iRobot (IRBT) 10-Q 4 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	IRBT
Entity Registrant Name	IROBOT CORP
Entity Central Index Key	1,159,167
Current Fiscal Year End Date	--12-29
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		27,804,771

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 30, 2017
Current assets:
Cash and cash equivalents	$ 144,501	$ 128,635
Short term investments	39,960	37,225
Accounts receivable, net	69,532	142,829
Inventory	112,111	106,932
Other current assets	24,584	19,105
Total current assets	390,688	434,726
Property and equipment, net	47,223	44,579
Deferred tax assets	32,690	31,531
Goodwill	123,218	121,440
Intangible assets, net	40,613	44,712
Other assets	15,005	14,534
Total assets	649,437	691,522
Current liabilities:
Accounts payable	69,119	116,316
Accrued expenses	56,107	73,647
Deferred revenue and customer advances	6,271	7,761
Total current liabilities	131,497	197,724
Deferred tax liabilities	8,349	9,539
Other long-term liabilities	12,963	13,932
Total long-term liabilities	21,312	23,471
Total liabilities	152,809	221,195
Commitments and contingencies (Note 11)
Preferred stock, 5,000 shares authorized and none outstanding	0	0
Common stock, $0.01 par value, 100,000 shares authorized; 28,073 and 27,945 shares issued and outstanding at March 31, 2018 and December 30, 2017, respectively	280	279
Additional paid-in capital	191,021	190,067
Retained earnings	299,430	277,989
Accumulated other comprehensive income	5,897	1,992
Total stockholders’ equity	496,628	470,327
Total liabilities and stockholders’ equity	$ 649,437	$ 691,522

Consolidated Balance Sheets (U3

Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 30, 2017
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares outstanding
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	28,073,120	27,945,144
Common stock, shares outstanding	28,073,120	27,945,144

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2018	Apr. 01, 2017
Revenue		$ 217,068	$ 168,467
Cost of product revenue		96,501	80,260
Amortization of intangible assets		4,782	864
Total cost of revenue (1)	[1]	101,283	81,124
Gross margin		115,785	87,343
Operating expenses:
Research and development (1)	[1]	32,945	25,508
Selling and marketing (1)	[1]	31,329	22,575
General and administrative (1)	[1]	25,833	17,622
Amortization of intangible assets		273	0
Total operating expenses		90,380	65,705
Operating income		25,405	21,638
Other income, net		519	3
Income before income taxes		25,924	21,641
Income tax expense		5,523	5,282
Net income		$ 20,401	$ 16,359
Net income per share:
Basic		$ 0.73	$ 0.60
Diluted		$ 0.71	$ 0.58
Number of weighted average common shares used in per share calculations
Basic		27,988	27,304
Diluted		28,923	28,295
Stock-based compensation		$ 5,946	$ 4,331
Cost of revenue
Number of weighted average common shares used in per share calculations
Stock-based compensation		341	226
Research and development
Number of weighted average common shares used in per share calculations
Stock-based compensation		1,689	1,099
Selling and marketing
Number of weighted average common shares used in per share calculations
Stock-based compensation		738	570
General and administrative
Number of weighted average common shares used in per share calculations
Stock-based compensation		$ 3,178	$ 2,436
[1]	(1)Stock-based compensation recorded in the three months ended March 31, 2018 and April 1, 2017 breaks down by expense classification as follows: Three Months Ended March 31, 2018 April 1, 2017Cost of revenue$341 $226Research and development1,689 1,099Selling and marketing738 570General and administrative3,178 2,436

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Net income	$ 20,401	$ 16,359
Other comprehensive income (loss):
Net foreign currency translation adjustments	5,338	(52)
Net unrealized losses on cash flow hedges, net of tax	(1,851)	0
Net losses on cash flow hedge reclassified into earnings, net of tax	590	0
Net unrealized gains (losses) on marketable securities, net of tax	(172)	35
Total comprehensive income	$ 24,306	$ 16,342

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Cash flows from operating activities:
Net income	$ 20,401	$ 16,359
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,747	3,486
Stock-based compensation	5,946	4,331
Deferred income taxes, net	(3,061)	17
Non-cash director deferred compensation	16	16
Deferred rent	1,077	0
Other	(390)	(166)
Changes in operating assets and liabilities — (use) source
Accounts receivable	(73,642)	(25,155)
Inventory	(4,223)	(6,546)
Other assets	(6,114)	(1,745)
Accounts payable	(46,461)	(5,026)
Accrued expenses	(19,693)	(8,612)
Deferred revenue and customer advances	(517)	(284)
Long term liabilities	(360)	(558)
Net cash provided by operating activities	29,790	26,759
Cash flows from investing activities:
Additions of property and equipment	(8,717)	(3,008)
Change in other assets	379	(504)
Purchases of investments	(6,438)	(3,498)
Sales and maturities of investments	3,500	3,500
Net cash used in investing activities	(11,276)	(3,510)
Cash flows from financing activities:
Income tax withholding payment associated with restricted stock vesting	(3,478)	(2,778)
Proceeds from stock option exercises	399	722
Net cash used in financing activities	(3,079)	(2,056)
Effect of exchange rate changes on cash and cash equivalents	431	12
Net increase in cash and cash equivalents	15,866	21,205
Cash and cash equivalents, at beginning of period	128,635	214,523
Cash and cash equivalents, at end of period	144,501	235,728
Supplemental disclosure of cash flow information:
Cash paid for income taxes	4,660	5,563
Additions of property and equipment included in accounts payable	$ 3,003	$ 2,461

Description of Business

Description of Business	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business iRobot Corporation ("iRobot" or the "Company") designs and builds robots that empower people to do more. The Company develops robotic technology and applies it to produce and market consumer robots. The Company’s revenue is primarily generated from product sales through distributor and retail sales channels, as well as its on-line stores.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements include those of iRobot and its subsidiaries, after elimination of all intercompany balances and transactions. iRobot has prepared the accompanying unaudited consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP). In addition, certain prior year amounts have been reclassified to conform to the current year presentation. In the opinion of management, all adjustments necessary to the unaudited interim consolidated financial statements have been made to state fairly the Company's financial position. Interim results are not necessarily indicative of results for the full fiscal year or any future periods. The information included in this Form 10-Q should be read in conjunction with the Company's audited consolidated financial statements and notes thereto included in its Annual Report on Form 10-K for the fiscal year ended December 30, 2017, filed with the SEC on February 16, 2018. Use of Estimates The preparation of these financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities, revenue and expenses. These estimates and judgments, include but are not limited to, revenue recognition, including performance obligations, variable consideration and other obligations such as product returns and incentives; valuation of goodwill and acquired intangible assets; accounting for business combinations; evaluating loss contingencies; accounting for stock-based compensation including performance-based assessments; and accounting for income taxes and related valuation allowances. The Company bases these estimates and judgments on historical experience, market participant fair value considerations, projected future cash flows and various other factors that the Company believes are reasonable under the circumstances. Actual results may differ from the Company’s estimates. Fiscal Year-End The Company operates and reports using a 52 -53 week fiscal year ending on the Saturday closest to December 31. Accordingly, the Company’s fiscal quarters end on the Saturday that falls closest to the last day of the third month of each quarter. Other Assets During the three months ended March 31, 2018, the Company adopted Accounting Standards Update No. 2016-01, "Recognition and Measurement of Financial Assets and Financial Liabilities," which revises the classification and measurement of financial instruments. Upon adoption of this standard, the Company now classifies its cost method investments as equity securities without readily determinable fair values and measures these investments at cost, less any impairment, adjusted for observable price changes. At March 31, 2018 , other assets consisted primarily of equity securities without readily determinable fair values and an equity method investment totaling $14.8 million . There was no adjustment recorded to the carrying value of our equity securities without readily determinable fair values as a result of the adoption of ASU 2016-01. At December 30, 2017 , other assets consisted primarily of cost method investments and an equity method investment totaling $14.2 million . Net Income Per Share Basic income per share is calculated using the Company's weighted-average outstanding common shares. Diluted income per share is calculated using the Company's weighted-average outstanding common shares including the dilutive effect of stock awards as determined under the treasury stock method. The following table presents the calculation of both basic and diluted net income per share: Three Months Ended (In thousands, except per share amounts) March 31, 2018 April 1, 2017 Net income $ 20,401 $ 16,359 Weighted-average common shares outstanding 27,988 27,304 Dilutive effect of employee stock options and restricted shares 935 991 Diluted weighted-average common shares outstanding 28,923 28,295 Basic income per share $ 0.73 $ 0.60 Diluted income per share $ 0.71 $ 0.58 Restricted stock units and stock options representing approximately 0.1 million and 0.0 million shares of common stock for the three-month periods ended March 31, 2018 and April 1, 2017 , respectively, were excluded from the computation of diluted earnings per share as their effect would have been antidilutive. Recently Adopted Accounting Standards In February 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2018-02, "Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," which provides an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate under the Tax Cuts and Jobs Act is recorded. This guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. During the first quarter of 2018, the Company early adopted this standard, which did not have a material impact on the Company's consolidated financial statements and related disclosures. In October 2016, FASB issued ASU No. 2016-16, "Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory." ASU 2016-16 clarifies the accounting for the current and deferred income taxes for an intra-entity transfer of an asset other than inventory. ASU 2016-16 is effective for fiscal years beginning after December 15, 2017. During the first quarter of 2018, the Company adopted this standard, which did not have a material impact on the Company's consolidated financial statements and related disclosures. In January 2016, the FASB issued ASU No. 2016-01, "Recognition and Measurement of Financial Assets and Financial Liabilities," as amended by ASU No. 2018-03 in February 2018, which revises various aspects of the recognition, measurement, presentation and disclosure of financial instruments. The standard requires that marketable equity investments be measured at fair value with changes to fair value recognized in net income. ASU 2016-01 also provides a new measurement alternative for non-marketable equity investments that do not have a readily determinable fair value. Under the measurement alternative, investments are measured at cost, less any impairment, adjusted for changes from observable transactions for identical or similar investments of the same issuer. The Company adopted this guidance on December 31, 2017 and elected to record its non-marketable equity investments using the alternative measurement method, which did not have a material impact on the Company's consolidated financial statements and related disclosures. In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers," ("ASC 606") which provides guidance for revenue recognition. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. On December 31, 2017, the Company adopted the guidance using the modified retrospective method applied to those contracts that were not completed as of the adoption date. Under the modified retrospective method, the Company recognized the cumulative effect of the adoption and recorded a net increase of $1.0 million to the beginning retained earnings as of December 31, 2017. See Note 3, "Revenue Recognition," for the required disclosures related to the impact of adopting this standard and a discussion of the Company's updated policies related to revenue recognition. Recently Issued Accounting Standards In August 2017, the FASB issued ASU No. 2017-12, "Derivatives and Hedging," that was created to better align accounting rules with a company’s risk management activities, better reflect the economic results of hedging in the financial statements, and simplify hedge accounting treatment. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. For cash flow hedges existing at the adoption date, the standard requires adoption on a modified retrospective basis with a cumulative-effect adjustment to the consolidated balance sheet as of the beginning of the year of adoption. The amendments to presentation guidance and disclosure requirements are required to be adopted prospectively. The Company is currently evaluating the impact of the standard on its consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-08, "Receivables – Nonrefundable Fees and Other Costs," which shortens the amortization period of certain callable debt securities held at a premium. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the standard on its consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, "Measurement of Credit Losses on Financial Instruments," which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses rather than incurred losses to estimate credit losses on certain types of financial instruments. This may result in the earlier recognition of allowances for losses. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the standard on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, "Leases." ASU 2016-02 requires lessees to recognize the assets and liabilities on their balance sheet for the rights and obligations created by most leases and continue to recognize expenses on their income statements over the lease term. It will also require disclosures designed to give financial statement users information on the amount, timing, and uncertainty of cash flows arising from leases. The guidance is effective for annual reporting periods beginning after December 15, 2018 and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the pending adoption of ASU 2016-02 on its consolidated financial statements, and currently expects that most of its operating lease commitments will be subject to the new standard and recognized as operating lease liabilities and right-of-use assets upon its adoption of ASU 2016-02, which will increase the total assets and total liabilities that the Company reports relative to such amounts prior to adoption. From time to time, new accounting pronouncements are issued by FASB that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that recently issued standards, which are not yet effective, will not have a material impact on the Company’s consolidated financial statements upon adoption.

Revenue Recognition (Notes)

Revenue Recognition (Notes)	3 Months Ended
	Mar. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition The Company primarily derives its revenue from product sales. The Company sells products directly to consumers through on-line stores and indirectly through resellers and distributors. Revenue is recognized upon transfer of control of promised products or services to customers, generally as title and risk of loss passes, in an amount that reflects the consideration the Company expects to receive in exchange for those products or services. Taxes collected from customers, which are subsequently remitted to governmental authorities, are excluded from revenue. Shipping and handling expenses are considered fulfillment activities and are expensed as incurred. The Company’s product portfolio includes various consumer robots, many of which are Wi-Fi connected. The consumer robots are generally highly dependent on, and interrelated with, the embedded software and cannot function without the software. As such, the consumer robots are accounted for as a single performance obligation, and the revenue is recognized at a point in time when the control is transferred to distributors, resellers or directly to end customers through online stores. For consumer robots with Wi-Fi capability ("connected robots"), each sale represents an arrangement with multiple promises consisting of the robot, an app, cloud services and potential future unspecified software upgrades. The Company has determined that the app, cloud services and future unspecified software upgrades represent one promised service to the customer to enhance the functionality and interaction with the robot (referred to collectively as "Cloud Services"). Under the previous revenue accounting standard, revenue allocated to the app and future unspecified software upgrades was deferred and recognized on a straight-line basis over the expected life of the connected robot. Under the newly adopted revenue standard, ASC 606, the Company has concluded that, on a quantitative and qualitative basis, the Cloud Services do not constitute a material performance obligation and, as such, are not considered a separate performance obligation that requires allocation of transaction price. For contracts that contain multiple consumer robots, the transaction price is allocated to each performance obligation based on a relative standalone selling price ("SSP"). The Company’s products generally carry a one-year limited warranty that promises customers that delivered products are as specified. The Company does not consider these assurance-type warranties as a separate performance obligation and therefore, the Company accounts for such warranties under ASC 460, Guarantees. Significant Judgments The Company provides limited rights of returns for direct-to-consumer sales generated through its on-line stores and certain resellers and distributors. In addition, the Company may provide other credits or incentives, including price protection, which are accounted for as variable consideration when estimating the amount of revenue to recognize. Where appropriate, these estimates take into consideration relevant factors such as the Company’s historical experience, current contractual requirements, specific known market events and trends and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates, and the actual amounts of consideration ultimately received may differ from the Company’s estimates. Returns and credits are estimated at contract inception and updated at the end of each reporting period as additional information becomes available and only to the extent that it is probable that a significant reversal of any incremental revenue will not occur. As of March 31, 2018, the Company has reserves for product returns of $38.3 million and other credits and incentives of $38.3 million . As of December 30, 2017, the Company had reserves for product returns of $42.7 million and other credits and incentives of $61.4 million . Disaggregation of Revenue The following table provides information about disaggregated revenue by geographical region for the three months ended March 31, 2018 (in thousands). Three Months Ended March 31, 2018 Americas $ 116,649 EMEA 65,249 APAC 35,170 Total revenue $ 217,068 Contract Balances The following table provides information about receivables, contract assets and contract liabilities from contracts with customers (in thousands): March 31, 2018 (closing balance) December 31, 2017 (opening balance) Accounts receivable, net $ 69,532 $ 141,637 Contract liabilities 6,271 6,685 The Company invoices customers based upon contractual billing schedules, and accounts receivable are recorded when the right to consideration becomes unconditional. Contract liabilities primarily relate to prepayments received from customers in advance of product shipments. The change in the opening and closing balances of the Company’s contract assets and contract liabilities primarily results from the timing difference between the Company’s performance and the customer’s payment. During the three-month period ended March 31, 2018, the Company recognized $6.7 million of the opening contract liability balance as revenue upon transfer of the products to customers. Practical Expedients and Exemptions The Company generally expenses sales commissions when incurred because the amortization period is generally one year or less. These costs are recorded within sales and marketing expenses. The Company does not assess whether a prepayment received represents a significant financing component as the period between when the payment is received and the transfer of the products to the customer is generally one year or less. The Company does not disclose the value of unsatisfied performance obligations for contracts with an original expected duration of one year or less. Financial Statement Impact of Adopting ASC 606 The Company adopted ASC 606 using the modified retrospective method. The cumulative effect of applying the new guidance to all contracts with customers that were not completed as of December 30, 2017 was recorded as an increase of $1.0 million to retained earnings as of the adoption date. The adoption of the new guidance had an immaterial impact to the Company's consolidated balance sheet and statement of income as of and for the three months ended March 31, 2018.

Business Combination (Notes)

Business Combination (Notes)	3 Months Ended
	Mar. 31, 2018
Business Acquisition [Line Items]
Business Combination Disclosure [Text Block]	Business Combination Acquisition of Robopolis On October 2, 2017, the Company closed the acquisition of its largest European distributor, Robopolis SAS, a French company (Robopolis), subsequently renamed iRobot France SAS. The acquisition will better enable the Company to maintain its leadership position and grow its business in several Western European countries through direct control of pre- and post-sales market activities including sales, marketing, branding, channel relationships and customer service. The initial purchase price was approximately $170.1 million in cash, net of acquired cash of $38.0 million , subject to the finalization of the working capital adjustment in accordance with the stock purchase agreement. During the first quarter of 2018, the working capital adjustment was finalized and resulted in a reduction in the purchase price of $0.7 million . The results of operations for this acquisition have been included in the Company’s operating results since the acquisition date. The estimated fair values of assets acquired and liabilities assumed are provisional and are based on the information that was available as of the acquisition date to estimate the fair values. Therefore, the provisional measurements of fair value reflected are subject to change and such changes could be significant. The Company is continuing to analyze certain pre-acquisition income tax filing positions of Robopolis in various taxing jurisdictions that will assist the Company in finalizing the amounts to record for any assumed uncertain income tax positions. The Company expects to finalize the valuation and complete the purchase price allocation as soon as practicable, but no later than one year from the acquisition date. The following table summarizes the preliminary allocation of the purchase price (in thousands): Cash $ 37,981 Accounts receivable 21,426 Inventory 36,304 Goodwill 78,926 Intangible assets 36,597 Other assets 2,456 Total assets acquired 213,690 Accounts payable (29,391 ) Accrued expenses (3,376 ) Deferred tax liabilities (10,864 ) Other liabilities (645 ) Total liabilities assumed (44,276 ) Net assets acquired $ 169,414 The following table reflects the fair value of the acquired identifiable intangible assets and related estimates of useful lives: Useful Life Fair Value (in thousands) Reacquired distribution rights 2.25 years $ 29,296 Customer relationships 14 years 7,029 Non-competition agreements 3 years 272 Total $ 36,597 Pro Forma Results (Unaudited) The following table shows unaudited pro forma results of operations as if the Company had acquired Robopolis on January 1, 2017 (dollars in thousands, except per share amounts): Three Months Ended March 31, 2018 April 1, 2017 Revenue $ 217,068 $ 179,124 Net income 20,401 15,647 Net income per share: Basic income per share $ 0.73 $ 0.57 Diluted income per share $ 0.71 $ 0.55 The unaudited pro forma results of operations are not necessarily indicative of the actual results that would have occurred had the transactions taken place at the beginning of the periods indicated. On April 3, 2017, the Company closed its acquisition of the iRobot-related distribution business of Sales on Demand Corporation ("SODC"). We have not furnished pro forma financial information relating to our acquisition of SODC, because such information is not material, individually or in the aggregate, to our financial results.

Inventory

Inventory	3 Months Ended
	Mar. 31, 2018
Inventory Disclosure [Abstract]
Inventory	Inventory Inventory consists of the following: March 31, 2018 December 30, 2017 (In thousands) Raw materials $ 3,853 $ 4,036 Finished goods 108,258 102,896 $ 112,111 $ 106,932

Goodwill, Other Intangible Asse

Goodwill, Other Intangible Assets and Other Assets	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Other Intangible Assets and Other Assets	Goodwill and Other Intangible Assets The following table summarizes the activity in the carrying amount of goodwill for the three months ended March 31, 2018: (In thousands) Balance as of December 30, 2017 $ 121,440 Purchase accounting adjustments (663 ) Effect of foreign currency translation 2,441 Balance as of March 31, 2018 $ 123,218 Intangible assets at March 31, 2018 and December 30, 2017 consisted of the following: March 31, 2018 December 30, 2017 Cost Accumulated Amortization Net Cost Accumulated Amortization Net (In thousands) Completed technology $ 26,900 $ 19,014 $ 7,886 $ 26,900 $ 18,150 $ 8,750 Tradename 100 100 — 100 100 — Customer relationships 11,766 629 11,137 11,594 418 11,176 Reacquired distribution rights 34,660 13,306 21,354 33,760 9,226 24,534 Non-competition agreements 283 47 236 275 23 252 Total $ 73,709 $ 33,096 $ 40,613 $ 72,629 $ 27,917 $ 44,712 Amortization expense related to acquired intangible assets was $5.2 million and $0.9 million for the three months ended March 31, 2018 and April 1, 2017 , respectively. The estimated future amortization expense related to current intangible assets is expected to be as follows (in thousands): Cost of Revenue Operating Expenses Total Remainder of 2018 $ 14,368 $ 821 $ 15,189 2019 12,397 1,091 13,488 2020 900 1,067 1,967 2021 900 830 1,730 2022 675 829 1,504 Thereafter — 6,735 6,735 Total $ 29,240 $ 11,373 $ 40,613

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2018
Accrued Liabilities, Current [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following at: March 31, 2018 December 30, 2017 (In thousands) Accrued compensation $ 16,387 $ 29,514 Accrued income taxes 12,295 7,110 Accrued warranty 11,833 11,264 Accrued sales and other indirect taxes payable 1,861 7,256 Accrued sales and marketing 1,620 3,299 Accrued accounting fees 1,540 1,221 Accrued direct fulfillment costs 790 1,885 Accrued other 9,781 12,098 $ 56,107 $ 73,647

Derivative Instruments (Notes)

Derivative Instruments (Notes)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Derivative Instruments The Company operates internationally and, in the normal course of business, is exposed to fluctuations in foreign currency exchange rates. The foreign currency exposures typically arise from transactions denominated in currencies other than the functional currency of the Company's operations, primarily the Japanese Yen, Canadian dollar and the Euro. The Company uses derivative instruments that are designated in cash flow hedge relationships to reduce or eliminate the effects of foreign exchange rate changes on purchases and sales. These contracts typically have maturities of thirteen months or less. At March 31, 2018 and December 30, 2017 , the Company had outstanding cash flow hedges with a total notional value of $67.4 million and $73.7 million , respectively. The Company also enters into economic hedges that are not designated as hedges from an accounting standpoint to reduce or eliminate the effects of foreign exchange rate changes typically related to short term trade receivables and payables. These contracts typically have maturities of two months or less. At March 31, 2018 and December 30, 2017 , the Company had outstanding economic hedges with a total notional value of $30.6 million and $36.6 million , respectively. The fair values of derivative instruments are as follows: Fair Value Classification March 31, 2018 December 30, 2017 (In thousands) Derivatives not designated as hedging instruments: Foreign currency forward contracts Other current assets $ — $ 413 Foreign currency forward contracts Accrued expenses 936 221 Derivatives designated as cash flow hedges: Foreign currency forward contracts Other current assets $ 131 $ 488 Foreign currency forward contracts Other assets — 116 Foreign currency forward contracts Accrued expenses 1,676 279 Gains (losses) associated with derivative instruments not designated as hedging instruments are as follows: Three Months Ended Classification March 31, 2018 April 1, 2017 (In thousands) Gain (loss) recognized in income Other income, net $ (1,169 ) $ (225 ) The following tables reflect the effect of foreign exchange forward contracts that are designated as cash flow hedging instruments for the three months ended March 31, 2018 and April 1, 2017 (in thousands): Effective Portion Ineffective Portion Gain (loss) recognized in OCI on Derivative (1) Gain (loss) reclassified from accumulated OCI into income (2) Gain (loss) recognized in income (3) Three months ended Three months ended Three months ended March 31, 2018 April 1, 2017 Classification March 31, 2018 April 1, 2017 Classification March 31, 2018 April 1, 2017 Foreign currency forward contracts $ (2,714 ) $ — Revenue $ (166 ) $ — Other income, net $ (78 ) $ — Cost of revenue $ (755 ) $ — (1) The amount represents the change in fair value of derivative contracts due to changes in spot rates. (2) The amount represents reclassification from other comprehensive income to earnings that occurs when the hedged item affects earnings. (3) The amount represents the change in fair value of derivative contracts due to changes in the forward rates. No gains or losses were reclassified as a result of discontinuance of cash flow hedges.

Fair Value Measurements (Notes)

Fair Value Measurements (Notes)	3 Months Ended
	Mar. 31, 2018
Fair Value Footnote [Abstract]
Fair Value Disclosures [Text Block]	Fair Value Measurements The Company’s financial assets and liabilities measured at fair value on a recurring basis at March 31, 2018 , were as follows: Fair Value Measurements as of March 31, 2018 Level 1 Level 2 (1) Level 3 (In thousands) Assets: Money market funds $ 60,452 $ — $ — Corporate and government bonds, $40,686 at cost (2) — 39,960 — Derivative instruments (Note 8) — 131 — Total assets measured at fair value $ 60,452 $ 40,091 $ — Liabilities: Derivative instruments (Note 8) $ — $ 2,612 $ — Total liabilities measured at fair value $ — $ 2,612 $ — The Company’s financial assets and liabilities measured at fair value on a recurring basis at December 30, 2017 , were as follows: Fair Value Measurements as of Level 1 Level 2 (1) Level 3 (In thousands) Assets: Money market funds $ 3,165 $ — $ — Corporate and government bonds, $37,767 at cost (2) — 37,225 — Derivative instruments (Note 8) — 1,017 — Total assets measured at fair value $ 3,165 $ 38,242 $ — Liabilities: Derivative instruments (Note 8) $ — $ 500 $ — Total liabilities measured at fair value $ — $ 500 $ — (1) Level 2 fair value estimates are based on observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. (2) As of March 31, 2018 , the Company’s investments had maturity dates ranging from June 2018 to March 2021.

Stockholders Equity (Notes)

Stockholders Equity (Notes)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	Stockholders' Equity Share Repurchase Activity On February 27, 2018, the Company's board of directors approved a stock repurchase program authorizing up to $50.0 million in share repurchases. This share repurchase program commenced on March 28, 2018 with an expiration date of December 28, 2018. The Company repurchased 30,000 shares of common stock for $1.9 million under the program during the three months ended March 31, 2018.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings From time to time and in the ordinary course of business, the Company is subject to various claims, charges and litigation. The outcome of litigation cannot be predicted with certainty and some lawsuits, claims or proceedings may be disposed of unfavorably to us, which could materially affect our financial condition or results of operations. Lease Obligations The Company leases its facilities. Rental expense under operating leases for the three months ended March 31, 2018 and April 1, 2017 amounts to $3.2 million and $1.6 million , respectively. Future minimum rental payments under operating leases were as follows as of March 31, 2018 : Operating Leases (In thousands) Remainder of 2018 $ 5,042 2019 7,715 2020 7,370 2021 7,362 2022 7,287 Thereafter 41,893 Total minimum lease payments $ 76,669 Outstanding Purchase Orders At March 31, 2018 , the Company had outstanding purchase orders aggregating approximately $115.9 million . These purchase orders, the majority of which are with contract manufacturers for the purchase of inventory in the normal course of business, are for manufacturing and non-manufacturing related goods and services, and are generally cancelable without penalty. In circumstances where the Company determines that it has financial exposure associated with any of these commitments, the Company records a liability in the period in which that exposure is identified. Guarantees and Indemnification Obligations The Company enters into standard indemnification agreements in the ordinary course of business. Pursuant to these agreements, the Company indemnifies and agrees to reimburse the indemnified party for losses incurred by the indemnified party, generally the Company’s customers, in connection with any patent, copyright, trade secret or other proprietary right infringement claim by any third party. The term of these indemnification agreements is generally perpetual after execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company believes the estimated fair value of these agreements is minimal. Accordingly, the Company has no liabilities recorded for these agreements as of March 31, 2018 and December 30, 2017 , respectively. Warranty The Company provides warranties on most products and has established a reserve for warranty obligations based on estimated warranty costs. The reserve is included as part of accrued expenses (Note 7) in the accompanying consolidated balance sheets. Activity related to the warranty accrual was as follows: Three Months Ended March 31, 2018 April 1, 2017 (In thousands) Balance at beginning of period $ 11,264 $ 8,464 Provision 2,435 1,994 Warranty usage (1) (1,866 ) (1,730 ) Balance at end of period $ 11,833 $ 8,728 (1) Warranty usage includes costs incurred for warranty obligations.

Income Taxes (Notes)

Income Taxes (Notes)	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes The Company’s effective tax rate for the three months ended March 31, 2018 and April 1, 2017, was 21.3% and 24.4% , respectively. On December 22, 2017, the Tax Cuts and Jobs Act of 2017, or the "Act", was signed into law making significant changes to the Internal Revenue Code. Effective for the Company's 2018 tax year, the Act reduces the federal statutory tax rate from 35% to 21% and implements certain additional provisions for the 2018 tax year, including the Global Intangible Low-Taxed Income ("GILTI") inclusion and the Foreign Derived Intangible Income ("FDII") deduction. Due to the timing of the enactment and the complexity involved in applying the provisions of the Act, the Company made reasonable estimates of the effects and recorded a provisional amount relating to the transition tax on the mandatory deemed repatriation of foreign earnings in its financial statements as of December 30, 2017. Additional analysis is necessary to complete the calculation and accounting related to this provisional amount that was recorded in the Company’s financial statements for the year ending December 30, 2017. Based on available guidance released to date, there have been no changes recorded. Any future adjustments to this amount will be recorded to the current income tax provision during the measurement period which is not expected to be beyond one year from the enactment date. The Company's effective tax rate of 21.3% for the three months ended March 31, 2018 differed from the federal statutory tax rate of 21% primarily due to state taxes, partially offset by tax benefits related to excess stock-based compensation. The Company's effective tax rate of 24.4% for the three months ended April 1, 2017 differed from the federal statutory tax rate of 35% primarily due to the recognition of tax benefits related to excess stock-based compensation. The decrease in the effective tax rate for the three months ended March 31, 2018 as compared to the three months ended April 1, 2017 was primarily due to the impacts of the Act, including the reduced federal statutory tax rate partially offset by increased state taxes and decreased tax benefits of excess stock-based compensation.

Industry Segment, Geographic In

Industry Segment, Geographic Information and Significant Customers	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Industry Segment, Geographic Information and Significant Customers	Industry Segment, Geographic Information and Significant Customers The Company operates as one operating segment, consumer robots, the results of which are included in the Company's consolidated statements of income and comprehensive income. The Company's consumer robots products are offered to consumers through a network of retail businesses and one distributor throughout the United States, to various countries through international distributors and retailers, and through the Company's on-line store. Significant Customers For the three months ended March 31, 2018 , the Company generated 11.3% of total revenue from one of its retailers (Amazon). For the three months ended April 1, 2017 , the Company generated 13.5% , 10.5% and 10.0% of total revenue from a network of affiliated European distributors (Robopolis SAS), its distributor in Japan (SODC) and one of its retailers (Bed Bath & Beyond), respectively. On April 3, 2017, the Company acquired the iRobot-related distribution business of SODC, and on October 2, 2017, the Company acquired Robopolis SAS (Note 4).

Summary of Significant Accoun20

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include those of iRobot and its subsidiaries, after elimination of all intercompany balances and transactions. iRobot has prepared the accompanying unaudited consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP). In addition, certain prior year amounts have been reclassified to conform to the current year presentation. In the opinion of management, all adjustments necessary to the unaudited interim consolidated financial statements have been made to state fairly the Company's financial position. Interim results are not necessarily indicative of results for the full fiscal year or any future periods. The information included in this Form 10-Q should be read in conjunction with the Company's audited consolidated financial statements and notes thereto included in its Annual Report on Form 10-K for the fiscal year ended December 30, 2017, filed with the SEC on February 16, 2018.
Use of Estimates	Use of Estimates The preparation of these financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities, revenue and expenses. These estimates and judgments, include but are not limited to, revenue recognition, including performance obligations, variable consideration and other obligations such as product returns and incentives; valuation of goodwill and acquired intangible assets; accounting for business combinations; evaluating loss contingencies; accounting for stock-based compensation including performance-based assessments; and accounting for income taxes and related valuation allowances. The Company bases these estimates and judgments on historical experience, market participant fair value considerations, projected future cash flows and various other factors that the Company believes are reasonable under the circumstances. Actual results may differ from the Company’s estimates.
Fiscal Year-End	Fiscal Year-End The Company operates and reports using a 52 -53 week fiscal year ending on the Saturday closest to December 31. Accordingly, the Company’s fiscal quarters end on the Saturday that falls closest to the last day of the third month of each quarter.
Investment, Policy [Policy Text Block]	Other Assets During the three months ended March 31, 2018, the Company adopted Accounting Standards Update No. 2016-01, "Recognition and Measurement of Financial Assets and Financial Liabilities," which revises the classification and measurement of financial instruments. Upon adoption of this standard, the Company now classifies its cost method investments as equity securities without readily determinable fair values and measures these investments at cost, less any impairment, adjusted for observable price changes. At March 31, 2018 , other assets consisted primarily of equity securities without readily determinable fair values and an equity method investment totaling $14.8 million . There was no adjustment recorded to the carrying value of our equity securities without readily determinable fair values as a result of the adoption of ASU 2016-01. At December 30, 2017 , other assets consisted primarily of cost method investments and an equity method investment totaling $14.2 million .
Net Income Per Share	Net Income Per Share Basic income per share is calculated using the Company's weighted-average outstanding common shares. Diluted income per share is calculated using the Company's weighted-average outstanding common shares including the dilutive effect of stock awards as determined under the treasury stock method. The following table presents the calculation of both basic and diluted net income per share: Three Months Ended (In thousands, except per share amounts) March 31, 2018 April 1, 2017 Net income $ 20,401 $ 16,359 Weighted-average common shares outstanding 27,988 27,304 Dilutive effect of employee stock options and restricted shares 935 991 Diluted weighted-average common shares outstanding 28,923 28,295 Basic income per share $ 0.73 $ 0.60 Diluted income per share $ 0.71 $ 0.58 Restricted stock units and stock options representing approximately 0.1 million and 0.0 million shares of common stock for the three-month periods ended March 31, 2018 and April 1, 2017 , respectively, were excluded from the computation of diluted earnings per share as their effect would have been antidilutive.
Recent Accounting Pronouncements	Recently Adopted Accounting Standards In February 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2018-02, "Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," which provides an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate under the Tax Cuts and Jobs Act is recorded. This guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. During the first quarter of 2018, the Company early adopted this standard, which did not have a material impact on the Company's consolidated financial statements and related disclosures. In October 2016, FASB issued ASU No. 2016-16, "Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory." ASU 2016-16 clarifies the accounting for the current and deferred income taxes for an intra-entity transfer of an asset other than inventory. ASU 2016-16 is effective for fiscal years beginning after December 15, 2017. During the first quarter of 2018, the Company adopted this standard, which did not have a material impact on the Company's consolidated financial statements and related disclosures. In January 2016, the FASB issued ASU No. 2016-01, "Recognition and Measurement of Financial Assets and Financial Liabilities," as amended by ASU No. 2018-03 in February 2018, which revises various aspects of the recognition, measurement, presentation and disclosure of financial instruments. The standard requires that marketable equity investments be measured at fair value with changes to fair value recognized in net income. ASU 2016-01 also provides a new measurement alternative for non-marketable equity investments that do not have a readily determinable fair value. Under the measurement alternative, investments are measured at cost, less any impairment, adjusted for changes from observable transactions for identical or similar investments of the same issuer. The Company adopted this guidance on December 31, 2017 and elected to record its non-marketable equity investments using the alternative measurement method, which did not have a material impact on the Company's consolidated financial statements and related disclosures. In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers," ("ASC 606") which provides guidance for revenue recognition. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. On December 31, 2017, the Company adopted the guidance using the modified retrospective method applied to those contracts that were not completed as of the adoption date. Under the modified retrospective method, the Company recognized the cumulative effect of the adoption and recorded a net increase of $1.0 million to the beginning retained earnings as of December 31, 2017. See Note 3, "Revenue Recognition," for the required disclosures related to the impact of adopting this standard and a discussion of the Company's updated policies related to revenue recognition. Recently Issued Accounting Standards In August 2017, the FASB issued ASU No. 2017-12, "Derivatives and Hedging," that was created to better align accounting rules with a company’s risk management activities, better reflect the economic results of hedging in the financial statements, and simplify hedge accounting treatment. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. For cash flow hedges existing at the adoption date, the standard requires adoption on a modified retrospective basis with a cumulative-effect adjustment to the consolidated balance sheet as of the beginning of the year of adoption. The amendments to presentation guidance and disclosure requirements are required to be adopted prospectively. The Company is currently evaluating the impact of the standard on its consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-08, "Receivables – Nonrefundable Fees and Other Costs," which shortens the amortization period of certain callable debt securities held at a premium. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the standard on its consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, "Measurement of Credit Losses on Financial Instruments," which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses rather than incurred losses to estimate credit losses on certain types of financial instruments. This may result in the earlier recognition of allowances for losses. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the standard on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, "Leases." ASU 2016-02 requires lessees to recognize the assets and liabilities on their balance sheet for the rights and obligations created by most leases and continue to recognize expenses on their income statements over the lease term. It will also require disclosures designed to give financial statement users information on the amount, timing, and uncertainty of cash flows arising from leases. The guidance is effective for annual reporting periods beginning after December 15, 2018 and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the pending adoption of ASU 2016-02 on its consolidated financial statements, and currently expects that most of its operating lease commitments will be subject to the new standard and recognized as operating lease liabilities and right-of-use assets upon its adoption of ASU 2016-02, which will increase the total assets and total liabilities that the Company reports relative to such amounts prior to adoption. From time to time, new accounting pronouncements are issued by FASB that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that recently issued standards, which are not yet effective, will not have a material impact on the Company’s consolidated financial statements upon adoption.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Table Text Block]	Disaggregation of Revenue The following table provides information about disaggregated revenue by geographical region for the three months ended March 31, 2018 (in thousands). Three Months Ended March 31, 2018 Americas $ 116,649 EMEA 65,249 APAC 35,170 Total revenue $ 217,068

Revenue Recognition Contract Ba

Revenue Recognition Contract Balances (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract with Customer, Asset and Liability [Table Text Block]	Contract Balances The following table provides information about receivables, contract assets and contract liabilities from contracts with customers (in thousands): March 31, 2018 (closing balance) December 31, 2017 (opening balance) Accounts receivable, net $ 69,532 $ 141,637 Contract liabilities 6,271 6,685 The Company invoices customers based upon contractual billing schedules, and accounts receivable are recorded when the right to consideration becomes unconditional. Contract liabilities primarily relate to prepayments received from customers in advance of product shipments. The change in the opening and closing balances of the Company’s contract assets and contract liabilities primarily results from the timing difference between the Company’s performance and the customer’s payment. During the three-month period ended March 31, 2018, the Company recognized $6.7 million of the opening contract liability balance as revenue upon transfer of the products to customers.

Business Combination (Tables)

Business Combination (Tables)	3 Months Ended
	Mar. 31, 2018
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The following table summarizes the preliminary allocation of the purchase price (in thousands): Cash $ 37,981 Accounts receivable 21,426 Inventory 36,304 Goodwill 78,926 Intangible assets 36,597 Other assets 2,456 Total assets acquired 213,690 Accounts payable (29,391 ) Accrued expenses (3,376 ) Deferred tax liabilities (10,864 ) Other liabilities (645 ) Total liabilities assumed (44,276 ) Net assets acquired $ 169,414
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	The following table reflects the fair value of the acquired identifiable intangible assets and related estimates of useful lives: Useful Life Fair Value (in thousands) Reacquired distribution rights 2.25 years $ 29,296 Customer relationships 14 years 7,029 Non-competition agreements 3 years 272 Total $ 36,597

Business Combination Business A

Business Combination Business Acq Pro Forma (Tables)	3 Months Ended
	Mar. 31, 2018
Business Combinations Pro Forma [Abstract]
Business Acquisition, Pro Forma Information [Table Text Block]	The following table shows unaudited pro forma results of operations as if the Company had acquired Robopolis on January 1, 2017 (dollars in thousands, except per share amounts): Three Months Ended March 31, 2018 April 1, 2017 Revenue $ 217,068 $ 179,124 Net income 20,401 15,647 Net income per share: Basic income per share $ 0.73 $ 0.57 Diluted income per share $ 0.71 $ 0.55

Inventory (Tables)

Inventory (Tables)	3 Months Ended
	Mar. 31, 2018
Inventory Disclosure [Abstract]
Components of Inventory	Inventory Inventory consists of the following: March 31, 2018 December 30, 2017 (In thousands) Raw materials $ 3,853 $ 4,036 Finished goods 108,258 102,896 $ 112,111 $ 106,932

Goodwill, Other Intangible As26

Goodwill, Other Intangible Assets and Other Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	The following table summarizes the activity in the carrying amount of goodwill for the three months ended March 31, 2018: (In thousands) Balance as of December 30, 2017 $ 121,440 Purchase accounting adjustments (663 ) Effect of foreign currency translation 2,441 Balance as of March 31, 2018 $ 123,218
Other Intangible Assets	Intangible assets at March 31, 2018 and December 30, 2017 consisted of the following: March 31, 2018 December 30, 2017 Cost Accumulated Amortization Net Cost Accumulated Amortization Net (In thousands) Completed technology $ 26,900 $ 19,014 $ 7,886 $ 26,900 $ 18,150 $ 8,750 Tradename 100 100 — 100 100 — Customer relationships 11,766 629 11,137 11,594 418 11,176 Reacquired distribution rights 34,660 13,306 21,354 33,760 9,226 24,534 Non-competition agreements 283 47 236 275 23 252 Total $ 73,709 $ 33,096 $ 40,613 $ 72,629 $ 27,917 $ 44,712
Estimated Future Amortization Expense Related to Current Intangible Assets	The estimated future amortization expense related to current intangible assets is expected to be as follows (in thousands): Cost of Revenue Operating Expenses Total Remainder of 2018 $ 14,368 $ 821 $ 15,189 2019 12,397 1,091 13,488 2020 900 1,067 1,967 2021 900 830 1,730 2022 675 829 1,504 Thereafter — 6,735 6,735 Total $ 29,240 $ 11,373 $ 40,613

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2018
Accrued Liabilities, Current [Abstract]
Components of Accrued Expenses	Accrued expenses consist of the following at: March 31, 2018 December 30, 2017 (In thousands) Accrued compensation $ 16,387 $ 29,514 Accrued income taxes 12,295 7,110 Accrued warranty 11,833 11,264 Accrued sales and other indirect taxes payable 1,861 7,256 Accrued sales and marketing 1,620 3,299 Accrued accounting fees 1,540 1,221 Accrued direct fulfillment costs 790 1,885 Accrued other 9,781 12,098 $ 56,107 $ 73,647

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) [Table Text Block]	Gains (losses) associated with derivative instruments not designated as hedging instruments are as follows: Three Months Ended Classification March 31, 2018 April 1, 2017 (In thousands) Gain (loss) recognized in income Other income, net $ (1,169 ) $ (225 ) The following tables reflect the effect of foreign exchange forward contracts that are designated as cash flow hedging instruments for the three months ended March 31, 2018 and April 1, 2017 (in thousands): Effective Portion Ineffective Portion Gain (loss) recognized in OCI on Derivative (1) Gain (loss) reclassified from accumulated OCI into income (2) Gain (loss) recognized in income (3) Three months ended Three months ended Three months ended March 31, 2018 April 1, 2017 Classification March 31, 2018 April 1, 2017 Classification March 31, 2018 April 1, 2017 Foreign currency forward contracts $ (2,714 ) $ — Revenue $ (166 ) $ — Other income, net $ (78 ) $ — Cost of revenue $ (755 ) $ — (1) The amount represents the change in fair value of derivative contracts due to changes in spot rates. (2) The amount represents reclassification from other comprehensive income to earnings that occurs when the hedged item affects earnings. (3) The amount represents the change in fair value of derivative contracts due to changes in the forward rates. No gains or losses were reclassified as a result of discontinuance of cash flow hedges.

Derivative Instruments Schedule

Derivative Instruments Schedule of Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative [Line Items]
Schedule of Derivative Instruments [Table Text Block]	The fair values of derivative instruments are as follows: Fair Value Classification March 31, 2018 December 30, 2017 (In thousands) Derivatives not designated as hedging instruments: Foreign currency forward contracts Other current assets $ — $ 413 Foreign currency forward contracts Accrued expenses 936 221 Derivatives designated as cash flow hedges: Foreign currency forward contracts Other current assets $ 131 $ 488 Foreign currency forward contracts Other assets — 116 Foreign currency forward contracts Accrued expenses 1,676 279

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	The Company’s financial assets and liabilities measured at fair value on a recurring basis at March 31, 2018 , were as follows: Fair Value Measurements as of March 31, 2018 Level 1 Level 2 (1) Level 3 (In thousands) Assets: Money market funds $ 60,452 $ — $ — Corporate and government bonds, $40,686 at cost (2) — 39,960 — Derivative instruments (Note 8) — 131 — Total assets measured at fair value $ 60,452 $ 40,091 $ — Liabilities: Derivative instruments (Note 8) $ — $ 2,612 $ — Total liabilities measured at fair value $ — $ 2,612 $ — The Company’s financial assets and liabilities measured at fair value on a recurring basis at December 30, 2017 , were as follows: Fair Value Measurements as of Level 1 Level 2 (1) Level 3 (In thousands) Assets: Money market funds $ 3,165 $ — $ — Corporate and government bonds, $37,767 at cost (2) — 37,225 — Derivative instruments (Note 8) — 1,017 — Total assets measured at fair value $ 3,165 $ 38,242 $ — Liabilities: Derivative instruments (Note 8) $ — $ 500 $ — Total liabilities measured at fair value $ — $ 500 $ — (1) Level 2 fair value estimates are based on observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. (2) As of March 31, 2018 , the Company’s investments had maturity dates ranging from June 2018 to March 2021.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Summary of Future Minimum Rental Payments under Operating Leases	Future minimum rental payments under operating leases were as follows as of March 31, 2018 : Operating Leases (In thousands) Remainder of 2018 $ 5,042 2019 7,715 2020 7,370 2021 7,362 2022 7,287 Thereafter 41,893 Total minimum lease payments $ 76,669
Activity Related to the Warranty Accrual	Activity related to the warranty accrual was as follows: Three Months Ended March 31, 2018 April 1, 2017 (In thousands) Balance at beginning of period $ 11,264 $ 8,464 Provision 2,435 1,994 Warranty usage (1) (1,866 ) (1,730 ) Balance at end of period $ 11,833 $ 8,728 (1) Warranty usage includes costs incurred for warranty obligations.

Industry Segment, Geographic 32

Industry Segment, Geographic Information and Significant Customers (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Segment Information about Revenue, Cost of Revenue, Gross Margin and Income before Income Taxes	The Company operates as one operating segment, consumer robots, the results of which are included in the Company's consolidated statements of income and comprehensive income. The Company's consumer robots products are offered to consumers through a network of retail businesses and one distributor throughout the United States, to various countries through international distributors and retailers, and through the Company's on-line store.

Summary of Significant Accoun33

Summary of Significant Accounting Policies - Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]
Net income	$ 20,401	$ 16,359
Weighted-average shares outstanding	27,988	27,304
Dilutive effect of employee stock options and restricted shares	935	991
Diluted weighted-average shares outstanding	28,923	28,295
Basic income per share	$ 0.73	$ 0.60
Diluted income per share	$ 0.71	$ 0.58
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	100	0

Summary of Significant Accoun34

Summary of Significant Accounting Policies Revenue Recognition (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 30, 2017
Allowance for Sales Returns [Member]
Valuation Allowances and Reserves, Balance	$ 38.3	$ 42.7
Allowance for Promotions [Member]
Valuation Allowances and Reserves, Balance	$ 38.3	$ 61.4

Summary of Significant Accoun35

Summary of Significant Accounting Policies Other Assets (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 30, 2017
Equity and cost method investments [Abstract]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	$ 14.8	$ 14.2

Revenue Recognition (Details)

Revenue Recognition (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 217,068
Americas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	116,649
EMEA [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	65,249
Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 35,170

Revenue Recognition Contract 37

Revenue Recognition Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 30, 2017
Revenue from Contract with Customer [Abstract]
Contract with Customer, Timing of Satisfaction of Performance Obligation and Payment	$ 6,700
Accounts receivable, net	69,532	$ 141,637	$ 142,829
Contract liabilities	$ 6,271	$ 6,685

Revenue Recognition Accounts Re

Revenue Recognition Accounts Receivable Allowances (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 30, 2017
Allowance for Sales Returns [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance	$ 38.3	$ 42.7
Allowance for Promotions [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance	$ 38.3	$ 61.4

Business Combination (Details)

Business Combination (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 02, 2017	Mar. 31, 2018	Apr. 01, 2017	Dec. 30, 2017
Business Acquisition [Line Items]
Revenue, Net		$ 217,068	$ 168,467
Goodwill		$ 123,218		$ 121,440
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 0.73	$ 0.57
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0.71	$ 0.55
Goodwill, Purchase Accounting Adjustments		$ 663
Business Acquisition, Pro Forma Revenue			$ 179,124
Net income		$ 20,401	16,359
Business Acquisition, Pro Forma Net Income (Loss)			$ 15,647
Robopolis [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 170,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities	(10,864)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	(645)
Cash Acquired from Acquisition	37,981
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	36,304
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	2,456
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	213,690
Goodwill	78,926
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	36,597
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	169,414
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	21,426
Finite-lived Intangible Assets Acquired	36,597
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities	(29,391)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities	(3,376)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	44,276
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Cash Acquired from Acquisition	$ 38,000
Distribution Rights [Member] | Robopolis [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years 3 months
Finite-lived Intangible Assets Acquired	$ 29,296
Customer Relationships [Member] | Robopolis [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	14 years
Finite-lived Intangible Assets Acquired	$ 7,029
Noncompete Agreements [Member] | Robopolis [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years
Finite-lived Intangible Assets Acquired	$ 272

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 30, 2017
Inventory Disclosure [Abstract]
Inventory, Raw Materials, Net of Reserves	$ 3,853	$ 4,036
Inventory, Finished Goods, Net of Reserves	108,258	102,896
Inventory	$ 112,111	$ 106,932

Goodwill, Other Intangible As41

Goodwill, Other Intangible Assets and Other Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Dec. 30, 2017
Business Acquisition [Line Items]
Goodwill	$ 123,218		$ 121,440
Amortization of Acquired Intangible Assets	$ 5,200	$ 900

Goodwill, Other Intangible As42

Goodwill, Other Intangible Assets and Other Assets - Other Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Dec. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 73,709		$ 72,629
Intangible assets accumulated amortization	33,096		27,917
Intangible Assets, Net	40,613		44,712
Amortization of Acquired Intangible Assets	5,200	$ 900
Completed technology
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	26,900		26,900
Intangible assets accumulated amortization	19,014		18,150
Intangible Assets, Net	7,886		8,750
Trade Names
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	100		100
Intangible assets accumulated amortization	100		100
Intangible Assets, Net	0		0
Customer-Related Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	11,766		11,594
Intangible assets accumulated amortization	629		418
Intangible Assets, Net	11,137		11,176
Distribution Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	34,660		33,760
Intangible assets accumulated amortization	13,306		9,226
Intangible Assets, Net	21,354		24,534
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	283		275
Intangible assets accumulated amortization	47		23
Intangible Assets, Net	$ 236		$ 252

Goodwill, Other Intangible As43

Goodwill, Other Intangible Assets and Other Assets Schedule of goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 30, 2017
Goodwill [Line Items]
Goodwill	$ 123,218	$ 121,440
Goodwill, Acquired During Period	(663)
Goodwill, Foreign Currency Translation Gain (Loss)	$ 2,441

Goodwill, Other Intangible As44

Goodwill, Other Intangible Assets and Other Assets Finite-lived intangible assets, schedule of future amortization (Details) $ in Thousands	Mar. 31, 2018USD ($)
Finite-lived intangible assets, schedule of amortization expense [Line Items]
Remainder of 2018	$ 15,189
2,019	13,488
2,020	1,967
2,021	1,730
2,022	1,504
Thereafter	6,735
Total	40,613
Cost of revenue
Finite-lived intangible assets, schedule of amortization expense [Line Items]
Remainder of 2018	14,368
2,019	12,397
2,020	900
2,021	900
2,022	675
Thereafter	0
Total	29,240
Operating Expense [Member]
Finite-lived intangible assets, schedule of amortization expense [Line Items]
Remainder of 2018	821
2,019	1,091
2,020	1,067
2,021	830
2,022	829
Thereafter	6,735
Total	$ 11,373

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 30, 2017
Accrued Liabilities, Current [Abstract]
Other Employee-related Liabilities, Current	$ 16,387	$ 29,514
Accounts Payable, Current [Abstract]
Accrued warranty	11,833	11,264
Accrued sales and other taxes payable	1,861	7,256
Accrued sales and marketing	1,620	3,299
Accrued accounting fees	1,540	1,221
Accrued direct fulfillment costs	790	1,885
Accrued federal and state income taxes	12,295	7,110
Accrued other	9,781	12,098
Accrued expenses	$ 56,107	$ 73,647

Derivative Instruments Schedu46

Derivative Instruments Schedule of Derivative Instruments (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Apr. 01, 2017	Dec. 30, 2017
Derivative [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments		$ (1,169)	$ (225)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	[1]	(78)	$ 0
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount		67,400		$ 73,700
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount		30,600		36,600
Accrued Liabilities [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net		936		221
Derivative, Fair Value, Net		1,676		279
Other Current Assets [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net		0		413
Derivative, Fair Value, Net		131		488
Other Assets [Member] | Foreign Exchange Forward [Member]
Derivative [Line Items]
Derivative, Fair Value, Net		$ 0		$ 116
[1]	(3)The amount represents the change in fair value of derivative contracts due to changes in the forward rates. No gains or losses were reclassified as a result of discontinuance of cash flow hedges.

Derivative Instruments (Details

Derivative Instruments (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Apr. 01, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	[1]	$ (78)	$ 0
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion	[2]	(2,714)	0
Sales Revenue, Net [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[3]	(166)	0
Cost of revenue | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[3]	$ (755)	$ 0
[1]	(3)The amount represents the change in fair value of derivative contracts due to changes in the forward rates. No gains or losses were reclassified as a result of discontinuance of cash flow hedges.
[2]	(1)The amount represents the change in fair value of derivative contracts due to changes in spot rates.
[3]	(2)The amount represents reclassification from other comprehensive income to earnings that occurs when the hedged item affects earnings.

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	[1]	$ 40,686	$ 37,767
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		60,452	3,165
Available-for-sale Securities		0	0
Derivative Asset		0	0
Assets, Fair Value Disclosure		60,452	3,165
Derivative Liability		0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[2]	0	0
Available-for-sale Securities	[1],[2]	39,960	37,225
Derivative Asset	[2]	131	1,017
Assets, Fair Value Disclosure	[2]	40,091	38,242
Derivative Liability	[2]	2,612	500
Financial and Nonfinancial Liabilities, Fair Value Disclosure	[2]	2,612	500
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		0	0
Available-for-sale Securities		0	0
Derivative Asset		0	0
Assets, Fair Value Disclosure		0	0
Derivative Liability		0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure		$ 0	$ 0
[1]	(2)As of March 31, 2018, the Company’s investments had maturity dates ranging from June 2018 to March 2021.
[2]	(1)Level 2 fair value estimates are based on observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Stockholders Equity (Details)

Stockholders Equity (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Feb. 27, 2018
Equity [Abstract]
Stock Repurchase Program, Authorized Amount		$ 50,000,000
Stock Repurchased and Retired During Period, Shares	30,000
Stock Repurchased and Retired During Period, Value	$ 1,900,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	Mar. 31, 2018USD ($)
Outstanding POs [Abstract]
Contractual Obligation	$ 115.9

Commitments and Contingencies51

Commitments and Contingencies - Summary of Future Minimum Rental Payments under Operating Leases (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Commitments and Contingencies Disclosure [Abstract]
Rental expense under operating leases	$ 3,200	$ 1,600
Disclosure Summary Of Future Minimum Rental Payments Under Operating Leases [Abstract]
Remainder of 2018	5,042
2,019	7,715
2,020	7,370
2,021	7,362
2,022	7,287
Thereafter	41,893
Total minimum lease payments	$ 76,669

Commitments and Contingencies52

Commitments and Contingencies - Activity Related to Warranty Accrual (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Apr. 01, 2017
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period		$ 11,264	$ 8,464
Provision		2,435	1,994
Warranty usage	[1]	(1,866)	(1,730)
Balance at end of period		$ 11,833	$ 8,728
[1]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjQxODk3YjkyZGRhMzQxMWI5ZjM0ZDYzY2E5NmRhNzI4fFRleHRTZWxlY3Rpb246N0NGNTQ3MjU3NkFEMzBGMEZCNkZGODRENDdGN0Q4NDQM}

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	21.30%	24.40%

Industry Segment, Geographic 54

Industry Segment, Geographic Information and Significant Customers - Segment Information about Revenue, Cost of Revenue, Gross Margin and Income before Income Taxes (Detail) $ in Thousands		3 Months Ended
		Mar. 31, 2018USD ($)segment	Apr. 01, 2017USD ($)
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Number of Reportable Segments | segment		1
Revenue		$ 217,068	$ 168,467
Cost of revenue	[1]	101,283	81,124
Gross margin		115,785	87,343
Research and development	[1]	32,945	25,508
Selling and marketing	[1]	31,329	22,575
General and administrative	[1]	25,833	17,622
Other income, net		519	3
Income before income taxes		$ 25,924	$ 21,641
[1]	(1)Stock-based compensation recorded in the three months ended March 31, 2018 and April 1, 2017 breaks down by expense classification as follows: Three Months Ended March 31, 2018 April 1, 2017Cost of revenue$341 $226Research and development1,689 1,099Selling and marketing738 570General and administrative3,178 2,436

Industry Segment, Geographic 55

Industry Segment, Geographic Information and Significant Customers - Additional Information (Detail) - Customer Concentration Risk [Member]	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Robopolis SAS [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration Risk, Percentage		13.50%
Sales On Demand Corporation (SODC) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration Risk, Percentage		10.50%
Sales Revenue, Net [Member] | One Customer [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration Risk, Percentage	11.30%
Sales Revenue, Net [Member] | two customer [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration Risk, Percentage		10.00%