Littelfuse (LFUS) 10-Q 1 May 19 2019 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 30, 2019	Apr. 29, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	LITTELFUSE INC /DE
Entity Central Index Key	0000889331
Current Fiscal Year End Date	--12-29
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		24,726,692
Document Type	10-Q
Document Period End Date	Mar. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018
Current assets:
Cash and cash equivalents	$ 476,614	$ 489,733
Short-term investments	33	34
Trade receivables, less allowances of $33,140 and $36,038 at March 30, 2019 and December 29, 2018, respectively	237,878	232,892
Inventories	261,659	258,228
Prepaid income taxes and income taxes receivable	758	2,339
Prepaid expenses and other current assets	53,203	49,291
Total current assets	1,030,145	1,032,517
Net property, plant, and equipment	342,334	339,894
Intangible assets, net of amortization	350,421	361,474
Goodwill	825,467	826,715
Investments	24,640	25,405
Deferred income taxes	8,461	7,330
Right of use lease assets, net	24,725
Other assets	18,825	20,971
Total assets	2,625,018	2,614,306
Current liabilities:
Accounts payable	129,092	126,323
Accrued liabilities	107,214	138,405
Accrued income taxes	23,244	20,547
Current portion of long-term debt	10,000	10,000
Total current liabilities	269,550	295,275
Long-term debt, less current portion	676,510	684,730
Deferred income taxes	52,658	51,853
Accrued post-retirement benefits	31,548	31,874
Non-current operating lease liabilities	19,950
Other long-term liabilities	69,414	72,232
Shareholders’ equity:
Common stock, par value $0.01 per share: 34,000,000 shares authorized; shares issued, March 30, 2019–25,677,535; December 29, 2018–25,641,959	254	254
Treasury stock, at cost: 950,843 and 868,045 shares, respectively	(130,103)	(116,454)
Additional paid-in capital	842,086	835,828
Accumulated other comprehensive loss	(89,851)	(97,924)
Retained earnings	882,871	856,507
Littelfuse, Inc. shareholders’ equity	1,505,257	1,478,211
Non-controlling interest	131	131
Total equity	1,505,388	1,478,342
Total liabilities and equity	$ 2,625,018	$ 2,614,306

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018
Statement of Financial Position [Abstract]
Allowance for trade receivables	$ 33,140	$ 36,038
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	34,000,000	34,000,000
Common stock issued (in shares)	25,677,535	25,641,959
Treasury stock (in shares)	950,843	868,045

Condensed Consolidated Statemen

Condensed Consolidated Statements of Net Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales	$ 405,500	$ 417,813
Cost of sales	250,272	268,190
Gross profit	155,228	149,623
Selling, general, and administrative expenses	62,955	77,514
Research and development expenses	21,409	22,540
Amortization of intangibles	10,191	11,998
Total operating expenses	94,555	112,052
Operating income	60,673	37,571
Interest expense	5,686	5,423
Foreign exchange loss (gain)	4,243	(10,555)
Other expense (income), net	4,305	(1,943)
Income before income taxes	46,439	44,646
Income taxes	9,450	8,617
Net income	$ 36,989	$ 36,029
Income per share:
Basic (in dollars per share)	$ 1.50	$ 1.48
Diluted (in dollars per share)	$ 1.48	$ 1.45
Weighted-average shares and equivalent shares outstanding:
Basic (in shares)	24,717	24,339
Diluted (in shares)	25,009	24,775

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 36,989	$ 36,029
Other comprehensive income (loss):
Pension and postemployment adjustment, net of tax	(49)	(3)
Foreign currency translation adjustments	8,122	(276)
Comprehensive income	$ 45,062	$ 35,750

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
OPERATING ACTIVITIES
Net income	$ 36,989	$ 36,029
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	13,088	11,614
Amortization of intangibles	10,191	11,998
Non-cash inventory charges	0	17,896
Stock-based compensation	3,966	8,714
Loss (gain) on investments and other assets	2,810	(1,864)
Deferred income taxes	(72)	842
Other	5,393	86
Changes in operating assets and liabilities:
Trade receivables	(5,800)	(8,417)
Inventories	(3,250)	(269)
Accounts payable	(8,499)	2,990
Accrued liabilities and income taxes	(27,170)	(7,208)
Prepaid expenses and other assets	3,273	(3,143)
Net cash provided by operating activities	30,919	69,268
INVESTING ACTIVITIES
Acquisitions of businesses, net of cash acquired	(775)	(306,487)
Purchases of property, plant, and equipment	(14,076)	(17,909)
Proceeds from sale of property, plant, and equipment	607	19
Net cash used in investing activities	(14,244)	(324,377)
FINANCING ACTIVITIES
Proceeds of revolving credit facility	0	50,000
Proceeds of term loan	0	75,000
Net proceeds from senior notes payable	0	175,000
Payments of term loan	(5,000)	(2,500)
Payments of revolving credit facility	0	(47,000)
Net proceeds (payments) related to stock-based award activities	2,198	(116)
Purchases of common stock	(17,906)	0
Debt issuance costs	0	(878)
Cash dividends paid	(10,625)	(9,198)
Net cash (used in) provided by financing activities	(31,333)	240,308
Effect of exchange rate changes on cash and cash equivalents	1,539	(2,417)
Decrease in cash and cash equivalents	(13,119)	(17,218)
Cash and cash equivalents at beginning of period	489,733	429,676
Cash and cash equivalents at end of period	476,614	412,458
Supplemental disclosure of non-cash investing activities:
Fair value of commitment to purchase non-controlling interest of Monolith	$ 0	$ 9,000

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Addl. Paid in Capital	Treasury Stock	Accum. Other Comp. Inc. (Loss)	Retained Earnings	Non- controlling Interest
Balance at Dec. 30, 2017	$ 927,556	$ 229	$ 310,012	$ (41,294)	$ (63,668)	$ 722,140	$ 137
Net income	36,029					36,029
Pension and postemployment adjustment, net of tax	(3)				(3)
Unrealized gain (loss) on investments					(9,795)	9,795
Foreign currency translation adjustments	(276)				(276)
Other comprehensive income, net of tax	(279)				(10,074)	9,795
Stock-based compensation	8,714		8,714
Withheld shares on restricted share units for withholding taxes	(2,758)			(2,758)
Stock options exercised	9,609		9,609
Issuance of common stock	472,301	22	472,279
Cash dividends paid	(9,198)					(9,198)
Balance at Mar. 31, 2018	1,441,974	251	800,614	(44,052)	(73,742)	758,766	137
Balance at Dec. 29, 2018	1,478,342	254	835,828	(116,454)	(97,924)	856,507	131
Net income	36,989					36,989
Pension and postemployment adjustment, net of tax	(49)				(49)
Foreign currency translation adjustments	8,122				8,122
Other comprehensive income, net of tax	8,073				8,073
Stock-based compensation	3,966		3,966
Withheld shares on restricted share units for withholding taxes	(94)			(94)
Stock options exercised	2,292		2,292
Repurchases of common stock	(13,555)			(13,555)
Cash dividends paid	(10,625)					(10,625)
Balance at Mar. 30, 2019	$ 1,505,388	$ 254	$ 842,086	$ (130,103)	$ (89,851)	$ 882,871	$ 131

Consolidated Statements of Equi

Consolidated Statements of Equity (Parentheticals) - $ / shares	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Cash dividends paid, per share (in dollars per share)	$ 0.43	$ 0.37

Summary of Significant Accounti

Summary of Significant Accounting Policies and Other Information	3 Months Ended
	Mar. 30, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies and Other Information	Summary of Significant Accounting Policies and Other Information Nature of Operations Littelfuse, Inc. and subsidiaries (the “Company”) is a global manufacturer of leading technologies in circuit protection, power control and sensing. The company's products are found in automotive and commercial vehicles, industrial applications, data and telecommunications, medical devices, consumer electronics and appliances. With its broad product portfolio of fuses, semiconductors, polymers, ceramics, relays and sensors, and extensive global infrastructure, the Company’s worldwide associates partner with its customers to design, manufacture and deliver innovative, high-quality solutions for a safer, greener and increasingly connected world. Basis of Presentation The Company’s accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with U.S. Generally Accepted Accounting Principles (“GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, certain information and disclosures normally included in the consolidated balance sheets, statements of net income and comprehensive income, statements of cash flows, and statement of stockholders' equity prepared in conformity with U.S. GAAP have been condensed or omitted as permitted by such rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. They have been prepared in accordance with accounting policies described in the Company’s Annual Report on Form 10-K for the fiscal year ended December 29, 2018 which should be read in conjunction with the disclosures therein. In the opinion of management, all adjustments considered necessary for a fair presentation have been included and are of a normal, recurring nature. Operating results for interim periods are not necessarily indicative of annual operating results. Revenue Recognition On December 31, 2017, the Company adopted new guidance on revenue from contracts with customers using the modified retrospective method. The adoption did not have a significant impact on the Company’s consolidated financial statements. Revenue Disaggregation The following tables disaggregate the Company’s revenue by primary business units for the three months ended March 30, 2019 and March 31, 2018 : Three Months Ended March 30, 2019 (in thousands) Electronics Segment Automotive Segment Industrial Segment Total Electronics – Passive Products and Sensors $ 108,377 $ — $ — $ 108,377 Electronics – Semiconductor 157,017 — — 157,017 Passenger Car Products — 56,543 — 56,543 Automotive Sensors — 26,057 — 26,057 Commercial Vehicle Products — 30,883 — 30,883 Industrial Products 26,623 26,623 Total $ 265,394 $ 113,483 $ 26,623 $ 405,500 Three Months Ended March 31, 2018 (in thousands) Electronics Segment Automotive Segment Industrial Segment Total Electronics – Passive Products and Sensors $ 114,495 $ — $ — $ 114,495 Electronics – Semiconductor 149,916 — — 149,916 Passenger Car Products — 63,580 — 63,580 Automotive Sensors — 31,323 — 31,323 Commercial Vehicle Products — 31,228 — 31,228 Industrial Products — 27,271 27,271 Total $ 264,411 $ 126,131 $ 27,271 $ 417,813 See Note 16, Segment Information for net sales by segment and countries. Revenue Recognition The Company recognizes revenue on product sales in the period in which the Company satisfies its performance obligation and control of the product is transferred to the customer. The Company’s sales arrangements with customers are predominately short term in nature and generally provide for transfer of control at the time of shipment as this is the point at which title and risk of loss of the product transfers to the customer. At the end of each period, for those shipments where title to the products and the risk of loss and rewards of ownership do not transfer until the product has been received by the customer, the Company adjusts revenues and cost of sales for the delay between the time that the products are shipped and when they are received by the customer. The amount of revenue recorded reflects the consideration to which the Company expects to be entitled in exchange for goods and may include adjustments for customer allowance, rebates and price adjustments. The Company’s distribution channels are primarily through direct sales and independent third-party distributors. The Company elected the practical expedient under Accounting Standards Codification ("ASC") 340-40-25-4 to expense commissions when incurred as the amortization period of the commission asset the Company would have otherwise recognized is less than one year. Revenue and Billing The Company generally accepts orders from customers through receipt of purchase orders or electronic data interchange based on written sales agreements and purchasing contracts. Contract pricing and selling agreement terms are based on market factors, costs, and competition. Pricing is often negotiated as an adjustment (premium or discount) from the Company’s published price lists. The customer is invoiced when the Company’s products are shipped to them in accordance with the terms of the sales agreement. As the Company’s standard payment terms are less than one year, the Company elected the practical expedient under ASC 606-10-32-18 to not assess whether a contract has a significant financing component. The Company also elected the practical expedient provided in ASC 606-10-25-18B to treat all product shipping and handling activities as fulfillment activities, and therefore recognize the gross revenue associated with the contract, inclusive of any shipping and handling revenue. This is similar to the Company’s prior practice and therefore the effect of the new guidance is immaterial. Ship and Debit Program Some of the terms of the Company’s sales agreements and normal business conditions provide customers (distributors) the ability to receive price adjustments on products previously shipped and invoiced. This practice is common in the industry and is referred to as a “ship and debit” program. This program allows the distributor to debit the Company for the difference between the distributors’ contracted price and a lower price for specific transactions. Under certain circumstances (usually in a competitive situation or large volume opportunity), a distributor will request authorization for pricing allowances to reduce its price. When the Company approves such a reduction, the distributor is authorized to “debit” its account for the difference between the contracted price and the lower approved price. The Company establishes reserves for this program based on historic activity and actual authorizations for the debit and recognizes these debits as a reduction of revenue. Return to Stock The Company has a return to stock policy whereby certain customers, with prior authorization from Littelfuse management, can return previously purchased goods for full or partial credit. The Company establishes an estimated allowance for these returns based on historic activity. Sales revenue and cost of sales are reduced to anticipate estimated returns. Volume Rebates The Company offers volume based sales incentives to certain customers to encourage greater product sales. If customers achieve their specific quarterly or annual sales targets, they are entitled to rebates. The Company estimates the projected amount of rebates that will be achieved by the customer and recognizes this estimated cost as a reduction to revenue as products are sold. Recently Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, "Leases" (Topic 842), ("ASC 842"). This ASU requires lessees to recognize, on the balance sheet, assets and liabilities for the rights and obligations created by leases of greater than twelve months. The accounting by lessors will remain largely unchanged. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. Adoption requires using a modified retrospective transition with either 1) periods prior to the adoption date being recast or 2) a cumulative-effect adjustment recognized to the opening balance of retained earnings on the adoption date with prior periods not recast. The Company adopted the standard on December 30, 2018 using alternative modified retrospective transition method provided in ASU No. 2018-11, "Leases (Topic 842): Target Improvements." Under this method, the Company recorded a cumulative-effect adjustment as of December 30, 2018 and did not record any retrospective adjustments to comparative periods to reflect the adoption of ASC 842. The new standard provides a number of optional practical expedients in transition. The Company has elected the ‘package of practical expedients’ which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs. The Company has not elected the use-of-hindsight. Adoption of ASC 842 resulted in the recognition of operating lease right-of-use assets ("ROU") net of deferred rent of $26.1 million and lease liabilities of $29.4 million , as of December 30, 2018 for operating leases on its Condensed Consolidated Balance Sheets, with no impact to its Condensed Consolidated Statements of Net Income and no impact on Condensed Consolidated Statements of Cash Flow. See Note 6, Lease Commitments, for further discussion. In February 2018, the FASB issued ASU No. 2018-02 “Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” which permits the reclassification of tax effects stranded in accumulated other comprehensive income to retained earnings as a result of the Tax Act. The standard also requires entities to disclose whether or not they elected to reclassify the tax effects related to the Tax Act as well as their policy for releasing income tax effects from accumulated other comprehensive income. The standard allows the option of applying either a retrospective adoption, meaning the standard is applied to all periods in which the effect of the Tax Act is recognized, or applying the amendments in the period of adoption, meaning an adjustment is made to shareholder’s equity as of the beginning of the reporting period. The Company adopted the new standard on December 30, 2018. The adoption of this guidance did not have a material effect on our Condensed Consolidated Financial Statements.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 30, 2019
Business Combinations [Abstract]
Acquisitions	Acquisitions The Company accounts for acquisitions using the acquisition method in accordance with ASC 805, “Business Combinations,” in which assets acquired and liabilities assumed are recorded at fair value as of the date of acquisition. The operating results of the acquired business are included in the Company’s Consolidated Financial Statements from the date of the acquisition. IXYS Corporation On January 17, 2018, the Company acquired IXYS Corporation (“IXYS”), a global pioneer in the power semiconductor and integrated circuit markets with a focus on medium to high voltage power control semiconductors across the industrial, communications, consumer and medical markets. IXYS has a broad customer base, serving more than 3,500 customers through its direct sales force and global distribution partners. The acquisition of IXYS is expected to accelerate the Company’s growth across the power control market driven by IXYS’s extensive power semiconductor portfolio and technology expertise. With IXYS, the Company will be able to diversify and expand its presence within industrial electronics markets, leveraging the strong IXYS industrial OEM customer base. The Company also expects to increase long-term penetration of its power semiconductor portfolio in automotive markets, expanding its global content per vehicle. Upon completion of the acquisition, at IXYS stockholders’ election and subject to proration, each share of IXYS common stock, par value $0.01 per share, owned immediately prior to the effective time was canceled and extinguished and automatically converted into the right to receive: (i) $23.00 in cash (subject to applicable withholding tax), without interest (referred to as the cash consideration), or (ii) 0.1265 of a share of common stock, par value $0.01 per share, of Littelfuse (referred to as the stock consideration). IXYS stockholders received cash in lieu of any fractional shares of Littelfuse common stock that the IXYS stockholders would otherwise have been entitled to receive. Additionally, each outstanding option to purchase shares of IXYS common stock granted under an IXYS equity plan were assumed by Littelfuse and converted into an option to acquire (i) a number of shares of Littelfuse common stock equal to the number of shares of IXYS common stock subject to such option immediately prior to the effective time multiplied by 0.1265 , rounded down to the nearest whole share, with (ii) an exercise price per share of Littelfuse common stock equal to the exercise price of such IXYS stock option immediately prior to the effective time divided by 0.1265 , rounded up to the nearest whole cent. Based on the $207.5 per share opening price of Littelfuse common stock on January 17, 2018, the consideration IXYS stockholders received in exchange of their IXYS common stock in the acquisition had a value of $814.8 million comprised of $380.6 million of cash and $434.2 million of Littelfuse stock. In addition to the consideration transferred related to IXYS common stock, the value of consideration transferred, and included in the purchase price, related to IXYS stock options that were converted to Littelfuse stock options, or cash settled, had a value of $41.7 million . As a result, total consideration was valued at $856.5 million . The total purchase price of $856.5 million has been allocated to assets acquired and liabilities assumed, as of the completion of the acquisition, based on estimated fair values. The following table summarizes the purchase price allocation of the fair value of assets acquired and liabilities assumed in the IXYS acquisition: (in thousands) Purchase Price Allocation Total purchase consideration: Cash, net of cash acquired $ 302,865 Cash settled stock options 3,622 Littelfuse stock 434,192 Converted stock options 38,109 Total purchase consideration $ 778,788 Allocation of consideration to assets acquired and liabilities assumed: Current assets, net $ 155,930 Property, plant, and equipment 77,442 Intangible assets 212,720 Goodwill 382,360 Other non-current assets 28,706 Other non-current liabilities (78,370 ) $ 778,788 Approximately $49.1 million of net receivables was included in IXYS’s current assets. All IXYS goodwill, other assets and liabilities were recorded in the Electronics segment and primarily reflected in the Americas and European geographic areas. The goodwill resulting from this acquisition consists largely of the Company’s expected future product sales and synergies from combining IXYS’s products and technology with the Company’s existing electronics product portfolio. Goodwill resulting from the IXYS acquisition is not expected to be deductible for tax purposes. During the three months ended March 31, 2018, the Company recognized a charge of $17.9 million for the amortization of the fair value inventory step-up. The step-up was a non-cash charge to cost of goods and reflected as other non-segment costs. The Company recognized approximately $5.9 million of stock compensation expense related to IXYS stock options converted to Littelfuse stock options during the three months ended March 31, 2018 of which $4.5 million was recognized immediately as it related to prior services periods. During the three months ended March 31, 2018, the Company incurred approximately $10.2 million of legal and professional fees related to this acquisition which were primarily recognized as selling, general, and administrative expenses . These costs were reflected as other non-segment costs. Pro Forma Results The following table summarizes, on a pro forma basis, the combined results of operations of the Company and IXYS as though the acquisition had occurred as of January 1, 2017. The pro forma amounts presented are not necessarily indicative of either the actual consolidated results had the IXYS acquisition occurred as of January 1, 2017 or of future consolidated operating results. Three Months Ended (in thousands, except per share amounts) March 31, 2018 Net sales $ 434,526 Income before income taxes 81,924 Net income 63,933 Net income per share — basic 2.57 Net income per share — diluted 2.53 Pro forma results presented above primarily reflect the following adjustments: Three Months Ended (in thousands) March 31, 2018 Amortization (a) $ 1,902 Transaction costs (b) 9,976 Amortization of inventory step-up (c) 17,896 Stock compensation (d) 4,479 Income tax impact of above items (7,701 ) (a) The amortization adjustment for the three months ended March 31, 2018 primarily reflects the reduction of amortization expense in the period related to the Order backlog intangible asset. The Order backlog has a useful life of twelve months and was fully amortized in the fiscal 2017 pro forma results. (b) The transaction cost adjustments reflect the reversal of certain bank and attorney fees from the three months ended March 31, 2018 and recognition of those fees during the three months ended April 1, 2017. (c) The amortization of inventory step-up adjustment reflects the reversal of the amount recognized during the three months ended March 31, 2018 and recognition of those fees during the three months ended April 1, 2017. The inventory step-up was amortized over five months as the inventory was sold. (d) The stock compensation adjustment reflects the reversal of the portion of stock compensation for IXYS stock options that were converted to Littelfuse stock options and expensed immediately during the three months ended March 31, 2018 .

Inventories

Inventories	3 Months Ended
	Mar. 30, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories The components of inventories at March 30, 2019 and December 29, 2018 are as follows: (in thousands) March 30 December 29 Raw materials $ 75,949 $ 69,883 Work in process 90,538 88,505 Finished goods 95,172 99,840 Total $ 261,659 $ 258,228

Property, Plant, and Equipment

Property, Plant, and Equipment	3 Months Ended
	Mar. 30, 2019
Property, Plant and Equipment [Abstract]
Property, Plant, and Equipment	Property, Plant, and Equipment The components of net property, plant, and equipment at March 30, 2019 and December 29, 2018 are as follows: (in thousands) March 30 December 29 Land $ 25,607 $ 25,630 Building 114,506 114,636 Equipment 599,254 583,043 Accumulated depreciation and amortization (397,033 ) (383,415 ) Total $ 342,334 $ 339,894 The Company recorded depreciation expense of $13.1 million and $11.6 million for the three months ended March 30, 2019 and March 31, 2018 , respectively.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The amounts for goodwill and changes in the carrying value by segment for the three months ended March 30, 2019 are as follows: (in thousands) Electronics Automotive Industrial Total As of December 29, 2018 $ 656,039 $ 132,332 $ 38,344 $ 826,715 Currency translation (1,400 ) 102 50 (1,248 ) As of March 30, 2019 $ 654,639 $ 132,434 $ 38,394 $ 825,467 The components of other intangible assets at March 30, 2019 are as follows: (in thousands, except weighted average useful life) Weighted Average Useful Life (Years) Gross Carrying Value Accumulated Amortization Net Book Value Patents, licenses and software 11.1 $ 138,951 $ 72,219 $ 66,732 Distribution network 12.3 43,797 35,049 8,748 Customer relationships, trademarks, and tradenames 17.2 374,204 99,263 274,941 Total $ 556,952 $ 206,531 $ 350,421 During the three months ended March 30, 2019 and March 31, 2018 , the Company recorded amortization expense of $10.2 million and $12.0 million , respectively, for intangible assets with definite lives. Estimated annual amortization expense related to intangible assets with definite lives as of March 30, 2019 is as follows: (in thousands) Amount 2019 $ 49,524 2020 38,776 2021 36,930 2022 35,884 2023 30,423 2024 and thereafter 169,075 Total $ 360,612

Lease Commitments

Lease Commitments	3 Months Ended
	Mar. 30, 2019
Leases [Abstract]
Lease Commitments	Lease Commitments The Company leases office and production space under various non-cancelable operating leases that expire no later than 2025. Certain real estate leases include one or more options to renew. The exercise of lease renewal options is at the Company's sole discretion. Options to extend the lease are included in the lease term when it is reasonably certain the Company will exercise the option.The Company also has production equipment, office equipment and vehicles under operating leases. The depreciable life of assets and leasehold improvements are limited by the expected lease term, unless there is a transfer of title or purchase option that is reasonably certain of exercise. Certain leases include rental payments adjusted periodically for inflation. The lease agreements do not contain any material residual value guarantee or material restrictive covenants. The Company does not have a published credit rating because it has no publicly traded debt; therefore, the Company is generating its incremental borrowing rate (IBR), using a synthetic credit rating model that compares its credit quality to other rated companies based on certain financial metrics and ratios. The reference rate will be based on the yield curve of companies with similar credit quality based on the metrics and adjusted for currency in regions where we have significant operations. All leases with an initial term of 12 months or less that do not include an option to extend or purchase the underlying asset that the Company is reasonably certain to exercise (“short-term leases”) are not recorded on the Condensed Consolidated Balance Sheet. Short-term lease expenses are recognized on a straight-line basis over the lease term. The following table presents the classification of ROU assets and lease liabilities as of March 30, 2019 : Leases (in thousands) Condensed Consolidated Balance Sheet Classification March 30, 2019 Assets Operating ROU assets Right of use lease assets, net $ 24,725 Liabilities Current operating lease liabilities Accrued liabilities $ 7,447 Non-current operating lease liabilities Non-current operating lease liabilities 19,950 Total lease liabilities $ 27,397 The following table represents the lease costs for the three months ended March 30, 2019 : Leases cost (in thousands) Condensed Consolidated Statements of Net Income Classification March 30, 2019 Short-term lease expenses Cost of sales, SG&A expenses $ 153 Variable lease expenses Cost of sales, SG&A expenses 194 Operating lease rent expenses Cost of sales, SG&A expenses 2,193 Total operating lease costs Cost of sales, SG&A expenses $ 2,540 Maturity of Lease Liabilities as of March 30, 2019 (in thousands) Operating leases 2019 (excluding the three months ended March 30, 2019) $ 6,574 2020 7,551 2021 5,779 2022 4,665 2023 3,062 2024 and thereafter 3,064 Total lease payments $ 30,695 Present value of lease Liabilities $ 27,397 Operating Lease Term and Discount Rate March 30, 2019 Weighted-average remaining lease term (years) 4.40 Weighted-average discount rate 5.17 % Other Information (in thousands) Three Months Ended Cash paid for amounts included in the measurement of lease liabilities Operating cash flow payments for operating leases $ (2,253 ) Leased assets obtained in exchange for operating lease liabilities 859

Accrued Liabilities

Accrued Liabilities	3 Months Ended
	Mar. 30, 2019
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities The components of accrued liabilities at March 30, 2019 and December 29, 2018 are as follows: (in thousands) March 30, 2019 December 29, 2018 Employee-related liabilities $ 38,479 $ 60,640 Other non-income taxes 25,379 21,523 Operating lease liability 7,447 — Professional services 5,395 6,169 Interest 2,487 5,137 Accrued share repurchases — 4,349 Restructuring liability 2,144 3,887 Other 25,883 36,700 Total $ 107,214 $ 138,405 Employee-related liabilities consist primarily of payroll, sales commission, bonus, employee benefit accruals and workers’ compensation. Bonus accruals include amounts earned pursuant to the Company’s primary employee incentive compensation plans. Other accrued liabilities include miscellaneous operating accruals and other client-related liabilities.

Restructuring, Impairment and O

Restructuring, Impairment and Other Charges	3 Months Ended
	Mar. 30, 2019
Restructuring and Related Activities [Abstract]
Restructuring, Impairment and Other Charges	Restructuring, Impairment and Other Charges The Company recorded restructuring, impairment and other charges-net for three months ended March 30, 2019 and March 31, 2018 as follows: Three months ended March 30, 2019 (in thousands) Electronics Automotive Industrial Total Employee terminations $ 1,800 $ 605 $ 47 $ 2,452 Other restructuring charges 13 20 250 283 Total restructuring charges $ 1,813 $ 625 $ 297 $ 2,735 Three months ended March 31, 2018 (in thousands) Electronics Automotive Industrial Total Employee terminations $ 677 $ 99 $ 3 $ 779 Total restructuring charges $ 677 $ 99 $ 3 $ 779 2019 For the three months ended March 30, 2019, the Company recorded total restructuring charges of $2.7 million , of which $2.5 million was for employee termination costs and $0.3 million for other restructuring charges. These charges primarily related to reorganization of operations and selling, general and administrative functions as well as integration of IXYS within the Electronics segment and the reorganization of operations in the commercial vehicle products and automotive sensors businesses within the Automotive segment. In April 2019, we announced the closure of a European manufacturing facility in the automotive sensors business within the Automotive segment. The Company estimates the restructuring costs associated with this plant closure to be approximately $5.0 million to $7.0 million . 2018 For the three months ended March 31, 2018, the Company recorded total restructuring charges of $0.8 million for employee termination costs mainly related to the Electronics segment. The restructuring reserves as of March 30, 2019 and December 29, 2018 are $2.1 million and $3.9 million , respectively. The restructuring reserves are included within accrued liabilities in the Condensed Consolidated Balance Sheets. The Company anticipates the remaining payments associated with employee terminations will be completed in the second quarter of fiscal year 2019.

Debt

Debt	3 Months Ended
	Mar. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt The carrying amounts of debt at March 30, 2019 and December 29, 2018 are as follows: (in thousands) March 30, December 29, Term Loan $ 150,000 $ 155,000 Euro Senior Notes, Series A due 2023 131,499 133,417 Euro Senior Notes, Series B due 2028 106,772 108,330 U.S. Senior Notes, Series A due 2022 25,000 25,000 U.S. Senior Notes, Series B due 2027 100,000 100,000 U.S. Senior Notes, Series A due 2025 50,000 50,000 U.S. Senior Notes, Series B due 2030 125,000 125,000 Other 2,619 2,619 Unamortized debt issuance costs (4,380 ) (4,636 ) Total debt 686,510 694,730 Less: Current maturities (10,000 ) (10,000 ) Total long-term debt $ 676,510 $ 684,730 Revolving Credit Facility / Term Loan On March 4, 2016, the Company entered into a five -year credit agreement (“Credit Agreement”) with a group of lenders for up to $700.0 million . The Credit Agreement consisted of an unsecured revolving credit facility (“Revolving Credit Facility”) of $575.0 million and an unsecured term loan credit facility (“Term Loan”) of up to $125.0 million . In addition, the Company had the ability, from time to time, to increase the size of the Revolving Credit Facility and the Term Loan by up to an additional $150.0 million , in the aggregate, in each case in minimum increments of $25.0 million , subject to certain conditions and the agreement of participating lenders. On October 13, 2017, the Company amended the Credit Agreement to increase the Revolving Credit Facility from $575.0 million to $700.0 million and increase the Term Loan from $125.0 million to $200.0 million and to extend the expiration date from March 4, 2021 to October 13, 2022. The Credit Agreement also includes the option for the Company to increase the size of the Revolving Credit Facility and the Term Loan by up to an additional $300.0 million , in the aggregate, subject to the satisfaction of certain conditions set forth in the Credit Agreement. Term Loans may be made in up to two advances. The first advance of $125.0 million occurred on October 13, 2017 and the second advance of $75.0 million occurred on January 16, 2018. For the Term Loan, the Company is required to make quarterly principal payments of 1.25% of the original term loan ( $2.5 million with the second advance on January 16, 2018) through maturity, with the remaining balance due on October 13, 2022. The Company paid quarterly principal payments of $5.0 million on the term loan during the three months ended March 30, 2019 . Outstanding borrowings under the Credit Agreement bear interest, at the Company’s option, at either LIBOR, fixed for interest periods of one , two , three or six -month periods, plus 1.00% to 2.00% , or at the bank’s Base Rate, as defined, plus 0.00% to 1.00% , based upon the Company’s Consolidated Leverage Ratio, as defined. The Company is also required to pay commitment fees on unused portions of the credit agreement ranging from 0.15% to 0.25% , based on the Consolidated Leverage Ratio, as defined in the agreement. The credit agreement includes representations, covenants and events of default that are customary for financing transactions of this nature. The effective interest rate on outstanding borrowings under the credit facility was 3.75% at March 30, 2019 . As of March 30, 2019 , the Company had $0.1 million outstanding in letters of credit and had available $699.9 million of borrowing capacity under the Revolving Credit Facility. At March 30, 2019 , the Company was in compliance with all covenants under the Credit Agreement. Senior Notes On December 8, 2016, the Company entered into a Note Purchase Agreement, pursuant to which the Company issued and sold €212 million aggregate principal amount of senior notes in two series. The funding date for the Euro denominated senior notes occurred on December 8, 2016 for €117 million in aggregate amount of 1.14% Senior Notes, Series A, due December 8, 2023 (“Euro Senior Notes, Series A due 2023”), and €95 million in aggregate amount of 1.83% Senior Notes, Series B due December 8, 2028 (“Euro Senior Notes, Series B due 2028”) (together, the “Euro Senior Notes”). Interest on the Euro Senior Notes is payable semiannually on June 8 and December 8, commencing June 8, 2017. On December 8, 2016, the Company entered into a Note Purchase Agreement, pursuant to which the Company issued and sold $125 million aggregate principal amount of senior notes in two series. On February 15, 2017, $25 million in aggregate principal amount of 3.03% Senior Notes, Series A, due February 15, 2022 (“U.S. Senior Notes, Series A due 2022”), and $100 million in aggregate principal amount of 3.74% Senior Notes, Series B, due February 15, 2027 (“U.S. Senior Notes, Series B due 2027”) (together, the “U.S. Senior Notes due 2022 and 2027”) were funded. Interest on the U.S. Senior Notes due 2022 and 2027 is payable semiannually on February 15 and August 15, commencing August 15, 2017. On November 15, 2017, the Company entered into a Note Purchase Agreement pursuant to which the Company issued and sold $175 million in aggregate principal amount of senior notes in two series. On January 16, 2018, $50 million aggregate principal amount of 3.48% Senior Notes, Series A, due February 15, 2025 (“U.S. Senior Notes, Series A due 2025”) and $125 million in aggregate principal amount of 3.78% Senior Notes, Series B, due February 15, 2030 (“U.S. Senior Notes, Series B due 2030”) (together the “U.S. Senior Notes due 2025 and 2030” and with the Euro Senior Notes and the U.S. Senior Notes due 2022 and 2027, the “Senior Notes”) were funded. Interest on the U.S. Senior Notes due 2025 and 2030 is payable semiannually on February 15 and August 15, commencing on August 15, 2018. The Senior Notes have not been registered under the Securities Act, or applicable state securities laws. The Senior Notes are general unsecured senior obligations and rank equal in right of payment with all existing and future unsecured unsubordinated indebtedness of the Company. The Senior Notes are subject to certain customary covenants, including limitations on the Company’s ability, with certain exceptions, to engage in mergers, consolidations, asset sales and transactions with affiliates, to engage in any business that would substantially change the general business of the Company, and to incur liens. In addition, the Company is required to satisfy certain financial covenants and tests relating to, among other matters, interest coverage and leverage. At March 30, 2019 , the Company was in compliance with all covenants under the Senior Notes. The Company may redeem the Senior Notes upon the satisfaction of certain conditions and the payment of a make-whole amount to noteholders, and are required to offer to repurchase the Senior Notes at par following certain events, including a change of control. Interest paid on all Company debt was $8.0 million and $4.0 million in the three months ended March 30, 2019 and March 31, 2018 , respectively.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	3 Months Ended
	Mar. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities For assets and liabilities measured at fair value on a recurring and nonrecurring basis, a three-level hierarchy of measurements based upon observable and unobservable inputs is used to arrive at fair value. Observable inputs are developed based on market data obtained from independent sources, while unobservable inputs reflect the Company’s assumptions about valuation based on the best information available in the circumstances. Depending on the inputs, the Company classifies each fair value measurement as follows: Level 1 —Valuations based on unadjusted quoted prices for identical assets or liabilities in active markets; Level 2 —Valuations based upon quoted prices for similar instruments, prices for identical or similar instruments in markets that are not active, or model-derived valuations, all of whose significant inputs are observable, and Level 3 —Valuations based upon one or more significant unobservable inputs. Following is a description of the valuation methodologies used for instruments measured at fair value and their classification in the valuation hierarchy. Investments in Equity Securities Investments in equity securities listed on a national market or exchange are valued at the last sales price and classified within Level 1 of the valuation hierarchy and recorded in investments and other assets. The Company has certain convertible debt and convertible preferred stock investments that are accounted for under the cost method reflected in other assets in the Condensed Consolidated Balance Sheets. During the three months ended March 30, 2019 , the Company recorded impairment charges of $2.8 million in Other expense (income), net in the Condensed Consolidated Statements of Net Income to adjust these certain investments to their estimated fair value of $1.2 million . The fair value of these investments are measured on a nonrecurring basis and determined to be Level 3 under the fair value hierarchy. The Company's accounting and finance management determines the valuation policies and procedures for Level 3 fair value measurements and is responsible for the development and determination of unobservable inputs. Mutual Funds The Company has a non-qualified Supplemental Retirement and Savings Plan which provides additional retirement benefits for certain management employees and named executive officers by allowing participants to defer a portion of their annual compensation. The Company maintains accounts for participants through which participants make investment elections. The marketable securities are classified as Level 1 under the fair value hierarchy as they are maintained in mutual funds with readily determinable fair value and recorded in other assets. There were no changes during the quarter ended March 30, 2019 to the Company’s valuation techniques used to measure asset and liability fair values on a recurring basis. As of March 30, 2019 and December 29, 2018 , the Company did not hold any non-financial assets or liabilities that are required to be measured at fair value on a recurring basis. The following table presents assets measured at fair value by classification within the fair value hierarchy as of March 30, 2019 : Fair Value Measurements Using (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Investments in equity securities $ 10,551 $ — $ — $ 10,551 Mutual funds 9,806 — — 9,806 The following table presents assets measured at fair value by classification within the fair value hierarchy as of December 29, 2018 : Fair Value Measurements Using (in thousands) Quoted Prices in Significant Significant Total Investments in equity securities $ 10,312 $ — $ — $ 10,312 Mutual funds 9,112 — — 9,112 In addition to the methods and assumptions used for the financial instruments recorded at fair value as discussed above, the following methods and assumptions are used to estimate the fair value of other financial instruments that are not marked to market on a recurring basis. The Company’s other financial instruments include cash and cash equivalents, short-term investments, accounts receivable and its long-term debt. Due to their short-term maturity, the carrying amounts of cash and cash equivalents, short-term investments and accounts receivable approximate their fair values. The Company’s revolving and term loan debt facilities’ fair values approximate book value at March 30, 2019 and December 29, 2018 , as the rates on these borrowings are variable in nature. The carrying value and estimated fair values of the Company’s Euro Senior Notes, Series A and Series B and USD Senior Notes, Series A and Series B, as of March 30, 2019 and December 29, 2018 were as follows: March 30, 2019 December 29, 2018 (in thousands) Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Euro Senior Notes, Series A due 2023 $ 131,499 $ 129,800 $ 133,417 $ 130,888 Euro Senior Notes, Series B due 2028 106,772 105,700 108,330 103,774 USD Senior Notes, Series A due 2022 25,000 24,374 25,000 24,115 USD Senior Notes, Series B due 2027 100,000 96,673 100,000 94,458 USD Senior Notes, Series A due 2025 50,000 48,349 50,000 47,434 USD Senior Notes, Series B due 2030 125,000 118,090 125,000 114,731

Benefit Plans

Benefit Plans	3 Months Ended
	Mar. 30, 2019
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans The Company has company-sponsored defined benefit pension plans covering employees in the U.K., Germany, the Philippines, China, Japan, Mexico, Italy and France. The amount of the retirement benefits provided under the plans is based on years of service and final average pay. The Company recognizes interest cost, expected return on plan assets, and amortization of prior service, net within Other expense (income), net in the Condensed Consolidated Statements of Net Income. The components of net periodic benefit cost for the three months ended March 30, 2019 and March 31, 2018 were as follows: For the Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Components of net periodic benefit cost: Service cost $ 500 $ 533 Interest cost 784 501 Expected return on plan assets (790 ) (540 ) Amortization of prior service 62 74 Net periodic benefit cost $ 556 $ 568 The Company expects to make approximately $2.3 million of cash contributions to its pension plans in 2019.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 30, 2019
Equity [Abstract]
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Change in other comprehensive (loss) income by component were as follows: (in thousands) Three Months Ended March 30, 2019 Three Months Ended March 31, 2018 Pre-tax Tax Net of Tax Pre-tax Tax Net of Tax Defined benefit pension plan adjustments $ (78 ) $ (29 ) $ (49 ) $ (68 ) $ (65 ) $ (3 ) Foreign currency translation adjustments 8,122 — 8,122 (276 ) — (276 ) Total change in other comprehensive income (loss) $ 8,044 $ (29 ) $ 8,073 $ (344 ) $ (65 ) $ (279 ) The following tables set forth the changes in accumulated other comprehensive (loss) income by component for the three months ended March 30, 2019 and March 31, 2018 : (in thousands) Pension and postretirement liability and reclassification adjustments Foreign currency translation adjustment Accumulated other comprehensive income (loss) Balance at December 29, 2018 $ (9,959 ) $ (87,965 ) $ (97,924 ) Activity in the period (49 ) 8,122 8,073 Balance at March 30, 2019 $ (10,008 ) $ (79,843 ) $ (89,851 ) (in thousands) Pension and postretirement liability and reclassification adjustments Unrealized gain (loss) on investments Foreign currency translation adjustment Accumulated other comprehensive income (loss) Balance at December 30, 2017 $ (10,836 ) $ 9,795 $ (62,627 ) $ (63,668 ) Cumulative effect adjustment (a) — (9,795 ) — (9,795 ) Activity in the period (3 ) — (276 ) (279 ) Balance at March 31, 2018 $ (10,839 ) $ — $ (62,903 ) $ (73,742 ) (a)The Company adopted ASU 2016-01 on December 31, 2017 on a modified retrospective basis, recognizing the cumulative effect as a $9.8 million increase to retained earnings. Amounts reclassified from accumulated other comprehensive (loss) income to earnings for the three months ended March 30, 2019 and March 31, 2018 were as follows: Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Pension and Postemployment plans: Amortization of prior service $ 62 $ 74 The Company recognizes the amortization of prior service costs in Other (expense) income, net within the Condensed Consolidated Statements of Net Income.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate for the three months ended March 30, 2019 was 20.3% , compared to an effective tax rate for the three months ended March 31, 2018 of 19.3% . The effective tax rates for both periods were lower than the applicable U.S. statutory tax rate primarily due to income earned in lower tax jurisdictions.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table sets forth the computation of basic and diluted earnings per share: Three Months Ended (in thousands, except per share amounts) March 30, 2019 March 31, 2018 Numerator: Net income as reported $ 36,989 $ 36,029 Denominator: Weighted average shares outstanding Basic 24,717 24,339 Effect of dilutive securities 292 436 Diluted 25,009 24,775 Earnings Per Share: Basic earnings per share $ 1.50 $ 1.48 Diluted earnings per share $ 1.48 $ 1.45 Potential shares of common stock relating to stock options excluded from the earnings per share calculation because their effect would be anti-dilutive were 77,047 for the three months ended March 30, 2019 . No potential shares of common stock attributable to stock options were excluded from the diluted earnings per share calculation for the three months ended March 31, 2018 . Share Repurchase Program The Company’s Board of Directors authorized the repurchase of up to 1,000,000 shares of the Company’s common stock under a program for the period May 1, 2018 to April 30, 2019. On April 26, 2019, the Company's Board of Directors authorized a new program to repurchase up to 1,000,000 shares of the Company's common stock for the period May 1, 2019 to April 30, 2020. During the three months ended March 30, 2019 , the Company repurchased 79,916 shares of its common stock totaling $13.6 million .

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions As a result of the Company’s acquisition of IXYS, the Company has equity ownership in various investments that are accounted for under the equity method and recorded in investments in the Condensed Consolidated Balance Sheets. The following is a description of the investments and related party transactions. Powersem GmbH: The Company owns 45% of the outstanding equity of Powersem GmbH (“Powersem”), a module manufacturer based in Germany. For both the three months ended March 30, 2019 and March 31, 2018, the Company recorded revenues of $0.1 million from sales of products to Powersem for use as components in their products. During the three months ended March 30, 2019 and March 31, 2018 , the Company purchased $0.8 million and $1.1 million of products from Powersem, respectively. As of March 30, 2019 , the accounts receivable balance from Powersem was $0.1 million and the accounts payable balance to Powersem was $0.1 million . As of December 29, 2018, the trade receivable balance from Powersem was $0.1 million and the accounts payable balance to Powersem was $0.2 million . EB Tech Ltd.: The Company owns approximately 20% of the outstanding equity of EB Tech Ltd. (“EB Tech”), a company with expertise in radiation technology based in South Korea. EB Tech rendered processing services for the Company totaling approximately $0.1 million for both three months ended March 30, 2019 and March 31, 2018 . As of March 30, 2019 and December 29, 2018, the Company’s accounts payable balance to EB Tech was $0.1 million . Automated Technology, Inc. : The Company owns approximately 24% of the outstanding common shares of Automated Technology, Inc (“ATEC”), a supplier located in the Philippines that provides assembly and test services. During the three months ended March 30, 2019 and March 31, 2018 , ATEC rendered assembly and test services to the Company totaling approximately $1.5 million and $2.4 million , respectively. As of March 30, 2019 , the Company’s accounts payable balance to ATEC was $0.4 million . As of December 29, 2018, the Company’s accounts payable balance to ATEC was $0.5 million . On March 25, 2019, the Company entered into a definitive agreement to sell the assets and liabilities of Microwave Technology, Inc. (“MWT”) resulting in a loss on disposal of $2.6 million reflected in Other income (expense), net in the Condensed Consolidated Statements of Net Income. The operations of Microwave Technology, Inc. were included in the Electronics segment. One member of the Company’s Board of Directors is the co-owner of a company that agreed to purchase MWT. This transaction closed on April 26, 2019.

Segment Information

Segment Information	3 Months Ended
	Mar. 30, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information The Company and its subsidiaries design, manufacture and sell components and modules for circuit protection, power control and sensing throughout the world. The Company reports its operations by the following segments: Electronics, Automotive, and Industrial. An operating segment is defined as a component of an enterprise that engages in business activities from which it may earn revenues and incur expenses, and about which separate financial information is regularly evaluated by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources. The CODM is the Company’s President and Chief Executive Officer (“CEO”). The CODM allocates resources to and assesses the performance of each operating segment using information about its revenue and operating income (loss) before interest and taxes, but does not evaluate the operating segments using discrete balance sheet information. Sales, marketing, and research and development expenses are charged directly into each operating segment. Manufacturing, purchasing, logistics, customer service, finance, information technology, and human resources are shared functions that are allocated back to the three operating segments. The Company does not report inter-segment revenue because the operating segments do not record it. Certain expenses, determined by the CODM to be strategic in nature and not directly related to segments current results, are not allocated but identified as “Other”. Additionally, the Company does not allocate interest and other income, interest expense, or taxes to operating segments. These costs are not allocated to the segments, as management excludes such costs when assessing the performance of the segments. Although the CODM uses operating income (loss) to evaluate the segments, operating costs included in one segment may benefit other segments. Except as discussed above, the accounting policies for segment reporting are the same as for the Company as a whole. • Electronics Segment : Consists of one of the broadest product offerings in the industry, including fuses and fuse accessories, positive temperature coefficient (“PTC”) resettable fuses, polymer electrostatic discharge (“ESD”) suppressors, varistors, reed switch based magnetic sensing, gas discharge tubes; semiconductor and power semiconductor products such as discrete transient voltage suppressor (“TVS”) diodes, TVS diode arrays, protection and switching thyristors, silicon carbide, metal-oxide-semiconductor field-effect transistors (“MOSFETs”) and silicon carbide diodes; and insulated gate bipolar transistors (“IGBT”) technologies. The segment covers a broad range of end markets, including industrial and automotive electronics, electric vehicle infrastructure, data and telecommunications, medical devices, LED lighting, consumer electronics and appliances • Automotive Segment: Consists of a wide range of circuit protection, power control and sensing technologies for global original equipment manufacturers (“OEMs”), Tier-I suppliers and parts distributors in passenger car, heavy duty truck, off-road vehicles, material handling, agricultural, construction and other commercial vehicle industries. Passenger car fuse products include fuses and fuse accessories for internal combustion engine vehicles and hybrid and electric vehicles including blade fuses, battery cable protectors, resettable fuses, high-current fuses, and high-voltage fuses. Commercial vehicle products include fuses, switches, relays, and power distribution modules for the commercial vehicle industry. Automotive sensor products include a wide range of automotive and commercial vehicle products designed to monitor the passenger compartment occupants, safety and environment as well as the vehicle’s powertrain, emissions, speed and suspension. • Industrial Segment: Consists of power fuses, protection relays and controls and other circuit protection products for use in various industrial applications such as oil, gas, mining, alternative energy - solar and wind, electric vehicle infrastructure, construction, HVAC systems, elevator and other industrial equipment. Segment information is summarized as follows: Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Net sales Electronics $ 265,394 $ 264,411 Automotive 113,483 126,131 Industrial 26,623 27,271 Total net sales $ 405,500 $ 417,813 Depreciation and amortization Electronics $ 15,342 $ 13,678 Automotive 6,877 5,970 Industrial 1,060 1,460 Other — 2,504 Total depreciation and amortization $ 23,279 $ 23,612 Operating income (loss) Electronics $ 49,037 $ 53,964 Automotive 13,200 18,390 Industrial 3,505 4,709 Other (a) (5,069 ) (39,492 ) Total operating income 60,673 37,571 Interest expense 5,686 5,423 Foreign exchange loss (gain) 4,243 (10,555 ) Other expense (income), net 4,305 (1,943 ) Income before income taxes $ 46,439 $ 44,646 (a) Included in “Other” Operating income (loss) for the 2019 first quarter is $2.4 million of acquisition integration charges primarily related to the IXYS acquisition. In addition, there were $2.7 million of restructuring charges primarily related to employee termination costs. The first quarter of 2018 includes approximately $38.6 million of charges primarily related to the IXYS acquisition, which include $17.9 million of purchase accounting inventory step-up charges, $11.6 million in acquisition-related and integration costs primarily related to legal, accounting and other expenses, $2.5 million in backlog amortization costs, and $4.5 million in stock compensation expense recognized immediately upon close for converted IXYS options related to prior service periods and $2.1 million change in control expense related to IXYS. In addition, there were $0.8 million of employee termination costs and $0.1 million of acquisition-related expenses for other contemplated acquisitions. The Company’s net sales by country were as follows: Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Net sales United States $ 119,528 $ 123,877 China 57,334 106,508 Other countries (a) 228,638 187,428 Total net sales $ 405,500 $ 417,813 The Company’s long-lived assets by country were as follows: (in thousands) March 30, December 29, Long-lived assets United States $ 57,527 $ 58,691 China 94,807 95,806 Mexico 73,694 70,495 Germany 35,536 36,548 Philippines 36,223 32,459 Other countries (a) 44,547 45,895 Total long-lived assets $ 342,334 $ 339,894 The Company’s additions to long-lived assets by country were as follows: Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Additions to long-lived assets United States $ 905 $ 2,909 China 1,225 5,144 Mexico 5,484 3,310 Germany 598 3,038 Philippines 5,229 2,162 Other countries (a) 635 1,346 Total additions to long-lived assets $ 14,076 $ 17,909 (a) Each country included in other countries are less than 10% of net sales.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and Other Information (Policies)	3 Months Ended
	Mar. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with U.S. Generally Accepted Accounting Principles (“GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, certain information and disclosures normally included in the consolidated balance sheets, statements of net income and comprehensive income, statements of cash flows, and statement of stockholders' equity prepared in conformity with U.S. GAAP have been condensed or omitted as permitted by such rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. They have been prepared in accordance with accounting policies described in the Company’s Annual Report on Form 10-K for the fiscal year ended December 29, 2018 which should be read in conjunction with the disclosures therein. In the opinion of management, all adjustments considered necessary for a fair presentation have been included and are of a normal, recurring nature. Operating results for interim periods are not necessarily indicative of annual operating results.
Revenue Recognition	Revenue Recognition On December 31, 2017, the Company adopted new guidance on revenue from contracts with customers using the modified retrospective method. The adoption did not have a significant impact on the Company’s consolidated financial statements. Revenue Disaggregation The following tables disaggregate the Company’s revenue by primary business units for the three months ended March 30, 2019 and March 31, 2018 : Three Months Ended March 30, 2019 (in thousands) Electronics Segment Automotive Segment Industrial Segment Total Electronics – Passive Products and Sensors $ 108,377 $ — $ — $ 108,377 Electronics – Semiconductor 157,017 — — 157,017 Passenger Car Products — 56,543 — 56,543 Automotive Sensors — 26,057 — 26,057 Commercial Vehicle Products — 30,883 — 30,883 Industrial Products 26,623 26,623 Total $ 265,394 $ 113,483 $ 26,623 $ 405,500 Three Months Ended March 31, 2018 (in thousands) Electronics Segment Automotive Segment Industrial Segment Total Electronics – Passive Products and Sensors $ 114,495 $ — $ — $ 114,495 Electronics – Semiconductor 149,916 — — 149,916 Passenger Car Products — 63,580 — 63,580 Automotive Sensors — 31,323 — 31,323 Commercial Vehicle Products — 31,228 — 31,228 Industrial Products — 27,271 27,271 Total $ 264,411 $ 126,131 $ 27,271 $ 417,813 See Note 16, Segment Information for net sales by segment and countries. Revenue Recognition The Company recognizes revenue on product sales in the period in which the Company satisfies its performance obligation and control of the product is transferred to the customer. The Company’s sales arrangements with customers are predominately short term in nature and generally provide for transfer of control at the time of shipment as this is the point at which title and risk of loss of the product transfers to the customer. At the end of each period, for those shipments where title to the products and the risk of loss and rewards of ownership do not transfer until the product has been received by the customer, the Company adjusts revenues and cost of sales for the delay between the time that the products are shipped and when they are received by the customer. The amount of revenue recorded reflects the consideration to which the Company expects to be entitled in exchange for goods and may include adjustments for customer allowance, rebates and price adjustments. The Company’s distribution channels are primarily through direct sales and independent third-party distributors. The Company elected the practical expedient under Accounting Standards Codification ("ASC") 340-40-25-4 to expense commissions when incurred as the amortization period of the commission asset the Company would have otherwise recognized is less than one year. Revenue and Billing The Company generally accepts orders from customers through receipt of purchase orders or electronic data interchange based on written sales agreements and purchasing contracts. Contract pricing and selling agreement terms are based on market factors, costs, and competition. Pricing is often negotiated as an adjustment (premium or discount) from the Company’s published price lists. The customer is invoiced when the Company’s products are shipped to them in accordance with the terms of the sales agreement. As the Company’s standard payment terms are less than one year, the Company elected the practical expedient under ASC 606-10-32-18 to not assess whether a contract has a significant financing component. The Company also elected the practical expedient provided in ASC 606-10-25-18B to treat all product shipping and handling activities as fulfillment activities, and therefore recognize the gross revenue associated with the contract, inclusive of any shipping and handling revenue. This is similar to the Company’s prior practice and therefore the effect of the new guidance is immaterial. Ship and Debit Program Some of the terms of the Company’s sales agreements and normal business conditions provide customers (distributors) the ability to receive price adjustments on products previously shipped and invoiced. This practice is common in the industry and is referred to as a “ship and debit” program. This program allows the distributor to debit the Company for the difference between the distributors’ contracted price and a lower price for specific transactions. Under certain circumstances (usually in a competitive situation or large volume opportunity), a distributor will request authorization for pricing allowances to reduce its price. When the Company approves such a reduction, the distributor is authorized to “debit” its account for the difference between the contracted price and the lower approved price. The Company establishes reserves for this program based on historic activity and actual authorizations for the debit and recognizes these debits as a reduction of revenue. Return to Stock The Company has a return to stock policy whereby certain customers, with prior authorization from Littelfuse management, can return previously purchased goods for full or partial credit. The Company establishes an estimated allowance for these returns based on historic activity. Sales revenue and cost of sales are reduced to anticipate estimated returns. Volume Rebates The Company offers volume based sales incentives to certain customers to encourage greater product sales. If customers achieve their specific quarterly or annual sales targets, they are entitled to rebates. The Company estimates the projected amount of rebates that will be achieved by the customer and recognizes this estimated cost as a reduction to revenue as products are sold.
Recently Adopted and Issued Accounting Standards	Recently Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, "Leases" (Topic 842), ("ASC 842"). This ASU requires lessees to recognize, on the balance sheet, assets and liabilities for the rights and obligations created by leases of greater than twelve months. The accounting by lessors will remain largely unchanged. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. Adoption requires using a modified retrospective transition with either 1) periods prior to the adoption date being recast or 2) a cumulative-effect adjustment recognized to the opening balance of retained earnings on the adoption date with prior periods not recast. The Company adopted the standard on December 30, 2018 using alternative modified retrospective transition method provided in ASU No. 2018-11, "Leases (Topic 842): Target Improvements." Under this method, the Company recorded a cumulative-effect adjustment as of December 30, 2018 and did not record any retrospective adjustments to comparative periods to reflect the adoption of ASC 842. The new standard provides a number of optional practical expedients in transition. The Company has elected the ‘package of practical expedients’ which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs. The Company has not elected the use-of-hindsight. Adoption of ASC 842 resulted in the recognition of operating lease right-of-use assets ("ROU") net of deferred rent of $26.1 million and lease liabilities of $29.4 million , as of December 30, 2018 for operating leases on its Condensed Consolidated Balance Sheets, with no impact to its Condensed Consolidated Statements of Net Income and no impact on Condensed Consolidated Statements of Cash Flow.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and Other Information (Tables)	3 Months Ended
	Mar. 30, 2019
Accounting Policies [Abstract]
Revenue Disaggregation	The following tables disaggregate the Company’s revenue by primary business units for the three months ended March 30, 2019 and March 31, 2018 : Three Months Ended March 30, 2019 (in thousands) Electronics Segment Automotive Segment Industrial Segment Total Electronics – Passive Products and Sensors $ 108,377 $ — $ — $ 108,377 Electronics – Semiconductor 157,017 — — 157,017 Passenger Car Products — 56,543 — 56,543 Automotive Sensors — 26,057 — 26,057 Commercial Vehicle Products — 30,883 — 30,883 Industrial Products 26,623 26,623 Total $ 265,394 $ 113,483 $ 26,623 $ 405,500 Three Months Ended March 31, 2018 (in thousands) Electronics Segment Automotive Segment Industrial Segment Total Electronics – Passive Products and Sensors $ 114,495 $ — $ — $ 114,495 Electronics – Semiconductor 149,916 — — 149,916 Passenger Car Products — 63,580 — 63,580 Automotive Sensors — 31,323 — 31,323 Commercial Vehicle Products — 31,228 — 31,228 Industrial Products — 27,271 27,271 Total $ 264,411 $ 126,131 $ 27,271 $ 417,813

Acquisitions (Tables)

Acquisitions (Tables)	3 Months Ended
	Mar. 30, 2019
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the purchase price allocation of the fair value of assets acquired and liabilities assumed in the IXYS acquisition: (in thousands) Purchase Price Allocation Total purchase consideration: Cash, net of cash acquired $ 302,865 Cash settled stock options 3,622 Littelfuse stock 434,192 Converted stock options 38,109 Total purchase consideration $ 778,788 Allocation of consideration to assets acquired and liabilities assumed: Current assets, net $ 155,930 Property, plant, and equipment 77,442 Intangible assets 212,720 Goodwill 382,360 Other non-current assets 28,706 Other non-current liabilities (78,370 ) $ 778,788
Business Acquisition, Pro Forma Information	The pro forma amounts presented are not necessarily indicative of either the actual consolidated results had the IXYS acquisition occurred as of January 1, 2017 or of future consolidated operating results. Three Months Ended (in thousands, except per share amounts) March 31, 2018 Net sales $ 434,526 Income before income taxes 81,924 Net income 63,933 Net income per share — basic 2.57 Net income per share — diluted 2.53
Business Acquisition, Pro Forma Information, Nonrecurring Adjustments	Pro forma results presented above primarily reflect the following adjustments: Three Months Ended (in thousands) March 31, 2018 Amortization (a) $ 1,902 Transaction costs (b) 9,976 Amortization of inventory step-up (c) 17,896 Stock compensation (d) 4,479 Income tax impact of above items (7,701 ) (a) The amortization adjustment for the three months ended March 31, 2018 primarily reflects the reduction of amortization expense in the period related to the Order backlog intangible asset. The Order backlog has a useful life of twelve months and was fully amortized in the fiscal 2017 pro forma results. (b) The transaction cost adjustments reflect the reversal of certain bank and attorney fees from the three months ended March 31, 2018 and recognition of those fees during the three months ended April 1, 2017. (c) The amortization of inventory step-up adjustment reflects the reversal of the amount recognized during the three months ended March 31, 2018 and recognition of those fees during the three months ended April 1, 2017. The inventory step-up was amortized over five months as the inventory was sold. (d) The stock compensation adjustment reflects the reversal of the portion of stock compensation for IXYS stock options that were converted to Littelfuse stock options and expensed immediately during the three months ended March 31, 2018 .

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 30, 2019
Inventory Disclosure [Abstract]
Schedule of Inventory	The components of inventories at March 30, 2019 and December 29, 2018 are as follows: (in thousands) March 30 December 29 Raw materials $ 75,949 $ 69,883 Work in process 90,538 88,505 Finished goods 95,172 99,840 Total $ 261,659 $ 258,228

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	3 Months Ended
	Mar. 30, 2019
Property, Plant and Equipment [Abstract]
Components of net property, plant, and equipment	The components of net property, plant, and equipment at March 30, 2019 and December 29, 2018 are as follows: (in thousands) March 30 December 29 Land $ 25,607 $ 25,630 Building 114,506 114,636 Equipment 599,254 583,043 Accumulated depreciation and amortization (397,033 ) (383,415 ) Total $ 342,334 $ 339,894

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The amounts for goodwill and changes in the carrying value by segment for the three months ended March 30, 2019 are as follows: (in thousands) Electronics Automotive Industrial Total As of December 29, 2018 $ 656,039 $ 132,332 $ 38,344 $ 826,715 Currency translation (1,400 ) 102 50 (1,248 ) As of March 30, 2019 $ 654,639 $ 132,434 $ 38,394 $ 825,467
Schedule of Finite-Lived Intangible Assets	The components of other intangible assets at March 30, 2019 are as follows: (in thousands, except weighted average useful life) Weighted Average Useful Life (Years) Gross Carrying Value Accumulated Amortization Net Book Value Patents, licenses and software 11.1 $ 138,951 $ 72,219 $ 66,732 Distribution network 12.3 43,797 35,049 8,748 Customer relationships, trademarks, and tradenames 17.2 374,204 99,263 274,941 Total $ 556,952 $ 206,531 $ 350,421
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated annual amortization expense related to intangible assets with definite lives as of March 30, 2019 is as follows: (in thousands) Amount 2019 $ 49,524 2020 38,776 2021 36,930 2022 35,884 2023 30,423 2024 and thereafter 169,075 Total $ 360,612

Lease Commitments (Tables)

Lease Commitments (Tables)	3 Months Ended
	Mar. 30, 2019
Leases [Abstract]
Supplemental balance sheet information related to leases	The following table presents the classification of ROU assets and lease liabilities as of March 30, 2019 : Leases (in thousands) Condensed Consolidated Balance Sheet Classification March 30, 2019 Assets Operating ROU assets Right of use lease assets, net $ 24,725 Liabilities Current operating lease liabilities Accrued liabilities $ 7,447 Non-current operating lease liabilities Non-current operating lease liabilities 19,950 Total lease liabilities $ 27,397
Components of lease expense and supplemental cash flow information	Other Information (in thousands) Three Months Ended Cash paid for amounts included in the measurement of lease liabilities Operating cash flow payments for operating leases $ (2,253 ) Leased assets obtained in exchange for operating lease liabilities 859 The following table represents the lease costs for the three months ended March 30, 2019 : Leases cost (in thousands) Condensed Consolidated Statements of Net Income Classification March 30, 2019 Short-term lease expenses Cost of sales, SG&A expenses $ 153 Variable lease expenses Cost of sales, SG&A expenses 194 Operating lease rent expenses Cost of sales, SG&A expenses 2,193 Total operating lease costs Cost of sales, SG&A expenses $ 2,540
Maturities of lease liabilities	Maturity of Lease Liabilities as of March 30, 2019 (in thousands) Operating leases 2019 (excluding the three months ended March 30, 2019) $ 6,574 2020 7,551 2021 5,779 2022 4,665 2023 3,062 2024 and thereafter 3,064 Total lease payments $ 30,695 Present value of lease Liabilities $ 27,397
Operating lease term and discount rate	Operating Lease Term and Discount Rate March 30, 2019 Weighted-average remaining lease term (years) 4.40 Weighted-average discount rate 5.17 %

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	3 Months Ended
	Mar. 30, 2019
Payables and Accruals [Abstract]
Components of accrued liabilities	The components of accrued liabilities at March 30, 2019 and December 29, 2018 are as follows: (in thousands) March 30, 2019 December 29, 2018 Employee-related liabilities $ 38,479 $ 60,640 Other non-income taxes 25,379 21,523 Operating lease liability 7,447 — Professional services 5,395 6,169 Interest 2,487 5,137 Accrued share repurchases — 4,349 Restructuring liability 2,144 3,887 Other 25,883 36,700 Total $ 107,214 $ 138,405

Restructuring, Impairment and_2

Restructuring, Impairment and Other Charges (Tables)	3 Months Ended
	Mar. 30, 2019
Restructuring and Related Activities [Abstract]
Restructuring, impairment and other charges	The Company recorded restructuring, impairment and other charges-net for three months ended March 30, 2019 and March 31, 2018 as follows: Three months ended March 30, 2019 (in thousands) Electronics Automotive Industrial Total Employee terminations $ 1,800 $ 605 $ 47 $ 2,452 Other restructuring charges 13 20 250 283 Total restructuring charges $ 1,813 $ 625 $ 297 $ 2,735 Three months ended March 31, 2018 (in thousands) Electronics Automotive Industrial Total Employee terminations $ 677 $ 99 $ 3 $ 779 Total restructuring charges $ 677 $ 99 $ 3 $ 779

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 30, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The carrying amounts of debt at March 30, 2019 and December 29, 2018 are as follows: (in thousands) March 30, December 29, Term Loan $ 150,000 $ 155,000 Euro Senior Notes, Series A due 2023 131,499 133,417 Euro Senior Notes, Series B due 2028 106,772 108,330 U.S. Senior Notes, Series A due 2022 25,000 25,000 U.S. Senior Notes, Series B due 2027 100,000 100,000 U.S. Senior Notes, Series A due 2025 50,000 50,000 U.S. Senior Notes, Series B due 2030 125,000 125,000 Other 2,619 2,619 Unamortized debt issuance costs (4,380 ) (4,636 ) Total debt 686,510 694,730 Less: Current maturities (10,000 ) (10,000 ) Total long-term debt $ 676,510 $ 684,730

Fair Value of Assets and Liab_2

Fair Value of Assets and Liabilities (Tables)	3 Months Ended
	Mar. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The following table presents assets measured at fair value by classification within the fair value hierarchy as of December 29, 2018 : Fair Value Measurements Using (in thousands) Quoted Prices in Significant Significant Total Investments in equity securities $ 10,312 $ — $ — $ 10,312 Mutual funds 9,112 — — 9,112 The following table presents assets measured at fair value by classification within the fair value hierarchy as of March 30, 2019 : Fair Value Measurements Using (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Investments in equity securities $ 10,551 $ — $ — $ 10,551 Mutual funds 9,806 — — 9,806
Fair Value, by Balance Sheet Grouping	The carrying value and estimated fair values of the Company’s Euro Senior Notes, Series A and Series B and USD Senior Notes, Series A and Series B, as of March 30, 2019 and December 29, 2018 were as follows: March 30, 2019 December 29, 2018 (in thousands) Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Euro Senior Notes, Series A due 2023 $ 131,499 $ 129,800 $ 133,417 $ 130,888 Euro Senior Notes, Series B due 2028 106,772 105,700 108,330 103,774 USD Senior Notes, Series A due 2022 25,000 24,374 25,000 24,115 USD Senior Notes, Series B due 2027 100,000 96,673 100,000 94,458 USD Senior Notes, Series A due 2025 50,000 48,349 50,000 47,434 USD Senior Notes, Series B due 2030 125,000 118,090 125,000 114,731

Benefit Plans (Tables)

Benefit Plans (Tables)	3 Months Ended
	Mar. 30, 2019
Retirement Benefits [Abstract]
Schedule of Net Benefit Costs	The components of net periodic benefit cost for the three months ended March 30, 2019 and March 31, 2018 were as follows: For the Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Components of net periodic benefit cost: Service cost $ 500 $ 533 Interest cost 784 501 Expected return on plan assets (790 ) (540 ) Amortization of prior service 62 74 Net periodic benefit cost $ 556 $ 568

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 30, 2019
Equity [Abstract]
Schedule of Components of Comprehensive Income (Loss)	Change in other comprehensive (loss) income by component were as follows: (in thousands) Three Months Ended March 30, 2019 Three Months Ended March 31, 2018 Pre-tax Tax Net of Tax Pre-tax Tax Net of Tax Defined benefit pension plan adjustments $ (78 ) $ (29 ) $ (49 ) $ (68 ) $ (65 ) $ (3 ) Foreign currency translation adjustments 8,122 — 8,122 (276 ) — (276 ) Total change in other comprehensive income (loss) $ 8,044 $ (29 ) $ 8,073 $ (344 ) $ (65 ) $ (279 )
Schedule of Accumulated Other Comprehensive Income (Loss)	The following tables set forth the changes in accumulated other comprehensive (loss) income by component for the three months ended March 30, 2019 and March 31, 2018 : (in thousands) Pension and postretirement liability and reclassification adjustments Foreign currency translation adjustment Accumulated other comprehensive income (loss) Balance at December 29, 2018 $ (9,959 ) $ (87,965 ) $ (97,924 ) Activity in the period (49 ) 8,122 8,073 Balance at March 30, 2019 $ (10,008 ) $ (79,843 ) $ (89,851 ) (in thousands) Pension and postretirement liability and reclassification adjustments Unrealized gain (loss) on investments Foreign currency translation adjustment Accumulated other comprehensive income (loss) Balance at December 30, 2017 $ (10,836 ) $ 9,795 $ (62,627 ) $ (63,668 ) Cumulative effect adjustment (a) — (9,795 ) — (9,795 ) Activity in the period (3 ) — (276 ) (279 ) Balance at March 31, 2018 $ (10,839 ) $ — $ (62,903 ) $ (73,742 ) (a)The Company adopted ASU 2016-01 on December 31, 2017 on a modified retrospective basis, recognizing the cumulative effect as a $9.8 million increase to retained earnings.
Reclassification out of Accumulated Other Comprehensive Income	Amounts reclassified from accumulated other comprehensive (loss) income to earnings for the three months ended March 30, 2019 and March 31, 2018 were as follows: Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Pension and Postemployment plans: Amortization of prior service $ 62 $ 74

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 30, 2019
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of basic and diluted earnings per share: Three Months Ended (in thousands, except per share amounts) March 30, 2019 March 31, 2018 Numerator: Net income as reported $ 36,989 $ 36,029 Denominator: Weighted average shares outstanding Basic 24,717 24,339 Effect of dilutive securities 292 436 Diluted 25,009 24,775 Earnings Per Share: Basic earnings per share $ 1.50 $ 1.48 Diluted earnings per share $ 1.48 $ 1.45

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 30, 2019
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Segment information is summarized as follows: Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Net sales Electronics $ 265,394 $ 264,411 Automotive 113,483 126,131 Industrial 26,623 27,271 Total net sales $ 405,500 $ 417,813 Depreciation and amortization Electronics $ 15,342 $ 13,678 Automotive 6,877 5,970 Industrial 1,060 1,460 Other — 2,504 Total depreciation and amortization $ 23,279 $ 23,612 Operating income (loss) Electronics $ 49,037 $ 53,964 Automotive 13,200 18,390 Industrial 3,505 4,709 Other (a) (5,069 ) (39,492 ) Total operating income 60,673 37,571 Interest expense 5,686 5,423 Foreign exchange loss (gain) 4,243 (10,555 ) Other expense (income), net 4,305 (1,943 ) Income before income taxes $ 46,439 $ 44,646 (a) Included in “Other” Operating income (loss) for the 2019 first quarter is $2.4 million of acquisition integration charges primarily related to the IXYS acquisition. In addition, there were $2.7 million of restructuring charges primarily related to employee termination costs. The first quarter of 2018 includes approximately $38.6 million of charges primarily related to the IXYS acquisition, which include $17.9 million of purchase accounting inventory step-up charges, $11.6 million in acquisition-related and integration costs primarily related to legal, accounting and other expenses, $2.5 million in backlog amortization costs, and $4.5 million in stock compensation expense recognized immediately upon close for converted IXYS options related to prior service periods and $2.1 million change in control expense related to IXYS. In addition, there were $0.8 million of employee termination costs and $0.1 million of acquisition-related expenses for other contemplated acquisitions.
Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country	The Company’s net sales by country were as follows: Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Net sales United States $ 119,528 $ 123,877 China 57,334 106,508 Other countries (a) 228,638 187,428 Total net sales $ 405,500 $ 417,813 The Company’s long-lived assets by country were as follows: (in thousands) March 30, December 29, Long-lived assets United States $ 57,527 $ 58,691 China 94,807 95,806 Mexico 73,694 70,495 Germany 35,536 36,548 Philippines 36,223 32,459 Other countries (a) 44,547 45,895 Total long-lived assets $ 342,334 $ 339,894 The Company’s additions to long-lived assets by country were as follows: Three Months Ended (in thousands) March 30, 2019 March 31, 2018 Additions to long-lived assets United States $ 905 $ 2,909 China 1,225 5,144 Mexico 5,484 3,310 Germany 598 3,038 Philippines 5,229 2,162 Other countries (a) 635 1,346 Total additions to long-lived assets $ 14,076 $ 17,909 (a) Each country included in other countries are less than 10% of net sales.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies and Other Information (Details Textual) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 30, 2018
Accounting Policies [Abstract]
Right of use lease assets, net	$ 24,725	$ 26,100
Non-current operating lease liabilities	$ 19,950	$ 29,400

Summary of Significant Accoun_5

Summary of Significant Accounting Policies and Other Information - Revenue Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 405,500	$ 417,813
Electronics – Passive Products and Sensors
Disaggregation of Revenue [Line Items]
Net sales	108,377	114,495
Electronics – Semiconductor
Disaggregation of Revenue [Line Items]
Net sales	157,017	149,916
Passenger Car Products
Disaggregation of Revenue [Line Items]
Net sales	56,543	63,580
Automotive Sensors
Disaggregation of Revenue [Line Items]
Net sales	26,057	31,323
Commercial Vehicle Products
Disaggregation of Revenue [Line Items]
Net sales	30,883	31,228
Industrial Products
Disaggregation of Revenue [Line Items]
Net sales	26,623	27,271
Electronics Segment
Disaggregation of Revenue [Line Items]
Net sales	265,394	264,411
Electronics Segment | Electronics – Passive Products and Sensors
Disaggregation of Revenue [Line Items]
Net sales	108,377	114,495
Electronics Segment | Electronics – Semiconductor
Disaggregation of Revenue [Line Items]
Net sales	157,017	149,916
Electronics Segment | Passenger Car Products
Disaggregation of Revenue [Line Items]
Net sales	0	0
Electronics Segment | Automotive Sensors
Disaggregation of Revenue [Line Items]
Net sales	0	0
Electronics Segment | Commercial Vehicle Products
Disaggregation of Revenue [Line Items]
Net sales	0	0
Electronics Segment | Industrial Products
Disaggregation of Revenue [Line Items]
Net sales		0
Automotive Segment
Disaggregation of Revenue [Line Items]
Net sales	113,483	126,131
Automotive Segment | Electronics – Passive Products and Sensors
Disaggregation of Revenue [Line Items]
Net sales	0	0
Automotive Segment | Electronics – Semiconductor
Disaggregation of Revenue [Line Items]
Net sales	0	0
Automotive Segment | Passenger Car Products
Disaggregation of Revenue [Line Items]
Net sales	56,543	63,580
Automotive Segment | Automotive Sensors
Disaggregation of Revenue [Line Items]
Net sales	26,057	31,323
Automotive Segment | Commercial Vehicle Products
Disaggregation of Revenue [Line Items]
Net sales	30,883	31,228
Automotive Segment | Industrial Products
Disaggregation of Revenue [Line Items]
Net sales
Industrial Segment
Disaggregation of Revenue [Line Items]
Net sales	26,623	27,271
Industrial Segment | Electronics – Passive Products and Sensors
Disaggregation of Revenue [Line Items]
Net sales	0	0
Industrial Segment | Electronics – Semiconductor
Disaggregation of Revenue [Line Items]
Net sales	0	0
Industrial Segment | Passenger Car Products
Disaggregation of Revenue [Line Items]
Net sales	0	0
Industrial Segment | Automotive Sensors
Disaggregation of Revenue [Line Items]
Net sales	0	0
Industrial Segment | Commercial Vehicle Products
Disaggregation of Revenue [Line Items]
Net sales	0	0
Industrial Segment | Industrial Products
Disaggregation of Revenue [Line Items]
Net sales	$ 26,623	$ 27,271

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) $ / shares in Units, $ in Thousands	Jan. 17, 2018USD ($)customer$ / shares	Mar. 30, 2019USD ($)$ / shares	Mar. 31, 2018USD ($)	Dec. 29, 2018USD ($)$ / shares
Business Acquisition [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.01		$ 0.01
Non-cash inventory charges		$ 0	$ 17,896
Cash, net of cash acquired		775	306,487
Non-cash, fair value of commitment to purchase non-controlling interest		$ 0	9,000
Inventory amortization period		5 months
IXYS Corporation
Business Acquisition [Line Items]
Number of customers | customer	3,500
Common stock, par value (in dollars per share) | $ / shares	$ 0.01
Share price (in dollars per share) | $ / shares	$ 23
Share exchange ratio	0.1265
Share price (in dollars per share) | $ / shares	$ 207.5
Consideration excluding value of stock options converted	$ 814,800
Cash	380,600
Littelfuse stock	434,192
Value of options converted	41,700
Consideration transferred	856,500
Receivables	49,100
Acquisition related costs				$ 10,200
Cash, net of cash acquired	$ 302,865
Other | Operating Income (Loss)
Business Acquisition [Line Items]
Allocated share based compensation			4,500
Acquisition related costs			38,600
Inventory adjustment			17,900
Employee Stock Option | IXYS Corporation
Business Acquisition [Line Items]
Allocated share based compensation			5,900
Employee Stock Option | IXYS Corporation | Selling, General and Administrative Expenses
Business Acquisition [Line Items]
Allocated share based compensation			$ 4,500

Acquisitions - Preliminary Pric

Acquisitions - Preliminary Price Allocation (Details) - USD ($) $ in Thousands	Jan. 17, 2018	Mar. 30, 2019	Mar. 31, 2018	Dec. 29, 2018
Total purchase consideration:
Cash, net of cash acquired		$ 775	$ 306,487
Non-cash, fair value of commitment to purchase non-controlling interest		0	$ 9,000
Allocation of consideration to assets acquired and liabilities assumed:
Goodwill		$ 825,467		$ 826,715
IXYS Corporation
Total purchase consideration:
Cash	$ 380,600
Cash, net of cash acquired	302,865
Cash settled stock options	3,622
Littelfuse stock	434,192
Converted stock options	38,109
Total purchase consideration	778,788
Allocation of consideration to assets acquired and liabilities assumed:
Current assets, net	155,930
Property, plant, and equipment	77,442
Intangible assets	212,720
Goodwill	382,360
Other non-current assets	28,706
Other non-current liabilities	(78,370)
Assets acquired and liabilities assumed	$ 778,788

Acquisitions - Business Acquisi

Acquisitions - Business Acquisition Pro Forma Information (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)$ / shares
Business Combinations [Abstract]
Net sales	$ 434,526
Income before income taxes	81,924
Net income	$ 63,933
Net income per share — basic (in dollars per share) | $ / shares	$ 2.57
Net income per share — diluted (in dollars per share) | $ / shares	$ 2.53

Acquisitions - Pro Forma Inform

Acquisitions - Pro Forma Information Adjustments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income	$ 63,933
Amortization
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income	1,902
Transaction costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income	9,976
Amortization of inventory step-up
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income	17,896
Stock compensation
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income	4,479
Income tax impact of above items
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income	$ (7,701)

Inventories - Components of Inv

Inventories - Components of Inventories (Details) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 75,949	$ 69,883
Work in process	90,538	88,505
Finished goods	95,172	99,840
Total	$ 261,659	$ 258,228

Property, Plant, and Equipmen_2

Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Dec. 29, 2018
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (397,033)		$ (383,415)
Net property, plant, and equipment	342,334		339,894
Depreciation	13,088	$ 11,614
Land
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	25,607		25,630
Building
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	114,506		114,636
Equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 599,254		$ 583,043

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Amounts for Goodwill and Changes in Carrying Value by Operating Segment (Details) $ in Thousands	3 Months Ended
	Mar. 30, 2019USD ($)
Goodwill [Roll Forward]
Balance	$ 826,715
Currency translation	(1,248)
Balance	825,467
Electronics
Goodwill [Roll Forward]
Balance	656,039
Currency translation	(1,400)
Balance	654,639
Automotive
Goodwill [Roll Forward]
Balance	132,332
Currency translation	102
Balance	132,434
Industrial
Goodwill [Roll Forward]
Balance	38,344
Currency translation	50
Balance	$ 38,394

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangibles	$ 10,191	$ 11,998

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Details of Other Intangible Assets and Related Future Amortization Expense (Details) $ in Thousands	3 Months Ended
	Mar. 30, 2019USD ($)
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 556,952
Accumulated Amortization	206,531
Net Book Value	$ 350,421
Patents, licenses and software
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life (Years)	11 years 1 month 6 days
Gross Carrying Value	$ 138,951
Accumulated Amortization	72,219
Net Book Value	$ 66,732
Distribution network
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life (Years)	12 years 3 months 18 days
Gross Carrying Value	$ 43,797
Accumulated Amortization	35,049
Net Book Value	$ 8,748
Customer relationships, trademarks, and tradenames
Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life (Years)	17 years 2 months 12 days
Gross Carrying Value	$ 374,204
Accumulated Amortization	99,263
Net Book Value	$ 274,941

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Estimated Amortization Expense Related to Intangible Assets with Definite Lives (Details) $ in Thousands	Mar. 30, 2019USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2019	$ 49,524
2020	38,776
2021	36,930
2022	35,884
2023	30,423
2024 and thereafter	169,075
Total	$ 360,612

Lease Commitments - Balance She

Lease Commitments - Balance Sheet, Operating Lease Term and Discount Rate (Details) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 30, 2018	Dec. 29, 2018
Leases [Abstract]
Operating ROU assets	$ 24,725	$ 26,100
Current operating lease liabilities	7,447		$ 0
Non-current operating lease liabilities	19,950	$ 29,400
Total lease liabilities	$ 27,397
Weighted-average remaining lease term (years)	4 years 4 months 24 days
Weighted-average discount rate	5.17%

Lease Commitments - Lease Cost

Lease Commitments - Lease Cost (Details) $ in Thousands	3 Months Ended
	Mar. 30, 2019USD ($)
Leases [Abstract]
Short-term lease expenses	$ 153
Variable lease expenses	194
Operating lease rent expenses	2,193
Total operating lease costs	$ 2,540

Lease Commitments - Maturities

Lease Commitments - Maturities of Lease Liabilities (Details) $ in Thousands	Mar. 30, 2019USD ($)
Operating Leases
2019 (excluding the three months ended March 30, 2019)	$ 6,574
2020	7,551
2021	5,779
2022	4,665
2023	3,062
2024 and thereafter	3,064
Total lease payments	30,695
Present value of lease Liabilities	$ 27,397

Lease Commitments - Supplementa

Lease Commitments - Supplemental Cash Flow Information (Details) $ in Thousands	3 Months Ended
	Mar. 30, 2019USD ($)
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flow payments for operating leases	$ (2,253)
Leased assets obtained in exchange for operating lease liabilities	$ 859

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018
Payables and Accruals [Abstract]
Employee-related liabilities	$ 38,479	$ 60,640
Other non-income taxes	25,379	21,523
Operating lease liability	7,447	0
Professional services	5,395	6,169
Interest	2,487	5,137
Accrued share repurchases	0	4,349
Restructuring liability	2,144	3,887
Other	25,883	36,700
Total	$ 107,214	$ 138,405

Restructuring, Impairment and_3

Restructuring, Impairment and Other Charges (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Apr. 30, 2019	Dec. 29, 2018
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 2,735	$ 779
Restructuring costs		800
Restructuring reserves	2,100			$ 3,900
Employee terminations
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	2,452	779
Other restructuring charges
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	283
Facility closing | Minimum | Subsequent Event
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost			$ 5,000
Facility closing | Maximum | Subsequent Event
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost			$ 7,000
Electronics
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	1,813	677
Electronics | Employee terminations
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	1,800	677
Electronics | Other restructuring charges
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	13
Automotive
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	625	99
Automotive | Employee terminations
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	605	99
Automotive | Other restructuring charges
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	20
Industrial
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	297	3
Industrial | Employee terminations
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	47	$ 3
Industrial | Other restructuring charges
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 250

Debt - Carrying Amounts of Long

Debt - Carrying Amounts of Long-term Debt (Details) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (4,380)	$ (4,636)
Total debt	686,510	694,730
Less: Current maturities	(10,000)	(10,000)
Total long-term debt	676,510	684,730
Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	150,000	155,000
Euro Senior Notes, Series A due 2023
Debt Instrument [Line Items]
Long-term debt, gross	131,499	133,417
Euro Senior Notes, Series B due 2028
Debt Instrument [Line Items]
Long-term debt, gross	106,772	108,330
U.S. Senior Notes, Series A due 2022
Debt Instrument [Line Items]
Long-term debt, gross	25,000	25,000
U.S. Senior Notes, Series B due 2027
Debt Instrument [Line Items]
Long-term debt, gross	100,000	100,000
U.S. Senior Notes, Series A due 2025
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
U.S. Senior Notes, Series B due 2030
Debt Instrument [Line Items]
Long-term debt, gross	125,000	125,000
Other
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,619	$ 2,619

Debt - Narrative (Details)

Debt - Narrative (Details)	Jan. 16, 2018USD ($)	Oct. 13, 2017USD ($)advance	Mar. 04, 2016USD ($)	Mar. 30, 2019USD ($)	Mar. 31, 2018USD ($)	Dec. 29, 2018	Nov. 15, 2017USD ($)series	Oct. 12, 2017USD ($)	Feb. 15, 2017USD ($)	Dec. 08, 2016EUR (€)series	Dec. 08, 2016USD ($)series
Debt Instrument [Line Items]
Interest paid				$ 8,000,000	$ 4,000,000
Credit Agreement
Debt Instrument [Line Items]
Debt term			5 years
Maximum borrowing capacity			$ 700,000,000
Additional uncommitted borrowing capacity		$ 300,000,000	150,000,000
Additional uncommitted borrowing capacity, minimum increments			$ 25,000,000
Number of advances | advance		2
Effective interest rate				3.75%
Letter of credit outstanding				$ 100,000
Credit Agreement | Minimum
Debt Instrument [Line Items]
Commitment fee			0.15%
Credit Agreement | Maximum
Debt Instrument [Line Items]
Commitment fee			0.25%
Credit Agreement | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Credit Agreement | LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate			2.00%
Credit Agreement | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			0.00%
Credit Agreement | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 700,000,000	$ 575,000,000					$ 575,000,000
Remaining borrowing capacity				699,900,000
Credit Agreement | Term Loan Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity, credit facility		200,000,000	$ 125,000,000
Proceeds from issuance of debt	$ 75,000,000	$ 125,000,000
Quarterly payments, percentage of loan						1.25%
Periodic payment	2,500,000
Repayments of debt				$ 5,000,000
Euro Senior Notes, Series A and B
Debt Instrument [Line Items]
Face amount of debt | €										€ 212,000,000
Number of series | series							2			2	2
Euro Senior Notes, Series A due 2023
Debt Instrument [Line Items]
Face amount of debt | €										€ 117,000,000
Stated interest rate										1.14%	1.14%
Euro Senior Notes, Series B due 2028
Debt Instrument [Line Items]
Face amount of debt | €										€ 95,000,000
Stated interest rate										1.83%	1.83%
U.S. Senior Notes, Series A and B
Debt Instrument [Line Items]
Face amount of debt											$ 125,000,000
U.S. Senior Notes, Series A
Debt Instrument [Line Items]
Face amount of debt									$ 25,000,000
Stated interest rate									3.03%
U.S. Senior Notes, Series B
Debt Instrument [Line Items]
Face amount of debt									$ 100,000,000
Stated interest rate									3.74%
US Senior Notes A and B Due 2025 and 2030
Debt Instrument [Line Items]
Face amount of debt							$ 175,000,000
U.S. Senior Notes, Series A due 2025
Debt Instrument [Line Items]
Face amount of debt	$ 50,000,000
Stated interest rate	3.48%
U.S. Senior Notes, Series B due 2030
Debt Instrument [Line Items]
Face amount of debt	$ 125,000,000
Stated interest rate	3.78%

Fair Value of Assets and Liab_3

Fair Value of Assets and Liabilities - Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Dec. 29, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities	$ 10,551	$ 10,312
Mutual funds	9,806	9,112
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities	10,551	10,312
Mutual funds	9,806	9,112
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities	0	0
Mutual funds	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities	0	0
Mutual funds	0	$ 0
Other Expense (Income)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges	2,800
Investments in equity securities	$ 1,200

Fair Value of Assets and Liab_4

Fair Value of Assets and Liabilities - Carrying Value and Estimated Fair Value of Senior Notes (Details) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018
Carrying Value | Euro Senior Notes, Series A due 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	$ 131,499	$ 133,417
Carrying Value | Euro Senior Notes, Series B due 2028
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	106,772	108,330
Carrying Value | U.S. Senior Notes, Series A due 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	25,000	25,000
Carrying Value | U.S. Senior Notes, Series B due 2027
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	100,000	100,000
Carrying Value | U.S. Senior Notes, Series A due 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	50,000	50,000
Carrying Value | U.S. Senior Notes, Series B due 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	125,000	125,000
Estimated Fair Value | Euro Senior Notes, Series A due 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	129,800	130,888
Estimated Fair Value | Euro Senior Notes, Series B due 2028
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	105,700	103,774
Estimated Fair Value | U.S. Senior Notes, Series A due 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	24,374	24,115
Estimated Fair Value | U.S. Senior Notes, Series B due 2027
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	96,673	94,458
Estimated Fair Value | U.S. Senior Notes, Series A due 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	48,349	47,434
Estimated Fair Value | U.S. Senior Notes, Series B due 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt fair value	$ 118,090	$ 114,731

Benefit Plans - Narrative (Deta

Benefit Plans - Narrative (Details) $ in Millions	Mar. 30, 2019USD ($)
Retirement Benefits [Abstract]
Contributions expected	$ 2.3

Benefit Plans - Benefit Plan Ex

Benefit Plans - Benefit Plan Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Retirement Benefits [Abstract]
Service cost	$ 500	$ 533
Interest cost	784	501
Expected return on plan assets	(790)	(540)
Amortization of prior service	62	74
Net periodic benefit cost	$ 556	$ 568

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) - Schedule of Components of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Other Comprehensive Income (Loss) [Line Items]
Pre-tax	$ 8,044	$ (344)
Tax	(29)	(65)
Total change in other comprehensive income (loss)	8,073	(279)
Pension and postretirement liability and reclassification adjustments
Other Comprehensive Income (Loss) [Line Items]
Pre-tax	(78)	(68)
Tax	(29)	(65)
Total change in other comprehensive income (loss)	(49)	(3)
Foreign currency translation adjustment
Other Comprehensive Income (Loss) [Line Items]
Pre-tax	8,122	(276)
Tax	0	0
Total change in other comprehensive income (loss)	$ 8,122	$ (276)

Other Comprehensive Income (L_4

Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	$ 1,478,342	$ 927,556
Activity in the period	8,073	(279)
Balance	1,505,388	1,441,974
Pension and postretirement liability and reclassification adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(9,959)	(10,836)
Cumulative effect adjustment		0
Activity in the period	(49)	(3)
Balance	(10,008)	(10,839)
Unrealized gain (loss) on investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance		9,795
Cumulative effect adjustment		(9,795)
Activity in the period		0
Balance		0
Foreign currency translation adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(87,965)	(62,627)
Cumulative effect adjustment		0
Activity in the period	8,122	(276)
Balance	(79,843)	(62,903)
Accumulated other comprehensive income (loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(97,924)	(63,668)
Cumulative effect adjustment		(9,795)
Activity in the period	8,073	(279)
Balance	$ (89,851)	$ (73,742)

Other Comprehensive Income (L_5

Other Comprehensive Income (Loss) - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service	$ 250,272	$ 268,190
Amortization of prior service | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service	$ 62	$ 74

Income Taxes (Details Textual)

Income Taxes (Details Textual)	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	20.30%	19.30%

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Repurchases of common stock	$ 13,555
Share Repurchase Program
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Repurchase authorized (in shares)	1,000,000	1,000,000
Shares repurchased (in shares)	79,916
Repurchases of common stock	$ 13,600
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	77,047	0

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Numerator:
Net income as reported	$ 36,989	$ 36,029
Weighted average shares outstanding
Basic (in shares)	24,717	24,339
Effect of dilutive securities (in shares)	292	436
Diluted (in shares)	25,009	24,775
Earnings Per Share:
Basic earnings per share (in dollars per share)	$ 1.50	$ 1.48
Diluted earnings per share (in dollars per share)	$ 1.48	$ 1.45

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	Mar. 25, 2019	Mar. 30, 2019	Mar. 31, 2018	Dec. 29, 2018
Powersem
Related Party Transaction [Line Items]
Revenue from related parties		$ 0.1
Purchase from related party		0.8	$ 1.1
Receivable from related parties		0.1		$ 0.1
Payables to related parties		0.1		0.2
EB Tech
Related Party Transaction [Line Items]
Payables to related parties		0.1
Amount of transaction		0.1
ATEC
Related Party Transaction [Line Items]
Payables to related parties		0.4		$ 0.5
Amount of transaction		$ 1.5	$ 2.4
MWT
Related Party Transaction [Line Items]
Loss on disposal	$ 2.6
Powersem
Related Party Transaction [Line Items]
Ownership percentage		45.00%
EB Tech
Related Party Transaction [Line Items]
Ownership percentage		20.00%
ATEC
Related Party Transaction [Line Items]
Ownership percentage		24.00%

Segment Information - Segment I

Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Net sales	$ 405,500	$ 417,813
Depreciation and amortization	23,279	23,612
Operating income (loss)	60,673	37,571
Interest expense	5,686	5,423
Foreign exchange loss (gain)	4,243	(10,555)
Other expense (income), net	4,305	(1,943)
Income before income taxes	46,439	44,646
Electronics
Segment Reporting Information [Line Items]
Net sales	265,394	264,411
Depreciation and amortization	15,342	13,678
Operating income (loss)	49,037	53,964
Automotive
Segment Reporting Information [Line Items]
Net sales	113,483	126,131
Depreciation and amortization	6,877	5,970
Operating income (loss)	13,200	18,390
Industrial
Segment Reporting Information [Line Items]
Net sales	26,623	27,271
Depreciation and amortization	1,060	1,460
Operating income (loss)	3,505	4,709
Other
Segment Reporting Information [Line Items]
Depreciation and amortization	0	2,504
Operating income (loss)	$ (5,069)	$ (39,492)

Segment Information - Narrative

Segment Information - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 30, 2019USD ($)segment	Mar. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	3
Restructuring charges	$ 2,735	$ 779
Net sales | Geographic Concentration Risk | Other countries(a)
Segment Reporting Information [Line Items]
Concentration risk (less than)	10.00%
Other | Operating Income (Loss)
Segment Reporting Information [Line Items]
Acquisition related costs		38,600
Inventory adjustment		17,900
Legal, accounting and other expenses	$ 2,400	11,600
Backlog amortization costs		2,500
Allocated share based compensation		4,500
Change in control expense		2,100
Restructuring charges	$ 2,700
Impairment charges		800
Other asset impairment charges		$ 100

Segment Information - Revenues

Segment Information - Revenues and Long-lived Assets by Geographical Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Dec. 29, 2018
Segment Reporting Information [Line Items]
Net sales	$ 405,500	$ 417,813
Long-lived assets	342,334		$ 339,894
Additions to long-lived assets	14,076	17,909
United States
Segment Reporting Information [Line Items]
Net sales	119,528	123,877
Long-lived assets	57,527		58,691
Additions to long-lived assets	905	2,909
China
Segment Reporting Information [Line Items]
Net sales	57,334	106,508
Long-lived assets	94,807		95,806
Additions to long-lived assets	1,225	5,144
Mexico
Segment Reporting Information [Line Items]
Long-lived assets	73,694		70,495
Additions to long-lived assets	5,484	3,310
Germany
Segment Reporting Information [Line Items]
Long-lived assets	35,536		36,548
Additions to long-lived assets	598	3,038
Philippines
Segment Reporting Information [Line Items]
Long-lived assets	36,223		32,459
Additions to long-lived assets	5,229	2,162
Other countries(a)
Segment Reporting Information [Line Items]
Net sales	228,638	187,428
Long-lived assets	44,547		$ 45,895
Additions to long-lived assets	$ 635	$ 1,346