Quarter ended October 2, 2015 Business combination severance $ 0.2 $ — $ — $ 0.2 General Workforce Reductions 1.2 — — 1.2 Other (1) 0.3 — 1.6 1.9 Total $ 1.7 $ — $ 1.6 $ 3.3 Restructuring Impairment Other Total Nine months ended October 2, 2015 KSS facility closure $ 0.3 $ — $ (3.4 ) $ (3.1 ) Business combination severance 0.9 — — 0.9 General Workforce Reductions 1.2 — — 1.2 European marketing organization relocation 3.5 — — 3.5 Other (1) 0.5 0.2 1.3 2.0 Total $ 6.4 $ 0.2 $ (2.1 ) $ 4.5 (1) Includes amounts related to certain reductions in workforce, other facility closures, asset disposal activity and certain other activity which is not considered to be significant.
Schedule of Restructuring Reserve Roll Forward	Changes in accrued restructuring charges from December 31, 2014 to October 2, 2015 are summarized as follows (in millions): Balance as of December 31, 2014 Charges Usage Balance as of Estimated employee separation charges $ 2.3 $ 6.4 $ (4.0 ) $ 4.7 Estimated costs to exit 1.1 — (0.6 ) 0.5 Total $ 3.4 $ 6.4 $ (4.6 ) $ 5.2

Balance Sheet Information (Tabl

Balance Sheet Information (Tables)	9 Months Ended
	Oct. 02, 2015
Balance Sheet Related Disclosures [Abstract]
Supplemental Balance Sheet Information	Certain amounts included in the Company's balance sheet as of October 2, 2015 and December 31, 2014 consist of the following (dollars in millions): October 2, 2015 December 31, 2014 Receivables, net: Accounts receivable $ 509.1 $ 419.1 Less: Allowance for doubtful accounts (3.2 ) (1.6 ) $ 505.9 $ 417.5 Inventories: Raw materials $ 90.7 $ 119.7 Work in process 465.1 365.5 Finished goods 198.2 244.7 $ 754.0 $ 729.9 Other current assets: Prepaid expenses $ 34.0 $ 28.7 Value added and other income tax receivables 42.2 40.4 Acquisition consideration held in escrow (see Note 3) 40.8 40.0 Other (1) 18.2 31.5 $ 135.2 $ 140.6 Property, plant and equipment, net: Land $ 46.2 $ 46.1 Buildings 505.1 484.3 Machinery and equipment 2,314.7 2,165.0 Total property, plant and equipment 2,866.0 2,695.4 Less: Accumulated depreciation (1,609.9 ) (1,491.5 ) $ 1,256.1 $ 1,203.9 Accrued expenses: Accrued payroll $ 100.1 $ 117.0 Sales related reserves 82.8 65.8 Acquisition consideration payable to seller (see Note 3) 40.8 40.0 Other 82.7 65.1 $ 306.4 $ 287.9 (1) Included in other current assets are $0.8 million of property, plant and equipment which are held-for-sale as of October 2, 2015 .
Schedule of Product Warranty Liability	Activity related to the Company's warranty reserves for the nine months ended October 2, 2015 and September 26, 2014 is as follows (in millions): Nine Months Ended October 2, 2015 September 26, 2014 Beginning Balance $ 5.5 $ 6.0 Provision 2.0 2.0 Usage (1.5 ) (2.3 ) Ending Balance $ 6.0 $ 5.7
Schedule of Net Benefit Costs	The components of the Company's net periodic pension expense for the quarters and nine months ended October 2, 2015 and September 26, 2014 are as follows (in millions): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Service cost $ 2.1 $ 2.2 $ 6.5 $ 7.1 Interest cost 0.9 1.3 2.9 4.3 Expected return on plan assets (0.9 ) (0.9 ) (2.7 ) (2.7 ) Curtailment gain — (0.6 ) — (6.5 ) Total net periodic pension cost $ 2.1 $ 2.0 $ 6.7 $ 2.2

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Oct. 02, 2015
Debt Disclosure [Abstract]
Long-Term Debt	The Company's long-term debt consists of the following (annualized rates, dollars in millions): October 2, 2015 December 31, 2014 Senior Revolving Credit Facility due 2020, interest payable monthly at 1.69% as of $ — $ 350.0 1.00% Notes (net of discount of $104.7 million) (1) 585.3 — 2.625% Notes, Series B (net of discount of $9.2 million and $14.7 million, respectively) (2) 347.7 342.2 Loan with Japanese bank due 2015 through 2018, interest payable quarterly at 2.08% and 2.01%, respectively (3) 198.2 235.9 U.S. real estate mortgages payable monthly through 2019 at an average rate of 3.35% (4) 51.2 54.8 Loans with Philippine bank due 2015 through 2019, interest payable monthly and quarterly at an average rate of 2.49% and 2.37%, respectively (5) 28.0 54.2 Loan with Hong Kong bank, interest payable weekly at 1.44% and 1.92%, respectively (6) 25.0 35.0 Malaysia revolving line of credit, interest payable quarterly at 1.78% and 1.71%, respectively (7) 25.0 25.0 Loan with Singapore bank, interest payable weekly at 1.44% and 1.42%, respectively (6) 30.0 20.0 Vietnam revolving line of credit, interest payable quarterly and annually at an average rate of 1.79% and 1.87%, respectively (7) 22.4 10.7 Canada revolving line of credit, interest payable quarterly at 1.92% and 1.84%, respectively (7) 15.0 15.0 Loans with Philippine bank due 2016 through 2020, interest payable at 2.29% (8) 50.0 — Canada equipment financing payable monthly through 2017 at 3.81% (8) 2.8 4.2 U.S. equipment financing payable monthly through 2016 at 2.40% and 2.94%, respectively (8) 1.7 4.8 Capital lease obligations 25.4 40.8 Long-term debt, including current maturities 1,407.7 1,192.6 Less: Current maturities (539.3 ) (209.6 ) Long-term debt $ 868.4 $ 983.0 _______________________ (1) Interest is payable on June 1 and December 1 of each year at 1.00% annually. See below under the heading " 1.00% Notes " for additional information. (2) Interest is payable on June 15 and December 15 of each year at 2.625% annually. The 2.625% Notes, Series B may be put back to the Company at the option of the holders of the notes on December 15 of 2016 and 2021 or called at the option of the Company on or after December 20, 2016. The notes can be converted at any time on or after June 15, 2016. (3) This loan represents SCI LLC's non-collateralized loan with SMBC, which is guaranteed by the Company. (4) Debt arrangement collateralized by real estate, including certain of the Company's facilities in California, Oregon and Idaho. (5) $28.0 million collateralized by equipment as of October 2, 2015 with $15.0 million non-collateralized and $39.2 million collateralized by equipment as of December 31, 2014 . (6) Debt arrangement collateralized by accounts receivable. (7) Non-collateralized debt arrangement . (8) Debt arrangement collateralized by equipment.
Annual Maturities Relating To Long-Term Debt	Expected maturities relating to the Company’s long-term debt as of October 2, 2015 are as follows (in millions): Period Expected Maturities Remainder of 2015 $ 133.0 2016 433.0 2017 65.5 2018 144.6 2019 46.7 Thereafter 698.8 Total $ 1,521.6 For purposes of the table above, the 2.625% Notes, Series B are assumed to mature at the earliest conversion date.

Earnings per Share and Equity (

Earnings per Share and Equity (Tables)	9 Months Ended
	Oct. 02, 2015
Earnings Per Share [Abstract]
Earnings Per Share	Calculations of net income per common share attributable to ON Semiconductor are as follows (in millions, except per share data): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Net income attributable to ON Semiconductor Corporation $ 46.3 $ 40.5 $ 152.1 $ 190.3 Basic weighted average common shares outstanding 413.7 440.7 424.0 440.7 Dilutive effect of share-based awards 3.8 4.2 4.7 3.9 Dilutive effect of Convertible Notes — — 2.6 — Diluted weighted average common shares outstanding 417.5 444.9 431.3 444.6 Net income per common share attributable to ON Semiconductor Corporation: Basic $ 0.11 $ 0.09 $ 0.36 $ 0.43 Diluted $ 0.11 $ 0.09 $ 0.35 $ 0.43
Schedule of Share Repurchase Program	Information relating to the Company's share repurchase programs is as follows (in millions, except per share data): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Number of repurchased shares (1)(5) 9.4 2.6 28.4 5.9 Beginning accrued share repurchases (2) $ 3.0 $ — $ — $ 0.6 Aggregate purchase price 100.1 24.2 328.2 54.4 Less: ending accrued share repurchases (3) — (1.3 ) — (1.3 ) Total cash used for share repurchases $ 103.1 $ 22.9 $ 328.2 $ 53.7 Weighted-average purchase price per share (4) $ 10.64 $ 9.23 $ 11.53 $ 9.25 Available for future purchases at period end $ 648.2 $ 89.0 $ 648.2 $ 89.0 (1) None of these shares had been reissued or retired as of October 2, 2015 , but may be reissued or retired by the Company at a later date. (2) Represents unpaid amounts recorded in accrued expenses on the Company's Consolidated Balance Sheet as of the beginning of the period. (3) Represents unpaid amounts recorded in accrued expenses on the Company's Consolidated Balance Sheet as of the end of the period. (4) Exclusive of fees, commissions and other expenses. (5) Includes 5.4 million shares in the nine month period, totaling $70.0 million , repurchased concurrently with the issuance of the 1.00% Notes. See Note 7: ''Long-Term Debt'' for information with respect to the Company's long-term debt.

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Oct. 02, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary Of Share-Based Compensation Expense	Total share-based compensation expense related to the Company's employee stock options, restricted stock units, stock grant awards and ESPP for the quarters and nine months ended October 2, 2015 and September 26, 2014 was comprised as follows (in millions): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Cost of revenues $ 2.0 $ 1.7 $ 5.8 $ 4.8 Research and development 2.2 2.2 7.0 6.2 Selling and marketing 2.2 2.1 6.7 5.8 General and administrative 4.5 5.1 16.8 16.2 Share-based compensation expense before income taxes $ 10.9 $ 11.1 $ 36.3 $ 33.0 Related income tax benefits (1) — — — — Share-based compensation expense, net of taxes $ 10.9 $ 11.1 $ 36.3 $ 33.0 ____________________ (1) A majority of the Company’s share-based compensation relates to its domestic subsidiaries; therefore, no related deferred income tax benefits are recorded due to historical net operating losses at those subsidiaries.
Schedule of Share-based Compensation, Stock Options, Activity	Summarized stock option information for the nine months ended October 2, 2015 is as follows (in millions except per share and term data): Nine Months Ended October 2, 2015 Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (In-The-Money) Outstanding at December 31, 2014 8.8 $ 7.81 Granted — — Exercised (3.2 ) 7.84 Canceled (0.1 ) 7.02 Outstanding at October 2, 2015 5.5 $ 7.81 2.55 $ 10.0 Exercisable at October 2, 2015 4.9 $ 7.89 2.40 $ 8.5
Additional Information On Stock Options Outstanding	Additional information with respect to stock options outstanding as of October 2, 2015 , with exercise prices less than or above $ 9.53 per share, the effective closing price of the Company's common stock at October 2, 2015 , is as follows (number of shares in millions): Exercisable Unexercisable Total Exercise Prices Number of Shares Weighted-Average Exercise Price Number of Shares Weighted-Average Exercise Price Number of Shares Weighted-Average Exercise Price Less than $9.53 4.4 $ 7.59 0.6 $ 7.17 5.0 $ 7.54 Above $9.53 0.5 $ 10.47 — $ — 0.5 $ 10.47 Total outstanding 4.9 $ 7.89 0.6 $ 7.17 5.5 $ 7.81
Summary Of Restricted Stock Units Transactions	The following table presents summarized information with respect to the Company's restricted stock units as of October 2, 2015 and changes during the nine months ended October 2, 2015 (number of shares in millions): Number of Shares Weighted-Average Grant Date Fair Value Non-vested shares underlying restricted stock units at December 31, 2014 8.7 $ 8.66 Granted 3.1 12.89 Achieved 0.7 9.35 Released (3.3 ) 8.73 Forfeited (0.4 ) 9.25 Non-vested shares underlying restricted stock units at October 2, 2015 8.8 $ 10.15

Commitments And Contingencies (

Commitments And Contingencies (Tables)	9 Months Ended
	Oct. 02, 2015
Commitments and Contingencies Disclosure [Abstract]
Operating Leases Future Minimum Payments Receivable	The following represents future minimum lease obligations under non-cancelable operating leases as of October 2, 2015 (in millions): Remainder of 2015 $ 6.5 2016 21.4 2017 16.5 2018 11.7 2019 9.2 Thereafter 32.8 Total $ 98.1

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Oct. 02, 2015
Fair Value Disclosures [Abstract]
Fair Value Of Assets And Liabilities Measured On Recurring Basis	Summarized information with respect to certain of the Company's financial assets and liabilities measured at fair value on a recurring basis as of October 2, 2015 and December 31, 2014 is as follows (in millions): Description Balance at October 2, 2015 Fair Value Balance at December 31, 2014 Fair Value Cash equivalents (Level 1): Demand and time deposits $ 25.0 $ 25.0 $ 20.3 $ 20.3 Money market funds 37.5 37.5 46.3 46.3 Other Current Assets (Level 2): Foreign currency exchange contracts $ — $ — $ 0.1 $ 0.1 Liabilities (Level 2): Designated cash flow hedges $ 1.9 $ 1.9 $ 3.5 $ 3.5
Held-to-maturity Securities	Short-term investments classified as held-to-maturity as of October 2, 2015 and December 31, 2014 were as follows (in millions): Balance at October 2, 2015 Balance at December 31, 2014 Carried at Amortized Cost Fair Value Carried at Amortized Cost Fair Value Short-term investments held-to-maturity Corporate bonds $ 0.8 $ 0.8 $ 2.0 $ 2.0
Fair Value, by Balance Sheet Grouping	The carrying amounts and fair values of the Company’s long-term borrowings (excluding capital lease obligations, real estate mortgages and equipment financing) as of October 2, 2015 and December 31, 2014 are as follows (in millions): October 2, 2015 December 31, 2014 Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion Convertible notes $ 933.0 $ 1,035.4 $ 342.2 $ 424.8 Long-term debt $ 393.6 $ 393.1 $ 745.8 $ 744.8

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Oct. 02, 2015
Investments, All Other Investments [Abstract]
Schedule of Net Foreign Exchange Positions	The following summarizes the Company’s net foreign exchange positions in U.S. dollars as of October 2, 2015 and December 31, 2014 (in millions): October 2, 2015 December 31, 2014 Buy (Sell) Notional Amount Buy (Sell) Notional Amount Euro $ (10.9 ) $ 10.9 $ (31.2 ) $ 31.2 Japanese Yen (21.2 ) 21.2 (42.1 ) 42.1 Malaysian Ringgit 2.9 2.9 39.2 39.2 Philippine Peso 17.3 17.3 16.7 16.7 Other Currencies - Buy 20.2 20.2 13.8 13.8 Other Currencies - Sell (4.1 ) 4.1 (2.7 ) 2.7 $ 4.2 $ 76.6 $ (6.3 ) $ 145.7

Changes in Accumulated Other 34

Changes in Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Oct. 02, 2015
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Loss	Amounts comprising the Company's accumulated other comprehensive loss and reclassifications for the nine months ended October 2, 2015 are as follows (net of tax of $0 , in millions): Foreign Currency Translation Adjustments Effects of Cash Flow Hedges Gains and Losses on Available-for-Sale Securities Total Balance as of December 31, 2014 $ (42.5 ) $ (3.5 ) $ 4.5 $ (41.5 ) Other comprehensive income (loss) prior to reclassifications 0.2 7.9 (0.4 ) 7.7 Amounts reclassified from accumulated other comprehensive loss — (6.2 ) (4.1 ) (10.3 ) Net current period other comprehensive income (loss) 0.2 1.7 (4.5 ) (2.6 ) Balance as of October 2, 2015 $ (42.3 ) $ (1.8 ) $ — $ (44.1 ) Amounts which were reclassified from accumulated other comprehensive loss to the Company's Consolidated Statements of Operations and Comprehensive Income during the quarter and nine months ended October 2, 2015 , respectively, were as follows (net of tax of $0 , in millions): Amounts Reclassified from Accumulated Other Comprehensive Loss Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Affected Line Item Where Net Income is Presented Effects of cash flow hedges $ (2.8 ) $ 0.4 $ (6.2 ) $ (1.0 ) Cost of revenues Gains and Losses on Available-for-Sale Securities (0.7 ) — (4.1 ) — Other income and expense Total reclassifications $ (3.5 ) $ 0.4 $ (10.3 ) $ (1.0 )

Supplemental Disclosures (Table

Supplemental Disclosures (Tables)	9 Months Ended
	Oct. 02, 2015
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Certain of the Company's non-cash activities along with cash payments for interest and income taxes are as follows (in millions): Nine Months Ended October 2, 2015 September 26, 2014 Non-cash activities: Capital expenditures in accounts payable and other liabilities $ 105.9 $ 97.4 Equipment acquired or refinanced through capital leases $ 2.1 $ 6.1 Cash (received) paid for: Interest income $ (0.8 ) $ (0.6 ) Interest expense $ 17.9 $ 15.2 Income taxes $ 15.0 $ 15.5

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Oct. 02, 2015
Segment Reporting [Abstract]
Segment Information of Revenues, Gross Profit and Operating Income	Revenues and gross profit for the Company’s reportable segments for the quarters and nine months ended October 2, 2015 and September 26, 2014 are as follows (in millions): Application Products Group Image Sensor Group Standard Products Group System Solutions Group Total For the quarter ended October 2, 2015: Revenues from external customers $ 275.4 $ 189.4 $ 311.6 $ 127.8 $ 904.2 Segment gross profit $ 119.7 $ 62.8 $ 105.5 $ 25.7 $ 313.7 For the quarter ended September 26, 2014: Revenues from external customers $ 265.8 $ 103.6 $ 317.3 $ 146.8 $ 833.5 Segment gross profit $ 118.1 $ 23.4 $ 114.9 $ 31.0 $ 287.4 For the nine months ended October 2, 2015: Revenues from external customers $ 803.2 $ 533.1 $ 922.6 $ 396.6 $ 2,655.5 Segment gross profit $ 357.0 $ 165.5 $ 324.6 $ 79.1 $ 926.2 For the nine months ended September 26, 2014: Revenues from external customers $ 810.2 $ 139.9 $ 913.9 $ 433.6 $ 2,297.6 Segment gross profit $ 361.9 $ 43.5 $ 332.1 $ 87.8 $ 825.3
Reconciliation of Operating Profit (Loss) from Segments to Consolidated	Gross profit shown above and below is exclusive of the amortization of acquisition-related intangible assets. Depreciation expense is included in segment gross profit. Reconciliations of segment gross profit to consolidated gross profit are as follows (in millions): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 Gross profit for reportable segments $ 313.7 $ 287.4 $ 926.2 $ 825.3 Less: unallocated manufacturing costs (1) (5.2 ) (6.5 ) (12.9 ) (18.1 ) Consolidated Gross profit $ 308.5 $ 280.9 $ 913.3 $ 807.2 (1) During the third quarter of 2015, the Company began allocating certain manufacturing costs to its segments that were previously included as unallocated manufacturing costs. Comparative information has been recast to conform with the current period presentation.
Revenues by Geographic Location Including Local Sales and Exports	Revenues by geographic location, including local sales made by operations within each area, based on sales billed from the respective country, are summarized as follows (in millions): Quarter Ended Nine Months Ended October 2, 2015 September 26, 2014 October 2, 2015 September 26, 2014 United States $ 133.5 $ 125.5 $ 406.1 $ 352.6 Japan 74.5 77.4 201.9 210.0 Hong Kong 232.7 263.9 647.9 692.8 Singapore 270.6 210.4 881.5 580.5 United Kingdom 131.5 126.3 380.4 367.0 Other 61.4 30.0 137.7 94.7 $ 904.2 $ 833.5 $ 2,655.5 $ 2,297.6
Summary of Property, Plant and Equipment by Geographic Location	Property, plant and equipment, net by geographic location, is summarized as follows (in millions): October 2, 2015 December 31, United States $ 315.7 $ 308.1 Czech Republic 105.0 113.8 Malaysia 227.6 232.2 Philippines 255.0 197.4 China 114.0 122.2 Other 238.8 230.2 $ 1,256.1 $ 1,203.9

Background and Basis of Prese37

Background and Basis of Presentation (Narrative) (Details) - segment	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Fiscal quarter, number of days	91 days	91 days	275 days	269 days
Number of operating segments			4
Number of reporting segments			4

Background and Basis of Prese38

Background and Basis of Presentation (Schedule of Retrospective Measurement Period Adjustments) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014	Aug. 15, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Goodwill	$ 271.3	$ 263.8
Aptina | Retrospective Measurement Period Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Goodwill		263.8	$ 64.4
Intangible assets, net		458.5	207.8
Aptina | Retrospective Measurement Period Adjustment | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Goodwill		264.7	63.8
Intangible assets, net		457.6	183.1
Aptina | Retrospective Measurement Period Adjustment | Revision
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Goodwill		(0.9)	0.6
Intangible assets, net		$ 0.9	$ 24.7

Background and Basis of Prese39

Background and Basis of Presentation (Schedule of Retrospective Measurement Period Adjustments - Consolidated Statement of Operations and Comprehensive Income Impact) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of revenues (exclusive of amortization shown below)	$ 595.7	$ 552.6	$ 1,742.2	$ 1,490.4
Gross profit	308.5	280.9	913.3	807.2
Amortization of acquisition-related intangible assets	33.6	21	101.1	39.6
Operating income	69.4	56.8	205.6	214.3
Other	2.1	(1.2)	7.9	(2.1)
Other (expenses) income, net	(12.6)	(9.6)	(26.5)	(26.1)
Income before income taxes	56.8	47.2	179.1	188.2
Net income	46.8	40.9	154	191.9
Net income attributable to ON Semiconductor Corporation	46.3	40.5	152.1	190.3
Comprehensive income	46.3	41.6	151.4	194.7
Comprehensive income attributable to ON Semiconductor Corporation	$ 45.8	$ 41.2	$ 149.5	$ 193.1
Diluted net income per common share attributable to ON Semiconductor Corporation (in dollars per share)	$ 0.11	$ 0.09	$ 0.35	$ 0.43
Retrospective Measurement Period Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of revenues (exclusive of amortization shown below)		$ 552.6		$ 1,490.4
Gross profit		280.9		807.2
Amortization of acquisition-related intangible assets		21		39.6
Operating income		56.8		214.3
Other		(1.2)		(2.1)
Other (expenses) income, net		(9.6)		(26.1)
Income before income taxes		47.2		188.2
Net income		40.9		191.9
Net income attributable to ON Semiconductor Corporation		40.5		190.3
Comprehensive income		41.6		194.7
Comprehensive income attributable to ON Semiconductor Corporation		41.2		$ 193.1
Diluted net income per common share attributable to ON Semiconductor Corporation (in dollars per share)				$ 0.43
Retrospective Measurement Period Adjustment | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of revenues (exclusive of amortization shown below)		549.4		$ 1,489.7
Gross profit		284.1		807.9
Amortization of acquisition-related intangible assets		23.4		42
Operating income		57.6		212.6
Other		(0.9)		(2.7)
Other (expenses) income, net		(9.3)		(26.7)
Income before income taxes		48.3		185.9
Net income		42		189.6
Net income attributable to ON Semiconductor Corporation		41.6		188
Comprehensive income		42.7		192.4
Comprehensive income attributable to ON Semiconductor Corporation		42.3		$ 190.8
Diluted net income per common share attributable to ON Semiconductor Corporation (in dollars per share)				$ 0.42
Retrospective Measurement Period Adjustment | Revision
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of revenues (exclusive of amortization shown below)		3.2		$ 0.7
Gross profit		(3.2)		(0.7)
Operating income		(0.8)		1.7
Other		(0.3)		0.6
Other (expenses) income, net		(0.3)		0.6
Income before income taxes		(1.1)		2.3
Net income		(1.1)		2.3
Net income attributable to ON Semiconductor Corporation		(1.1)		2.3
Comprehensive income		(1.1)		2.3
Comprehensive income attributable to ON Semiconductor Corporation		(1.1)		$ 2.3
Diluted net income per common share attributable to ON Semiconductor Corporation (in dollars per share)				$ 0.01
Truesense Imaging, Inc. | Retrospective Measurement Period Adjustment | Revision
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Amortization of acquisition-related intangible assets		$ (2.4)		$ (2.4)

Background and Basis of Prese40

Background and Basis of Presentation (Schedule of Retrospective Measurement Period Adjustments - Consolidated Statement of Cash Flows Impact) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Cash flows from operating activities:
Net income	$ 46.8	$ 40.9	$ 154	$ 191.9
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			267.8	182.4
Change in deferred taxes			0.1	(16.7)
Changes in assets and liabilities (exclusive of the impact of acquisitions):
Inventories			$ (62.1)	(29.4)
Retrospective Measurement Period Adjustment
Cash flows from operating activities:
Net income		40.9		191.9
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				182.4
Change in deferred taxes				(16.7)
Changes in assets and liabilities (exclusive of the impact of acquisitions):
Inventories				(29.4)
Retrospective Measurement Period Adjustment | As Reported
Cash flows from operating activities:
Net income		42		189.6
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization				184.8
Change in deferred taxes				(16.1)
Changes in assets and liabilities (exclusive of the impact of acquisitions):
Inventories				(30.1)
Retrospective Measurement Period Adjustment | Revision
Cash flows from operating activities:
Net income		(1.1)		2.3
Adjustments to reconcile net income to net cash provided by operating activities:
Change in deferred taxes				(0.6)
Changes in assets and liabilities (exclusive of the impact of acquisitions):
Inventories				0.7
Truesense Imaging, Inc. | Retrospective Measurement Period Adjustment | Revision
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		$ (2.4)		$ (2.4)

Recent Accounting Pronounceme41

Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred income on sales to distributors	$ 130.4	$ 165.1
Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance cost	$ 19.7

Acquisitions (Narrative) (Detai

Acquisitions (Narrative) (Details) - USD ($) $ in Millions	Jul. 15, 2015	Aug. 15, 2014	Apr. 30, 2014	Oct. 02, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill				$ 271.3	$ 263.8
Acquisition consideration payable to seller				40.8	40
Aptina
Business Acquisition [Line Items]
Percentage acquired		100.00%
Purchase price		$ 405.4
Purchase price unpaid					2.9
Consideration placed in escrow		40		40
Aptina | Customer relationships
Business Acquisition [Line Items]
Intangible assets		126.5
Aptina | Developed technology
Business Acquisition [Line Items]
Intangible assets		$ 79
Weighted average useful life		6 years
Aptina | Trademarks
Business Acquisition [Line Items]
Intangible assets		$ 2.3
Weighted average useful life		6 months
Aptina | Minimum | Customer relationships
Business Acquisition [Line Items]
Weighted average useful life		2 years
Aptina | Maximum | Customer relationships
Business Acquisition [Line Items]
Weighted average useful life		6 years
Aptina | Retrospective Measurement Period Adjustment
Business Acquisition [Line Items]
Assets acquired, In-process research and development		$ 51.3
Intangible assets		207.8			458.5
Goodwill		64.4			$ 263.8
Acquired net assets		$ 405.4
Truesense Imaging, Inc.
Business Acquisition [Line Items]
Percentage acquired			100.00%
Purchase price			$ 95.7
AXSEM
Business Acquisition [Line Items]
Percentage acquired	100.00%
Purchase price	$ 8
Consideration placed in escrow				0.8
Acquisition consideration payable to seller	5
Acquired net assets	$ 13
AXSEM | Fair Value, Inputs, Level 3 | Non-current Liabilities
Business Acquisition [Line Items]
Acquisition consideration payable to seller				$ 5

Acquisitions (Schedule of Purch

Acquisitions (Schedule of Purchase Price Allocation) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014	Aug. 15, 2014
Business Acquisition [Line Items]
Goodwill	$ 271.3	$ 263.8
Retrospective Measurement Period Adjustment | Aptina
Business Acquisition [Line Items]
Cash and cash equivalents			$ 30.3
Receivables			53.2
Inventories			84.8
Other current assets			5.7
Property, plant and equipment			36.3
Goodwill		263.8	64.4
Intangible assets		458.5	207.8
In-process research and development			51.3
Other non-current assets			2.3
Total assets acquired			536.1
Accounts payable			66.6
Other current liabilities			49.7
Other non-current liabilities			14.4
Total liabilities assumed			130.7
Net assets acquired			405.4
Retrospective Measurement Period Adjustment | As Reported | Aptina
Business Acquisition [Line Items]
Cash and cash equivalents			30.3
Receivables			53.2
Inventories			85.3
Other current assets			5.7
Property, plant and equipment			35.9
Goodwill		264.7	63.8
Intangible assets		457.6	183.1
In-process research and development			75.4
Other non-current assets			2.3
Total assets acquired			535
Accounts payable			66.8
Other current liabilities			51.2
Other non-current liabilities			14.5
Total liabilities assumed			132.5
Net assets acquired			402.5
Retrospective Measurement Period Adjustment | Revision | Aptina
Business Acquisition [Line Items]
Cash and cash equivalents			0
Receivables			0
Inventories			(0.5)
Other current assets			0
Property, plant and equipment			0.4
Goodwill		(0.9)	0.6
Intangible assets		$ 0.9	24.7
In-process research and development			(24.1)
Other non-current assets			0
Total assets acquired			1.1
Accounts payable			(0.2)
Other current liabilities			(1.5)
Other non-current liabilities			(0.1)
Total liabilities assumed			(1.8)
Net assets acquired			$ 2.9

Acquisitions (Schedule of Pro F

Acquisitions (Schedule of Pro Forma Information) (Details) - Aptima, Inc. and Truesense Imaging, Inc. - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 26, 2014	Sep. 26, 2014
Business Acquisition, Pro Forma Information [Abstract]
Revenues	$ 906.1	$ 2,672.2
Gross profit	308.5	924.3
Net income attributable to ON Semiconductor Corporation	$ 22.4	$ 128.2
Net income per common share attributable to ON Semiconductor Corporation, Basic (dollars per share)	$ 0.05	$ 0.29
Net income per common share attributable to ON Semiconductor Corporation, Diluted (dollars per share)	$ 0.05	$ 0.29

Goodwill and Intangible Asset45

Goodwill and Intangible Assets (Summary of Changes in Goodwill) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Goodwill
Goodwill	$ 718.8	$ 711.3
Accumulated Impairment Losses	(447.5)	(447.5)
Carrying Value	271.3	263.8
Operating Segments | Application Products Group
Goodwill
Goodwill	547.4	539.9
Accumulated Impairment Losses	(418.9)	(418.9)
Carrying Value	128.5	121
Operating Segments | Image Sensor Group
Goodwill
Goodwill	95.4	95.4
Accumulated Impairment Losses	0	0
Carrying Value	95.4	95.4
Operating Segments | Standard Products Group
Goodwill
Goodwill	76	76
Accumulated Impairment Losses	(28.6)	(28.6)
Carrying Value	$ 47.4	$ 47.4

Goodwill and Intangible Asset46

Goodwill and Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Goodwill and intangible asset impairment	$ 0.1	$ 0	$ 3.8	$ 0
Amortization of acquisition-related intangible assets	33.6	$ 21	101.1	$ 39.6
Intangible assets, net	360.1		360.1		$ 458.5
IPRD
Finite-Lived Intangible Assets [Line Items]
Goodwill and intangible asset impairment	0.1		3.8
IPRD projects reclassified to developed technology			3.4
Intangible assets, net	58.6		58.6		$ 61.5
AXSEM
Finite-Lived Intangible Assets [Line Items]
Goodwill acquired	$ 7.5
Intangible assets acquired			$ 6.5

Goodwill and Intangible Asset47

Goodwill and Intangible Assets (Summary of Intangible Assets, Net) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Oct. 02, 2015	Dec. 31, 2014
Intangible Assets, Net
Original Cost	$ 809.4	$ 802.9
Accumulated Amortization	(376.2)	(275.1)
Foreign Currency Translation Adjustment	(27.8)	(27.8)
Impairment of Intangible Assets (Excluding Goodwill)	(45.3)	(41.5)
Carrying Value	360.1	458.5
Intellectual property
Intangible Assets, Net
Original Cost	13.9	13.9
Accumulated Amortization	(10.5)	(10)
Foreign Currency Translation Adjustment	0	0
Impairment of Intangible Assets (Excluding Goodwill)	(0.4)	(0.4)
Carrying Value	3	3.5
Customer relationships
Intangible Assets, Net
Original Cost	426.2	425.6
Accumulated Amortization	(197)	(146.2)
Foreign Currency Translation Adjustment	(27.8)	(27.8)
Impairment of Intangible Assets (Excluding Goodwill)	(23.7)	(23.7)
Carrying Value	177.7	227.9
Patents
Intangible Assets, Net
Original Cost	43.7	43.7
Accumulated Amortization	(23)	(21.3)
Foreign Currency Translation Adjustment	0	0
Impairment of Intangible Assets (Excluding Goodwill)	(13.7)	(13.7)
Carrying Value	7	8.7
Developed technology
Intangible Assets, Net
Original Cost	246.6	241.9
Accumulated Amortization	(135.7)	(88.9)
Foreign Currency Translation Adjustment	0	0
Impairment of Intangible Assets (Excluding Goodwill)	(2.6)	(2.6)
Carrying Value	108.3	150.4
Trademarks
Intangible Assets, Net
Original Cost	16.3	16.3
Accumulated Amortization	(9.8)	(8.7)
Foreign Currency Translation Adjustment	0	0
Impairment of Intangible Assets (Excluding Goodwill)	(1.1)	(1.1)
Carrying Value	5.4	6.5
Backlog
Intangible Assets, Net
Original Cost	0.3
Accumulated Amortization	(0.2)
Foreign Currency Translation Adjustment	0
Impairment of Intangible Assets (Excluding Goodwill)	0
Carrying Value	0.1
IPRD
Intangible Assets, Net
Original Cost	62.4	61.5
Accumulated Amortization	0	0
Foreign Currency Translation Adjustment	0	0
Impairment of Intangible Assets (Excluding Goodwill)	(3.8)	0
Carrying Value	$ 58.6	$ 61.5

Goodwill and Intangible Asset48

Goodwill and Intangible Assets (Summary of Amortization Expense) (Details) $ in Millions	Oct. 02, 2015USD ($)
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule
Remainder of 2015	$ 34
2,016	89.1
2,017	57.3
2,018	35.5
2,019	29.9
Thereafter	55.7
Total estimated amortization expense	$ 301.5

Restructuring, Asset Impairme49

Restructuring, Asset Impairments and Other, Net (Schedule of Activity Included in Restructuring, Asset Impairments, and Other, Net) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring	$ 1.7		$ 6.4
Impairment	0		0.2	$ 1.8
Other	1.6		(2.1)
Restructuring Costs and Asset Impairment Charges	3.3	$ 10.1	4.5	$ 20
Facility closing | KSS facility closure
Restructuring Cost and Reserve [Line Items]
Restructuring			0.3
Impairment			0
Other			(3.4)
Restructuring Costs and Asset Impairment Charges			(3.1)
Employee severance | Business combination severance
Restructuring Cost and Reserve [Line Items]
Restructuring	0.2		0.9
Impairment	0		0
Other	0		0
Restructuring Costs and Asset Impairment Charges	0.2		0.9
Employee severance | European marketing organization relocation
Restructuring Cost and Reserve [Line Items]
Restructuring			3.5
Impairment			0
Other			0
Restructuring Costs and Asset Impairment Charges			3.5
Workforce reduction | General Workforce Reductions
Restructuring Cost and Reserve [Line Items]
Restructuring	1.2		1.2
Impairment	0		0
Other	0		0
Restructuring Costs and Asset Impairment Charges	1.2		1.2
Other
Restructuring Cost and Reserve [Line Items]
Restructuring	0.3		0.5
Impairment	0		0.2
Other	1.6		1.3
Restructuring Costs and Asset Impairment Charges	$ 1.9		$ 2

Restructuring, Asset Impairme50

Restructuring, Asset Impairments and Other, Net (Rollforward of Accrued Restructuring Charges) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Oct. 02, 2015	Oct. 02, 2015
Restructuring Reserve [Roll Forward]
Balance at Beginning of Period		$ 3.4
Restructuring Costs	$ 1.7	6.4
Usage		(4.6)
Balance at End of Period	5.2	5.2
Estimated employee separation charges
Restructuring Reserve [Roll Forward]
Balance at Beginning of Period		2.3
Restructuring Costs		6.4
Usage		(4)
Balance at End of Period	4.7	4.7
Estimated costs to exit
Restructuring Reserve [Roll Forward]
Balance at Beginning of Period		1.1
Restructuring Costs		0
Usage		(0.6)
Balance at End of Period	$ 0.5	$ 0.5

Restructuring, Asset Impairme51

Restructuring, Asset Impairments and Other, Net (Narrative) (Details)	Oct. 06, 2013employees	Oct. 28, 2015employees	Dec. 31, 2015USD ($)employees	Oct. 02, 2015USD ($)employees	Apr. 03, 2015employees	Oct. 02, 2015USD ($)employees	Dec. 31, 2014USD ($)
Restructuring Cost and Reserve [Line Items]
Payments for restructuring						$ 4,600,000
Accrued liabilities				$ 5,200,000		5,200,000	$ 3,400,000
Aptina | Employee severance
Restructuring Cost and Reserve [Line Items]
Expected reduction in employment levels | employees					44
Restructuring Charges				200,000		900,000
Total employee separation charges expected to incur				1,200,000		1,200,000
Accrued liabilities				300,000		300,000
Aptina | Employee severance | Forecast
Restructuring Cost and Reserve [Line Items]
Expected reduction in employment levels | employees			12
KSS Facility Closure
Restructuring Cost and Reserve [Line Items]
Gain (loss) on disposal						3,400,000
KSS Facility Closure | Facility closing
Restructuring Cost and Reserve [Line Items]
Expected number of employees eliminated | employees	170
KSS Facility Closure | Facility closing | Contract employee
Restructuring Cost and Reserve [Line Items]
Expected reduction in employment levels | employees	40
KSS Facility Closure | Employee severance
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				0		$ 300,000
European marketing organization relocation | Employee severance
Restructuring Cost and Reserve [Line Items]
Expected reduction in employment levels | employees						6
Restructuring Charges				0		$ 3,500,000
Total employee separation charges expected to incur				3,500,000		3,500,000
Accrued liabilities				$ 3,300,000		3,300,000
General Workforce Reductions | Workforce reduction
Restructuring Cost and Reserve [Line Items]
Expected reduction in employment levels | employees				43
Restructuring Charges				$ 1,200,000
Payments for restructuring				700,000
Accrued liabilities				$ 500,000		$ 500,000
General Workforce Reductions | Workforce reduction | Subsequent Event | Minimum
Restructuring Cost and Reserve [Line Items]
Expected reduction in employment levels | employees		90
General Workforce Reductions | Workforce reduction | Subsequent Event | Maximum
Restructuring Cost and Reserve [Line Items]
Expected reduction in employment levels | employees		100
General Workforce Reductions | Workforce reduction | Forecast | Subsequent Event | Minimum
Restructuring Cost and Reserve [Line Items]
Total employee separation charges expected to incur			$ 4,000,000
General Workforce Reductions | Workforce reduction | Forecast | Subsequent Event | Maximum
Restructuring Cost and Reserve [Line Items]
Total employee separation charges expected to incur			$ 5,000,000

Balance Sheet Information (Sche

Balance Sheet Information (Schedule of Balance Sheet Information) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Receivables, net:
Accounts receivable	$ 509.1	$ 419.1
Less: Allowance for doubtful accounts	(3.2)	(1.6)
Accounts receivable, net	505.9	417.5
Inventories:
Raw materials	90.7	119.7
Work in process	465.1	365.5
Finished goods	198.2	244.7
Inventories	754	729.9
Other current assets:
Prepaid expenses	34	28.7
Value added and other income tax receivables	42.2	40.4
Acquisition consideration held in escrow	40.8	40
Other1	18.2	31.5
Other current assets	135.2	140.6
Property, plant and equipment, net:
Land	46.2	46.1
Buildings	505.1	484.3
Machinery and equipment	2,314.7	2,165
Total property, plant and equipment	2,866	2,695.4
Less: Accumulated depreciation	(1,609.9)	(1,491.5)
Property, plant and equipment, net	1,256.1	1,203.9
Accrued expenses:
Accrued payroll	100.1	117
Sales related reserves	82.8	65.8
Acquisition consideration payable to seller	40.8	40
Other	82.7	65.1
Accrued expenses	306.4	$ 287.9
Property, plant and equipment held for sale	$ 0.8

Balance Sheet Information (Warr

Balance Sheet Information (Warranty Reserves) (Details) - USD ($) $ in Millions	9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014
Warranty Reserves
Beginning Balance	$ 5.5	$ 6
Provision	2	2
Usage	(1.5)	(2.3)
Ending Balance	$ 6	$ 5.7

Balance Sheet Information (Narr

Balance Sheet Information (Narrative) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Balance Sheet Related Disclosures [Abstract]
Accrued pension liability	$ 94.1	$ 96.1
Current portion accrued pension liability	$ 0.1	$ 0.2

Balance Sheet Information (Peri

Balance Sheet Information (Periodic Pension Expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Balance Sheet Related Disclosures [Abstract]
Service cost	$ 2.1	$ 2.2	$ 6.5	$ 7.1
Interest cost	0.9	1.3	2.9	4.3
Expected return on plan assets	(0.9)	(0.9)	(2.7)	(2.7)
Curtailment gain	0	(0.6)	0	(6.5)
Total net periodic pension cost	$ 2.1	$ 2	$ 6.7	$ 2.2

Long-Term Debt (Long-Term Debt)

Long-Term Debt (Long-Term Debt) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Jun. 08, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt	$ 1,521.6
Capital lease obligations	169.2
Long-term debt, including current maturities	1,407.7		$ 1,192.6
Less: Current maturities	(539.3)		(209.6)
Long-term debt	$ 868.4		983
1.00% Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	1.00%
Senior Revolving Credit Facility due 2020, interest payable monthly at 1.69% as of December 31, 2014
Debt Instrument [Line Items]
Long-term debt	$ 0		$ 350
Debt instrument, interest rate			1.69%
Convertible Debt | 1.00% Notes
Debt Instrument [Line Items]
Long-term debt	$ 585.3		$ 0
Debt instrument, interest rate	1.00%	1.00%
Debt instrument, discount	$ 104.7
2.625% Notes, Series B (net of discount)
Debt Instrument [Line Items]
Long-term debt	$ 347.7		$ 342.2
Debt instrument, interest rate	2.625%		2.625%
Debt instrument, discount	$ 9.2		$ 14.7
Loan with Japanese bank due 2015 through 2018, interest payable quarterly at 2.08% and 2.01%, respectively
Debt Instrument [Line Items]
Long-term debt	$ 198.2		$ 235.9
Debt instrument, interest rate	2.08%		2.01%
U.S. real estate mortgages payable monthly through 2019 at an average rate of 3.35%
Debt Instrument [Line Items]
Long-term debt	$ 51.2		$ 54.8
Debt instrument, interest rate	3.35%		3.35%
Loans with Philippine bank due 2015 through 2019, interest payable monthly and quarterly at an average rate of 2.49% and 2.37%, respectively
Debt Instrument [Line Items]
Long-term debt	$ 28		$ 54.2
Debt instrument, interest rate	2.49%		2.37%
Secured Debt	$ 28		$ 39.2
Unsecured Debt			15
Loan with Hong Kong bank, interest payable weekly at 1.44% and 1.92%, respectively
Debt Instrument [Line Items]
Long-term debt	$ 25		$ 35
Debt instrument, interest rate	1.44%		1.92%
Malaysia revolving line of credit, interest payable quarterly at 1.78% and 1.71%, respectively
Debt Instrument [Line Items]
Long-term debt	$ 25		$ 25
Debt instrument, interest rate	1.78%		1.71%
Loan with Singapore bank, interest payable weekly at 1.44% and 1.42%, respectively
Debt Instrument [Line Items]
Long-term debt	$ 30		$ 20
Debt instrument, interest rate	1.44%		1.42%
Vietnam revolving line of credit, interest payable quarterly and annually at an average rate of 1.79% and 1.87%, respectively
Debt Instrument [Line Items]
Long-term debt	$ 22.4		$ 10.7
Debt instrument, interest rate	1.79%		1.87%
Canada revolving line of credit, interest payable quarterly at 1.92% and 1.84%, respectively
Debt Instrument [Line Items]
Long-term debt	$ 15		$ 15
Debt instrument, interest rate	1.92%		1.84%
Loans with Philippine bank due 2016 through 2020, interest payable at 2.29%
Debt Instrument [Line Items]
Long-term debt	$ 50		$ 0
Debt instrument, interest rate	2.29%
Canada equipment financing payable monthly through 2017 at 3.81%
Debt Instrument [Line Items]
Long-term debt	$ 2.8		$ 4.2
Debt instrument, interest rate	3.81%		3.81%
U.S. equipment financing payable monthly through 2016 at 2.40%
Debt Instrument [Line Items]
Long-term debt	$ 1.7		$ 4.8
Debt instrument, interest rate	2.40%		2.94%
Capital lease obligations
Debt Instrument [Line Items]
Capital lease obligations	$ 25.4		$ 40.8

Long-Term Debt (Annual Maturiti

Long-Term Debt (Annual Maturities Relating To Long-Term Debt) (Details) $ in Millions	Oct. 02, 2015USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
Remainder of 2015	$ 133
2,016	433
2,017	65.5
2,018	144.6
2,019	46.7
Thereafter	698.8
Total	$ 1,521.6

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) $ / shares in Units, shares in Millions	Jun. 08, 2015USD ($)	May. 01, 2015USD ($)	Oct. 02, 2015USD ($)loanpayment$ / sharesshares	Jul. 03, 2015USD ($)	Oct. 02, 2015USD ($)sharesloanpaymentd$ / shares	Sep. 26, 2014USD ($)	Dec. 31, 2014USD ($)	Oct. 10, 2013USD ($)
Debt Instrument [Line Items]
Repayment of long-term debt					$ 478,400,000	$ 63,300,000
Payments for hedge					108,900,000	0
Proceeds from issuance of warrants					$ 52,000,000	$ 0
1.00% Notes
Debt Instrument [Line Items]
Debt instrument, interest rate			1.00%		1.00%
Exercise price, warrants (in dollars per share) | $ / shares			$ 25.96		$ 25.96
2.625% Notes, Series B
Debt Instrument [Line Items]
Debt instrument, interest rate			2.625%		2.625%		2.625%
Debt instrument, discount			$ 9,200,000		$ 9,200,000		$ 14,700,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity		$ 1,000,000,000						$ 800,000,000
Debt term		5 years
Debt issuance cost				$ 2,100,000	2,100,000
Write off of existing debt issuance costs				$ 400,000	$ 400,000
Repayment of long-term debt	$ 350,000,000
Convertible Debt | 1.00% Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	1.00%		1.00%		1.00%
Debt issuance cost	$ 18,300,000
Debt instrument, face amount	690,000,000
Capitalized debt issuance costs	15,400,000		$ 14,600,000		$ 14,600,000
Conversion option recorded to equity	$ 2,900,000
Shares repurchased value					$ 70,000,000
Conversion ratio					0.0540643
Conversion price per share (in dollars per share) | $ / shares			$ 18.50		$ 18.50
Redemption price percentage					100.00%
Conversion option, debt discount					$ 110,400,000
Effective interest rate			4.29%		4.29%
Debt instrument, discount			$ 104,700,000		$ 104,700,000
Convertible note hedge			$ 56,900,000		$ 56,900,000
Number of shares convertible, warrants (in shares) | shares			37.3		37.3
Convertible Debt | 1.00% Notes | Embedded Derivative Financial Instruments
Debt Instrument [Line Items]
Conversion price per share (in dollars per share) | $ / shares			$ 18.5		$ 18.5
Number of convertible shares (in shares) | shares					37.3
Payments for hedge					$ 108,900,000
Convertible Debt | 1.00% Notes | Debt Conversion One
Debt Instrument [Line Items]
Threshold trading days | d					20
Threshold consecutive trading days					30 days
Threshold percentage of stock price trigger					130.00%
Convertible Debt | 1.00% Notes | Debt Conversion Two
Debt Instrument [Line Items]
Threshold consecutive trading days					5 days
Ratio of trading price per 1000 principal amount (as a percent)					0.98
Philippine Term Loans
Debt Instrument [Line Items]
Debt instrument, interest rate			2.29%		2.29%
Secured Debt | Philippine Term Loans
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity			$ 50,000,000		$ 50,000,000
Debt term			5 years
Debt instrument, face amount			$ 50,000,000		$ 50,000,000
Number of loans | loan			2		2
Number of quarterly payments | payment			17		17
Secured Debt | Philippine Term Loans | 3 month LIBOR
Debt Instrument [Line Items]
Spread on variable rate			2.00%

Earnings per Share and Equity59

Earnings per Share and Equity (Income per Share Calculations) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Earnings Per Share [Abstract]
Net income attributable to ON Semiconductor Corporation	$ 46.3	$ 40.5	$ 152.1	$ 190.3
Basic weighted average common shares outstanding (in shares)	413.7	440.7	424	440.7
Dilutive effect of share-based awards (in shares)	3.8	4.2	4.7	3.9
Dilutive effect of Convertible Notes (in shares)	0	0	2.6	0
Diluted weighted average common shares outstanding (in shares)	417.5	444.9	431.3	444.6
Net income per common share attributable to ON Semiconductor Corporation:
Basic (in dollars per share)	$ 0.11	$ 0.09	$ 0.36	$ 0.43
Diluted (in dollars per share)	$ 0.11	$ 0.09	$ 0.35	$ 0.43

Earnings per Share and Equity60

Earnings per Share and Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014	Jun. 08, 2015	Dec. 31, 2014	Dec. 31, 2013
Dividends Payable [Line Items]
Anti-dilutive shares	2,200,000	3,800,000	1,500,000	6,200,000
Payments of tax withholding for restricted shares	$ 1		$ 12.4	$ 6
Common stock withheld underlying restricted stock units (less than)	100,000		1,000,000
Treasury stock, shares, reissued or retired during period			0
Non-controlling interest in consolidated subsidiary	$ 22.8	$ 31.7	$ 22.8	31.7		$ 20.9	$ 32.8
Net income attributable to non-controlling interest	$ (0.5)	$ (0.4)	(1.9)	(1.6)
Dividend paid to non-controlling shareholder			$ 0	$ 2.7
2.625% Notes, Series B
Dividends Payable [Line Items]
Debt instrument, interest rate	2.625%		2.625%			2.625%
1.00% Notes
Dividends Payable [Line Items]
Debt instrument, interest rate	1.00%		1.00%
1.00% Notes | Convertible Debt
Dividends Payable [Line Items]
Debt instrument, interest rate	1.00%		1.00%		1.00%
Average price of common stock to exceed to include effect of additional potential shares			$ 25.96
Conversion price per share (in dollars per share)	$ 18.50		$ 18.50

Earnings per Share and Equity61

Earnings per Share and Equity (Summary of Share Repurchase Program) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014	Jun. 08, 2015
Earnings Per Share [Abstract]
Number of repurchased shares (in shares)	9.4	2.6	28.4	5.9
Beginning accrued share repurchases	$ 3	$ 0	$ 0	$ 0.6
Aggregate purchase price	100.1	24.2	328.2	54.4
Less: ending accrued share repurchases	0	(1.3)	0	(1.3)
Total cash used for share repurchases	$ 103.1	$ 22.9	$ 328.2	$ 53.7
Weighted-average purchase price per share (in dollars per share)	$ 10.64	$ 9.23	$ 11.53	$ 9.25
Available for future purchases at period end	$ 648.2	$ 89	$ 648.2	$ 89
Equity, Class of Treasury Stock [Line Items]
Number of repurchased shares (in shares)	9.4	2.6	28.4	5.9
1.00% Notes
Equity, Class of Treasury Stock [Line Items]
Debt instrument, interest rate	1.00%		1.00%
Convertible Debt | 1.00% Notes
Earnings Per Share [Abstract]
Number of repurchased shares (in shares)			5.4
Equity, Class of Treasury Stock [Line Items]
Number of repurchased shares (in shares)			5.4
Shares repurchased value			$ 70
Debt instrument, interest rate	1.00%		1.00%		1.00%

Share-Based Compensation (Summa

Share-Based Compensation (Summary Of Share-Based Compensation Expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense before income taxes	$ 10.9	$ 11.1	$ 36.3	$ 33
Related income tax benefits	0	0	0	0
Share-based compensation expense, net of taxes	10.9	11.1	36.3	33
Cost of revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense before income taxes	2	1.7	5.8	4.8
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense before income taxes	2.2	2.2	7	6.2
Selling and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense before income taxes	2.2	2.1	6.7	5.8
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense before income taxes	$ 4.5	$ 5.1	$ 16.8	$ 16.2

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	May. 20, 2015	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash received from exercise of stock options				$ 25.1	$ 20.4
Share price		$ 9.53		$ 9.53
Amended And Restated Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate of common stock available for grant		29.7		29.7		35.2
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized share-based compensation expense on non-vested stock options		$ 1.1		$ 1.1
Stock option, weighted average period for recognition				8 months 12 days
Total Intrinsic value of stock options exercised		0.5		$ 12.2
Cash received from exercise of stock options		$ 1.4		$ 25.1
Options pre-vesting forfeitures estimated		11.00%	11.00%	11.00%	11.00%
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized share-based compensation expense on non-vested stock options		$ 50.9		$ 50.9
Stock option, weighted average period for recognition				1 year 7 months 6 days
Options pre-vesting forfeitures estimated		5.00%	5.00%	5.00%	5.00%
Equity awards granted in period (in shares)				3.1
Weighted average grant date fair value (in dollars per share)				$ 12.89
Restricted Stock Units [Member] | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award Vesting Period				3 years
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate of common stock available for grant		7.2		7.2		3
Increase in number of shares available for grant	5.5
Restricted Stock [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity awards granted in period (in shares)				0.1
Weighted average grant date fair value (in dollars per share)				$ 12.50

Share-Based Compensation (Sum64

Share-Based Compensation (Summary Of Stock Option Plans) (Details) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Oct. 02, 2015USD ($)$ / sharesshares
Number of Shares
Number of Shares, Outstanding Beginning (in shares)	8.8
Number of Shares, Granted (in shares)	0
Number of Shares, Exercised (in shares)	(3.2)
Number of Shares, Canceled (in shares)	(0.1)
Number of Shares, Outstanding Ending (in shares)	5.5
Weighted-Average Exercise Price
Weighted-Average Exercise Price, Outstanding Beginning (in dollars per share) | $ / shares	$ 7.81
Weighted-Average Exercise Price. Granted (in dollars per share) | $ / shares	0
Weighted-Average Exercise Price, Exercised (in dollars per share) | $ / shares	7.84
Weighted-Average Exercise Price, Canceled (in dollars per share) | $ / shares	7.02
Weighted-Average Exercise Price, Outstanding Ending (in dollars per share) | $ / shares	$ 7.81
Weighted Average Remaining Contractual Term (in years), Outstanding	2 years 6 months 18 days
Aggregate Intrinsic Value (In-The-Money), Outstanding | $	$ 10
Number of Shares, Exercisable (in shares)	4.9
Weighted-Average Exercise Price, Exercisable (in dollars per share) | $ / shares	$ 7.89
Weighted-Average Remaining Contractual Term (in years), Exercisable	2 years 4 months 24 days
Aggregate Intrinsic Value (In-The-Money), Exercisable | $	$ 8.5

Share-Based Compensation (Addit

Share-Based Compensation (Additional Information On Stock Options Outstanding) (Details) shares in Millions	9 Months Ended
	Oct. 02, 2015$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares, Exercisable (in shares) | shares	4.9
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 7.89
Number of Shares, Unexercisable (in shares) | shares	0.6
Weighted Average Exercise Price, Unexercisable (in dollars per share)	$ 7.17
Number of Shares, Total (in shares) | shares	5.5
Weighted Average Exercise Price, Total (in dollars per share)	$ 7.81
Less than $9.53
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, upper range limit (in dollars per share)	$ 9.53
Number of Shares, Exercisable (in shares) | shares	4.4
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 7.59
Number of Shares, Unexercisable (in shares) | shares	0.6
Weighted Average Exercise Price, Unexercisable (in dollars per share)	$ 7.17
Number of Shares, Total (in shares) | shares	5
Weighted Average Exercise Price, Total (in dollars per share)	$ 7.54
$9.53
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise rice range, lower range limit (in dollars per share)	$ 9.53
Number of Shares, Exercisable (in shares) | shares	0.5
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 10.47
Number of Shares, Unexercisable (in shares) | shares	0
Weighted Average Exercise Price, Unexercisable (in dollars per share)	$ 0
Number of Shares, Total (in shares) | shares	0.5
Weighted Average Exercise Price, Total (in dollars per share)	$ 10.47

Share-Based Compensation (Sum66

Share-Based Compensation (Summary Of Restricted Stock Units Transactions) (Details) - Restricted Stock Units [Member] shares in Millions	9 Months Ended
	Oct. 02, 2015$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Nonvested shares underlying restricted stock units, beginning (in shares)	8.7
Number of Shares, Granted (in shares)	3.1
Number of Shares, Achieved (in shares)	0.7
Number of Shares, Released (in shares)	(3.3)
Number of Shares, Forfeited (in shares)	(0.4)
Nonvested shares underlying restricted stock units, ending (in shares)	8.8
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted Average Grant Date Fair Value, Nonvested, beginning (in dollars per share) | $ / shares	$ 8.66
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	12.89
Weighted Average Grant Date Fair Value, Achieved (in dollars per share) | $ / shares	9.35
Weighted-Average Grant Date Fair Value, Released (in dollars per share) | $ / shares	8.73
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	9.25
Weighted Average Grant Date Fair Value, Nonvested, ending (in dollars per share) | $ / shares	$ 10.15

Commitments And Contingencies67

Commitments And Contingencies (Operating Leases Future Minimum Payments Receivable) (Details) $ in Millions	Oct. 02, 2015USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2015	$ 6.5
2,016	21.4
2,017	16.5
2,018	11.7
2,019	9.2
Thereafter	32.8
Total	$ 98.1

Commitments And Contingencies68

Commitments And Contingencies (Narrative) (Details) $ in Millions	Oct. 02, 2015USD ($)	Dec. 31, 2014USD ($)	Aug. 22, 2014subsidiary
Loss Contingencies [Line Items]
Outstanding guarantees and letters of credit	$ 4.8
Guarantees related to capital lease obligations	169.2
Long-term debt	1,521.6
Collabo Innovations, Inc.
Loss Contingencies [Line Items]
Number of subsidiaries named as defendant | subsidiary			3
Unsecured Loan with SMBC
Loss Contingencies [Line Items]
Long-term debt	198.2	$ 235.9
Revolving Credit Facility | Line of Credit
Loss Contingencies [Line Items]
Line of credit, current borrowing capacity	15
Letter of Credit | Line of Credit
Loss Contingencies [Line Items]
Credit commitment outstanding	$ 0.2

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Fair Value, Inputs, Level 1 | Demand and time deposits
Assets
Cash equivalents	$ 25	$ 20.3
Fair Value, Inputs, Level 1 | Money market funds
Assets
Cash equivalents	37.5	46.3
Fair Value, Inputs, Level 2 | Cash Flow Hedges
Liabilities
Designated cash flow hedges	1.9	3.5
Fair Value, Inputs, Level 2 | Foreign currency exchange contracts
Assets
Foreign currency exchange contracts	0	0.1
Estimate of Fair Value | Fair Value, Inputs, Level 1 | Demand and time deposits
Assets
Cash equivalents	25	20.3
Estimate of Fair Value | Fair Value, Inputs, Level 1 | Money market funds
Assets
Cash equivalents	37.5	46.3
Estimate of Fair Value | Fair Value, Inputs, Level 2 | Cash Flow Hedges
Liabilities
Designated cash flow hedges	1.9	3.5
Estimate of Fair Value | Fair Value, Inputs, Level 2 | Foreign currency exchange contracts
Assets
Foreign currency exchange contracts	$ 0	$ 0.1

Fair Value Measurements (Fair70

Fair Value Measurements (Fair Value of Short-Term Investments) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carried at Amortized Cost	$ 0.8	$ 6.1
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carried at Amortized Cost	0.8	2
Fair Value	$ 0.8	$ 2

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Available-for-sale, fair value	$ 0	$ 4.1
Cost method Investments, fair value	$ 12.3	$ 12.2
1.00% Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	1.00%
2.625% Notes, Series B
Debt Instrument [Line Items]
Debt instrument, interest rate	2.625%	2.625%

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Amounts and Fair Values of Long-Term Borrowings) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Convertible notes
Carrying Amount	$ 933	$ 342.2
Fair Value	1,035.4	424.8
Long-term debt
Carrying Amount	393.6	745.8
Fair Value	$ 393.1	$ 744.8

Financial Instruments (Narrativ

Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Foreign currency transaction gain (loss), realized	$ 1.5	$ (1.2)	$ 1.4	$ (2.2)
Effects of cash flow hedges	(0.4)	$ 1.2	(1.7)	$ (1.5)
Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Notional amount	12.4		12.4
Cash Flow Hedging | Reclassification out of Accumulated Other Comprehensive Income | Cost of revenues | Effects of Cash Flow Hedges
Derivatives, Fair Value [Line Items]
Effects of cash flow hedges	2.8		6.2
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Notional amount	$ 76.6		$ 76.6		$ 145.7
Foreign currency exchange contracts | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Derivative, term of contract			12 months
Foreign currency exchange contracts | Minimum
Derivatives, Fair Value [Line Items]
Derivative, term of contract			1 month
Foreign currency exchange contracts | Maximum
Derivatives, Fair Value [Line Items]
Derivative, term of contract			3 months

Financial Instruments (Schedule

Financial Instruments (Schedule Of Net Foreign Exchange Positions) (Details) - Foreign currency exchange contracts - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Buy (Sell)	$ 4.2	$ (6.3)
Notional Amount	76.6	145.7
Euro
Derivatives, Fair Value [Line Items]
Buy (Sell)	(10.9)	(31.2)
Notional Amount	10.9	31.2
Japanese Yen
Derivatives, Fair Value [Line Items]
Buy (Sell)	(21.2)	(42.1)
Notional Amount	21.2	42.1
Malaysian Ringgit
Derivatives, Fair Value [Line Items]
Buy (Sell)	2.9	39.2
Notional Amount	2.9	39.2
Philippine Peso
Derivatives, Fair Value [Line Items]
Buy (Sell)	17.3	16.7
Notional Amount	17.3	16.7
Other Currencies - Buy
Derivatives, Fair Value [Line Items]
Buy (Sell)	20.2	13.8
Notional Amount	20.2	13.8
Other Currencies - Sell
Derivatives, Fair Value [Line Items]
Buy (Sell)	(4.1)	(2.7)
Notional Amount	$ 4.1	$ 2.7

Changes in Accumulated Other 75

Changes in Accumulated Other Comprehensive Loss (Components of Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning			$ (41.5)
Other comprehensive income (loss) prior to reclassifications			7.7
Amounts reclassified from accumulated other comprehensive loss			(10.3)
Other comprehensive (loss) income, net of tax of $0.0 million	$ (0.5)	$ 0.7	(2.6)	$ 2.8
Balance, ending	(44.1)		(44.1)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning			(42.5)
Other comprehensive income (loss) prior to reclassifications			0.2
Amounts reclassified from accumulated other comprehensive loss			0
Other comprehensive (loss) income, net of tax of $0.0 million			0.2
Balance, ending	(42.3)		(42.3)
Effects of Cash Flow Hedges
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning			(3.5)
Other comprehensive income (loss) prior to reclassifications			7.9
Amounts reclassified from accumulated other comprehensive loss			(6.2)
Other comprehensive (loss) income, net of tax of $0.0 million			1.7
Balance, ending	(1.8)		(1.8)
Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning			4.5
Other comprehensive income (loss) prior to reclassifications			(0.4)
Amounts reclassified from accumulated other comprehensive loss			(4.1)
Other comprehensive (loss) income, net of tax of $0.0 million			(4.5)
Balance, ending	$ 0		$ 0

Changes in Accumulated Other 76

Changes in Accumulated Other Comprehensive Loss (Reclassifications) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of revenues	$ 2.1	$ (1.2)	$ 7.9	$ (2.1)
Other income (expense), net	(12.6)	(9.6)	(26.5)	(26.1)
Reclassifications	46.8	40.9	154	191.9
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications	(3.5)	0.4	(10.3)	(1)
Reclassification out of Accumulated Other Comprehensive Income | Effects of Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of revenues	(2.8)	0.4	(6.2)	(1)
Reclassification out of Accumulated Other Comprehensive Income | Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income (expense), net	$ (0.7)	$ 0	$ (4.1)	$ 0

Changes in Accumulated Other 77

Changes in Accumulated Other Comprehensive Loss (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax	$ 10	$ 6.3	$ 25.1	$ (3.7)
Accumulated other comprehensive loss	(44.1)		(44.1)		$ (41.5)
Effects of Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications, tax	0		0
Accumulated other comprehensive loss	(1.8)		(1.8)		(3.5)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(42.3)		(42.3)		$ (42.5)
Foreign Currency Translation Adjustments | Subsidiaries
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (13.3)		(13.3)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax			$ 0

Supplemental Disclosures (Non-C

Supplemental Disclosures (Non-Cash Financing Activities And Cash Payments) (Details) - USD ($) $ in Millions	9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014
Non-cash activities:
Capital expenditures in accounts payable and other liabilities	$ 105.9	$ 97.4
Equipment acquired or refinanced through capital leases	2.1	6.1
Cash (received) paid for:
Interest income	(0.8)	(0.6)
Interest expense	17.9	15.2
Income taxes	$ 15	$ 15.5

Segment Information (Segment In

Segment Information (Segment Information Of Revenues, Gross Profit And Operating Income) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015USD ($)	Sep. 26, 2014USD ($)	Oct. 02, 2015USD ($)segment	Sep. 26, 2014USD ($)
Segment Reporting [Abstract]
Number of reporting segments | segment			4
Segment Reporting Information [Line Items]
Revenues	$ 904.2	$ 833.5	$ 2,655.5	$ 2,297.6
Segment gross profit	313.7	287.4	926.2	825.3
Operating Segments
Segment Reporting Information [Line Items]
Segment gross profit	313.7	287.4	926.2	825.3
Operating Segments | Application Products Group
Segment Reporting Information [Line Items]
Revenues	275.4	265.8	803.2	810.2
Segment gross profit	119.7	118.1	357	361.9
Operating Segments | Image Sensor Group
Segment Reporting Information [Line Items]
Revenues	189.4	103.6	533.1	139.9
Segment gross profit	62.8	23.4	165.5	43.5
Operating Segments | Standard Products Group
Segment Reporting Information [Line Items]
Revenues	311.6	317.3	922.6	913.9
Segment gross profit	105.5	114.9	324.6	332.1
Operating Segments | System Solutions Group
Segment Reporting Information [Line Items]
Revenues	127.8	146.8	396.6	433.6
Segment gross profit	$ 25.7	$ 31	$ 79.1	$ 87.8

Segment Information (Reconcilia

Segment Information (Reconciliations Of Segment Gross Profit And Segment Operating Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Gross profit for reportable segments	$ 313.7	$ 287.4	$ 926.2	$ 825.3
Consolidated Gross profit	308.5	280.9	913.3	807.2
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Gross profit for reportable segments	313.7	287.4	926.2	825.3
Less: unallocated manufacturing costs
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Less: unallocated manufacturing costs	$ (5.2)	$ (6.5)	$ (12.9)	$ (18.1)

Segment Information (Revenues B

Segment Information (Revenues By Geographic Location Including Local Sales And Exports) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Segment Reporting Information [Line Items]
Revenues	$ 904.2	$ 833.5	$ 2,655.5	$ 2,297.6
Reportable Geographical Components | United States
Segment Reporting Information [Line Items]
Revenues	133.5	125.5	406.1	352.6
Reportable Geographical Components | Japan
Segment Reporting Information [Line Items]
Revenues	74.5	77.4	201.9	210
Reportable Geographical Components | Hong Kong
Segment Reporting Information [Line Items]
Revenues	232.7	263.9	647.9	692.8
Reportable Geographical Components | Singapore
Segment Reporting Information [Line Items]
Revenues	270.6	210.4	881.5	580.5
Reportable Geographical Components | United Kingdom
Segment Reporting Information [Line Items]
Revenues	131.5	126.3	380.4	367
Reportable Geographical Components | Other
Segment Reporting Information [Line Items]
Revenues	$ 61.4	$ 30	$ 137.7	$ 94.7

Segment Information Segment Inf

Segment Information Segment Information (Summary of Property, Plant and Equipment by Geographic Location) (Details) - USD ($) $ in Millions	Oct. 02, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 1,256.1	$ 1,203.9
Reportable Geographical Components | United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	315.7	308.1
Reportable Geographical Components | Czech Republic
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	105	113.8
Reportable Geographical Components | Malaysia
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	227.6	232.2
Reportable Geographical Components | Philippines
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	255	197.4
Reportable Geographical Components | China
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	114	122.2
Reportable Geographical Components | Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 238.8	$ 230.2