iRobot (IRBT) 10-Q 30 Oct 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 26, 2015	Oct. 26, 2015
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 26, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Trading Symbol	IRBT
Entity Registrant Name	IROBOT CORP
Entity Central Index Key	1,159,167
Current Fiscal Year End Date	--01-02
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		29,069,589

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Current assets:
Cash and cash equivalents	$ 176,430	$ 185,957
Short term investments	35,791	36,166
Accounts receivable, net of allowance of $66 at September 26, 2015 and $67 at December 27, 2014	76,314	71,056
Unbilled revenue	580	2,614
Inventory	58,665	47,857
Deferred tax assets	20,338	21,505
Other current assets	8,408	9,704
Total current assets	376,526	374,859
Property and equipment, net	28,553	31,297
Deferred tax assets	7,688	8,409
Goodwill	48,751	48,751
Intangible assets, net	16,529	19,146
Other assets	11,766	10,751
Total assets	489,813	493,213
Current liabilities:
Accounts payable	56,490	60,256
Accrued expenses	13,752	18,701
Accrued compensation	11,153	16,235
Deferred revenue and customer advances	2,279	3,849
Total current liabilities	83,674	99,041
Long term liabilities	$ 3,033	$ 3,736
Commitments and contingencies (Note 7)
Redeemable convertible preferred stock, 5,000,000 shares authorized and none outstanding	$ 0	$ 0
Common stock, $0.01 par value, 100,000,000 shares authorized; 29,247,802 and 29,644,602 shares issued and outstanding at September 26, 2015 and December 27, 2014, respectively	292	297
Additional paid-in capital	237,260	249,409
Retained earnings	165,680	140,881
Accumulated other comprehensive loss	(126)	(151)
Total stockholders’ equity	403,106	390,436
Total liabilities, redeemable convertible preferred stock and stockholders’ equity	$ 489,813	$ 493,213

Consolidated Balance Sheets (U3

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Net allowances on Accounts receivables	$ 66	$ 67
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	28,247,802	29,644,602
Common stock, shares outstanding	28,247,802	29,644,602

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Revenue		$ 143,609	$ 143,497	$ 410,358	$ 397,504
Cost of revenue (1)	[1]	73,751	75,608	216,759	215,784
Gross margin		69,858	67,889	193,599	181,720
Operating expenses:
Research and development (1)	[1]	18,122	17,343	55,886	51,522
Selling and marketing (1)	[1]	19,379	15,844	60,896	53,911
General and administrative (1)	[1]	13,701	12,008	39,195	35,938
Total operating expenses		51,202	45,195	155,977	141,371
Operating income		18,656	22,694	37,622	40,349
Other expense, net		(93)	(374)	(948)	(469)
Income before income taxes		18,563	22,320	36,674	39,880
Income tax expense		5,770	7,713	11,875	11,463
Net income		$ 12,793	$ 14,607	$ 24,799	$ 28,417
Net income per share
Basic		$ 0.43	$ 0.49	$ 0.84	$ 0.97
Diluted		$ 0.42	$ 0.48	$ 0.82	$ 0.94
Number of weighted average common shares used in calculations per share
Basic		29,654	29,595	29,697	29,439
Diluted		30,117	30,183	30,253	30,169
Stock-based compensation				$ 10,462	$ 10,016
Cost of revenue
Number of weighted average common shares used in calculations per share
Stock-based compensation		$ 270	$ 291	662	626
Research and development
Number of weighted average common shares used in calculations per share
Stock-based compensation		963	866	2,737	2,425
Selling and marketing
Number of weighted average common shares used in calculations per share
Stock-based compensation		474	319	1,089	860
General and administrative
Number of weighted average common shares used in calculations per share
Stock-based compensation		$ 2,193	$ 2,315	$ 5,974	$ 6,105
[1]	Total stock-based compensation recorded in the three and nine months ended September 26, 2015 and September 27, 2014 included in the above figures breaks down by expense classification as follows: Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014Cost of revenue$270 $291 $662 $626Research and development963 866 2,737 2,425Selling and marketing474 319 1,089 860General and administrative2,193 2,315 5,974 6,105

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Net income	$ 12,793	$ 14,607	$ 24,799	$ 28,417
Other comprehensive income, net of tax:
Unrealized gains/(losses) on investments, net of tax	67	(80)	25	(171)
Total comprehensive income	$ 12,860	$ 14,527	$ 24,824	$ 28,246

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014
Cash flows from operating activities:
Net income	$ 24,799	$ 28,417
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	10,569	9,578
Loss on disposal of assets	201	27
Stock-based compensation	10,462	10,016
Deferred income taxes, net	2,289	793
Tax benefit of excess stock-based compensation deductions	(795)	(2,707)
Non-cash director deferred compensation	112	34
Changes in operating assets and liabilities - (use) source
Accounts receivable	(5,258)	(28,999)
Unbilled revenue	2,034	(323)
Inventory	(10,965)	(8,678)
Other assets	1,296	(5,407)
Accounts payable	(1,285)	4,943
Accrued expenses	(6,127)	2,859
Accrued compensation	(5,082)	(7,836)
Deferred revenue and customer advances	(1,570)	(2,376)
Long term liabilities	(703)	(467)
Net cash provided by (used in) operating activities	19,977	(126)
Cash flows from investing activities:
Additions of property and equipment	(7,557)	(9,168)
Change in other assets	1,015	0
Purchases of investments	(17,755)	(24,214)
Sales of investments	18,000	7,500
Net cash used in investing activities	(8,327)	(25,882)
Cash flows from financing activities:
Proceeds from stock option exercises	3,385	7,853
Income tax withholding payment associated with restricted stock vesting	(1,295)	(1,532)
Stock repurchases	(24,062)	0
Tax benefit of excess stock-based compensation deductions	795	2,707
Net cash provided by (used in) financing activities	(21,177)	9,028
Net decrease in cash and cash equivalents	(9,527)	(16,980)
Cash and cash equivalents, at beginning of period	185,957	165,404
Cash and cash equivalents, at end of period	176,430	148,424
Supplemental disclosure of cash flow information:
Cash paid for income taxes	8,791	15,462
Noncash portion of stock repurchases	1,156	0
Transfer of inventory to property and equipment	157	637
Additions of property and equipment included in accounts payable	$ 754	$ 671

Description of Business

Description of Business	9 Months Ended
	Sep. 26, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business iRobot Corporation (“iRobot” or the “Company”) develops robotics and artificial intelligence technologies and applies these technologies in producing and marketing robots. The Company’s revenue is primarily generated from product sales.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 26, 2015
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 accounts and transactions. In addition, certain prior year amounts have been reclassified to conform to the current year presentation. iRobot has prepared the accompanying unaudited consolidated financial statements in conformity with accounting principles generally accepted in the United States of America. The accompanying unaudited financial data as of September 26, 2015 and for the three and nine months ended September 26, 2015 and September 27, 2014 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. The year-end balance sheet data were derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States. These consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto included in its Annual Report on Form 10-K for the fiscal year ended December 27, 2014 , filed with the SEC on February 13, 2015. In the opinion of management, all adjustments necessary to state fairly the Company's statement of financial position as of September 26, 2015 and results of operations and cash flows for the periods ended September 26, 2015 and September 27, 2014 have been made. The results of operations and cash flows for any interim period are not necessarily indicative of the operating results and cash flows for the full fiscal year or any future periods. Use of Estimates The preparation of these financial statements in conformity with accounting principles generally accepted in the United States requires the Company to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and disclosure of contingent assets and liabilities. On an ongoing basis, management evaluates these estimates and judgments, including those related to revenue recognition, sales returns, bad debts, warranty claims, inventory reserves, valuation of investments, valuation of goodwill and intangible assets, assumptions used in valuing stock-based compensation instruments and income taxes. The Company bases these estimates on historical and anticipated results and trends and on various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. By their nature, estimates are subject to an inherent degree of uncertainty. 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. Revenue Recognition The Company derives its revenue primarily from product sales and, to a lesser extent, government and commercial research and development contracts. The Company sells products directly to customers and indirectly through resellers and distributors. The Company recognizes revenue from sales of robots under the terms of the customer agreement upon transfer of title and risk of loss to the customer, net of estimated returns, provided that collection is determined to be reasonably assured and no significant obligations remain. Beginning in the third quarter of 2015, with the introduction of the Company's first connected robot, each sale of a connected robot represents a multi-element arrangement containing the robot, an app and potential future unspecified software upgrades. Revenue is allocated to the deliverables based on their relative selling prices which have been determined using best estimate of selling price (BESP). Revenue allocated to the app and unspecified software upgrades is then deferred and recognized on a straight-line basis over the period in which the Company expects to provide the upgrades over the estimated life of the robot. Sales to domestic and Canadian resellers of home robots are typically subject to agreements allowing for limited rights of return, rebates and price protection. The Company also provides limited rights of returns for direct-to-consumer sales generated through its on-line stores. Accordingly, the Company reduces revenue for its estimates of liabilities for these rights of return, rebates and price protection at the time the related sale is recorded. These estimates for rights of return are directly based on specific terms and conditions included in the reseller agreements, historical returns experience and various other assumptions that the Company believes are reasonable under the circumstances. In the case of new product introductions, the estimates for returns applied to the new products are based upon the estimates for the most similar predecessor products until such time that the Company has enough actual returns experience for the new products, which is typically two holiday returns cycles. At that time, the Company incorporates that data into the development of returns estimates for the new products. The Company updates its analysis of returns on a quarterly basis. If actual returns differ significantly from the Company's estimates, or if modifications to individual reseller agreements are entered into that impact their rights of returns, such differences could result in an adjustment to previously established reserves and could have a material impact, either favorably or unfavorably, on the Company’s results of operations for the period in which the actual returns become known or the reseller agreement is modified. The Company's international distributor agreements do not currently allow for product returns and, as a result, no reserve for returns is established for this group of customers. The estimates and reserve for rebates and price protection are based on specific programs, expected usage and historical experience. Actual results could differ from these estimates. Under cost-plus-fixed-fee (CPFF) type contracts, the Company recognizes revenue based on costs incurred plus a pro rata portion of the total fixed fee. Costs incurred include labor and material that are directly associated with individual CPFF contracts plus indirect overhead and general and administrative type costs based upon billing rates submitted by the Company to the Defense Contract Management Agency (DCMA). Annually, the Company submits final indirect billing rates to DCMA based upon actual costs incurred throughout the year. In the situation where the Company’s final actual billing rates are greater than the estimated rates currently in effect, the Company records a cumulative revenue adjustment in the period in which the rate differential is collected from the customer. These final billing rates are subject to audit by the Defense Contract Audit Agency (DCAA), which can occur several years after the final billing rates are submitted and may result in material adjustments to revenue recognized based on estimated final billing rates. As of September 26, 2015 , fiscal years 2012 through 2014 are open for audit by DCAA. In the situation where the Company’s anticipated actual billing rates will be lower than the provisional rates currently in effect, the Company records a cumulative revenue adjustment in the period in which the rate differential is identified. Revenue on firm fixed price (FFP) contracts is recognized using the percentage-of-completion method. For government product FFP contracts, revenue is recognized as the product is shipped or in accordance with the contract terms. Costs and estimated gross margins on contracts are recorded as revenue as work is performed based on the percentage that incurred costs compare to estimated total costs utilizing the most recent estimates of costs and funding. Changes in job performance, job conditions, and estimated profitability, including those arising from final contract settlements and government audits, may result in revisions to costs and income and are recognized in the period in which the revisions are determined. Since many contracts extend over a long period of time, revisions in cost and funding estimates during the progress of work have the effect of adjusting earnings applicable to past performance in the current period. When the current contract estimate indicates a loss, a provision is made for the total anticipated loss in the current period. Revenue earned in excess of billings, if any, is recorded as unbilled revenue. Billings in excess of revenue earned, if any, are recorded as deferred revenue. Stock-Based Compensation The Company accounts for stock-based compensation through recognition of the fair value of the stock-based compensation as a charge against earnings. Stock-based compensation cost for stock options is estimated at the grant date based on each option's fair value as calculated by the Black-Scholes option-pricing model. Stock-based compensation cost for restricted stock awards, time-based restricted stock units and performance-based restricted stock units is measured based on the closing fair market value of the Company's common stock on the date of grant. For performance-based restricted stock units, the compensation costs will be subsequently adjusted for assumptions of achievement during the period in which the assumption of achievement changes, as applicable. The Company recognizes stock-based compensation as expense ratably on a straight-line basis over the requisite service period, net of estimated forfeitures. Net Income Per Share The following table presents the calculation of both basic and diluted net income per share: Three Months Ended Nine Months Ended (In thousands, except per share amounts) September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Net income $ 12,793 $ 14,607 $ 24,799 $ 28,417 Weighted-average shares outstanding 29,654 29,595 29,697 29,439 Dilutive effect of employee stock options and restricted shares 463 588 556 730 Diluted weighted-average shares outstanding 30,117 30,183 30,253 30,169 Basic income per share $ 0.43 $ 0.49 $ 0.84 $ 0.97 Diluted income per share $ 0.42 $ 0.48 $ 0.82 $ 0.94 Restricted stock units and stock options representing approximately 0.7 million and 0.4 million shares of common stock for the three month periods ended September 26, 2015 and September 27, 2014 , respectively, and approximately 0.5 million and 0.2 million shares of common stock for the nine month periods ended September 26, 2015 and September 27, 2014 , respectively, were excluded from the computation of diluted earnings per share for these periods because their effect would have been antidilutive. Income Taxes The Company is subject to taxation in the United States and various states and foreign jurisdictions. The statute of limitations for examinations by the Internal Revenue Service is closed for fiscal years prior to 2012. The statute of limitations for examinations by state tax authorities is closed for fiscal years prior to 2011. Federal carryforward attributes that were generated prior to fiscal year 2012 and state carryforward attributes that were generated prior to fiscal year 2011 may still be adjusted upon examination by the federal or state tax authorities if they either have been or will be used in a period for which the statute of limitations is still open. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company monitors the realization of its deferred tax assets based on changes in circumstances, for example recurring periods of income for tax purposes following historical periods of cumulative losses, generation of tax credits compared to future utilization of credits, or changes in tax laws or regulations. The Company's income tax provision and its assessment of the ability to realize its deferred tax assets involve significant judgments and estimates. The Company is currently generating state research credits that exceed the amount being utilized. As a result of this trend, a valuation allowance may be needed in the future related to these state tax credits. The Company recorded a tax provision of $5.8 million and $7.7 million for the three month periods ended September 26, 2015 and September 27, 2014 , respectively. The $5.8 million provision for the three month period ended September 26, 2015 resulted in an effective income tax rate of 31.1% . The $7.7 million provision for the three month period ended September 27, 2014 resulted in an effective income tax rate of 34.6% . The difference between the effective income tax rate of 31.1% for the three month period ended September 26, 2015 and 34.6% for the three month period ended September 27, 2014 was primarily due to an increase in 2014 federal research and development tax credits generated upon the filing of the 2014 federal income tax return during the three month period ended September 26, 2015, partially offset by an increase in state income taxes. The 2014 federal research and development tax credit was enacted in the fourth fiscal quarter of 2014 and the Company recorded the associated estimated benefit for the full year in that period. As the federal research and development tax credit was not in effect for the three month period ended September 27, 2014 and has not been enacted for 2015, the effective income tax rates for the three month periods ended September 26, 2015 and September 27, 2014 do not include any benefit for the federal research and development tax credit. The Company recorded a tax provision of $11.9 million and $11.5 million for the nine month periods ended September 26, 2015 and September 27, 2014 , respectively. The $11.9 million provision for the nine month period ended September 26, 2015 resulted in an effective income tax rate of 32.4% . The $11.5 million provision for the nine month period ended September 27, 2014 resulted in an effective income tax rate of 28.7% . The difference between the effective income tax rate of 32.4% for the nine month period ended September 26, 2015 and 28.7% for the nine month period ended September 27, 2014 was primarily due to an increase in state income taxes during the nine month period ended September 26, 2015, as compared to September 27, 2014, and the release of $2.1 million of valuation allowance related to certain tax attributes of Evolution Robotics, Inc. during the nine month period ended September 27, 2014, partially offset by an increase in 2014 federal research and development tax credits generated upon the filing of the 2014 federal income tax return during the nine month period ended September 26, 2015. The 2014 federal research and development tax credit was enacted in the fourth fiscal quarter of 2014 and the Company recorded the associated estimated benefit for the full year in that period. As the federal research and development tax credit was not in effect for the nine month period ended September 27, 2014 and has not been enacted for 2015, the effective income tax rates for the nine month periods ended September 26, 2015 and September 27, 2014 do not include any benefit for the federal research and development tax credit. Fair Value Measurements The authoritative guidance for fair value establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. Financial Assets and Liabilities The Company’s financial assets and liabilities measured at fair value on a recurring basis at September 26, 2015 , were as follows: Fair Value Measurements as of September 26, 2015 Level 1 Level 2 Level 3 (In thousands) Description Assets: Cash and cash equivalents Money market funds $ 108,100 $ — $ — Short term investments Corporate and government bonds (1) — 35,791 — Total assets measured at fair value $ 108,100 $ 35,791 $ — Liabilities: Accrued expenses Derivative instruments (Note 6) (2) $ — $ 16 $ — Total liabilities measured at fair value $ — $ 16 $ — The Company’s financial assets measured at fair value on a recurring basis at December 27, 2014 , were as follows: Fair Value Measurements as of Level 1 Level 2 Level 3 (In thousands) Description Assets: Cash and cash equivalents Money market funds $ 109,843 $ — $ — Short term investments Corporate and government bonds (1) — 36,166 — Total assets measured at fair value $ 109,843 $ 36,166 $ — (1) The bond investments are valued based on observable market values as of the Company’s reporting date. The bond investments are recorded at fair value and marked-to-market at the end of each reporting period. The realized and unrealized gains and losses are included in comprehensive income for that period. (2) Derivative instruments are valued using an income approach based on the present value of the forward rate less the contract rate multiplied by the notional amount. Goodwill Goodwill is recorded as the difference, if any, between the aggregate consideration paid for an acquisition and the fair value of the net tangible and intangible assets acquired. The Company evaluates goodwill for impairment at the reporting unit level (operating segment or one level below an operating segment) annually or more frequently if the Company believes indicators of impairment exist. In accordance with applicable guidance, the Company is permitted to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the Company concludes that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, then a two-step goodwill impairment test is performed. The first step of the impairment test involves comparing the fair values of the applicable reporting units with their aggregate carrying values, including goodwill. If the carrying amount of a reporting unit exceeds the reporting unit’s fair value, the Company performs the second step of the goodwill impairment test to determine the amount of impairment loss. The second step of the goodwill impairment test involves comparing the implied fair value of the affected reporting unit’s goodwill with the carrying value of that goodwill. The Company completes the annual impairment evaluation during the fourth quarter of each year. Recent Accounting Pronouncements In July 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2015-11, “Inventory: Simplifying the Measurement of Inventory.” ASU No. 2015-11 applies only to inventory for which cost is determined by methods other than last-in, first-out and the retail inventory method, which includes inventory that is measured using first-in, first-out or average cost. Inventory within the scope of this standard is required to be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The new standard will be effective for the Company on January 1, 2017. The Company is currently assessing the potential impact of ASU No. 2015-11 on its consolidated financial statements. In April 2015, the FASB issued ASU No. 2015-05, “Intangibles - Goodwill and Other - Internal-Use Software: Customer's Accounting for Fees Paid in a Cloud Computing Arrangement.” Under ASU No. 2015-05, if a cloud computing arrangement includes a software license, the software license element of the arrangement should be accounted for consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the arrangement should be accounted for as a service contract. The new standard will be effective for the Company on January 3, 2016. The Company is currently assessing the potential impact of ASU No. 2015-05 on its consolidated financial statements. In February 2015, the FASB issued ASU 2015-02, “Consolidation - Amendments to the Consolidation Analysis.” ASU No. 2015-02 reduces the number of consolidation models and changes the way reporting entities evaluate a variable interest entity. It is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted. The Company is currently assessing the potential impact of ASU No. 2015-02 on its consolidated financial statements. In August 2014, the FASB issued ASU No. 2014-15, “Presentation of Financial Statements - Going Concern.” ASU No. 2014-15 requires management of public and private companies to evaluate whether there is substantial doubt about the entity’s ability to continue as a going concern and, if so, disclose that fact. Management will also be required to evaluate and disclose whether its plans alleviate that doubt. The new standard is effective for annual periods ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016. The Company does not believe that the impact of this amendment will be material to the Company’s consolidated financial statements. In June 2014, the FASB issued ASU No. 2014-12, “Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period.” ASU No. 2014-12 requires a reporting entity to treat a performance target that affects vesting and that could be achieved after the requisite service period as a performance condition. It is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted. The Company is currently assessing the potential impact of ASU No. 2014-12 on its consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers,” 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. The new guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. In July 2015, the FASB voted to defer the effective date of the new accounting guidance related to revenue recognition by one year to December 17, 2017 for annual reporting periods beginning after that date and permitted early adoption of the standard, but not before the original effective date of December 15, 2016. The Company is in the process of evaluating the impact that the adoption of the new revenue recognition standard issued in May 2014 will have on its consolidated financial statements and footnote disclosures. 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.

Inventory

Inventory	9 Months Ended
	Sep. 26, 2015
Inventory Disclosure [Abstract]
Inventory	Inventory Inventory consists of the following: September 26, 2015 December 27, 2014 (In thousands) Raw materials $ 7,780 $ 9,455 Finished goods 50,885 38,402 $ 58,665 $ 47,857

Stock Option Plans

Stock Option Plans	9 Months Ended
	Sep. 26, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option Plans	Stock Option and Incentive Plans The Company has awards outstanding under three stock incentive plans: the 2005 Stock Option and Incentive Plan (the "2005 Plan"), the Evolution Robotics, Inc. 2007 Stock Plan (the "2007 Plan") and the 2015 Stock Option and Incentive Plan (the "2015 Plan" and together with the 2005 Plan and the 2007 Plan, the “Plans”). The 2015 Plan is the only one of the three plans under which new awards may currently be granted. Under the 2015 Plan, which became effective May 20, 2015 , 3,100,000 shares were initially reserved for issuance in the form of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units, unrestricted stock awards, cash-based awards, performance share awards and dividend equivalent rights. Stock awards returned to the Plans, with the exception of those issued under the 2007 Plan, as a result of their expiration, cancellation or termination are automatically made available for issuance under the 2015 Plan. Eligibility for incentive stock options is limited to those individuals whose employment status would qualify them for the tax treatment associated with incentive stock options in accordance with the Internal Revenue Code of 1986, as amended. As of September 26, 2015 , there were 2,551,119 shares available for future grant under the 2015 Plan. Awards granted under the Plans are subject to terms and conditions as determined by the compensation committee of the board of directors, including vesting periods. Options granted under the Plans are exercisable in full at any time subsequent to vesting, generally vest over periods from one to five years, and expire five or ten years from the date of grant or, if earlier, 60 or 90 days from employee termination. The exercise price of stock options is equal to the closing price on the NASDAQ Global Market on the date of grant. Other awards granted under the Plans generally vest over periods from one to three years. On September 4, 2015, the Company granted to certain employees stock options totaling 77,725 shares of the Company's common stock and 216,478 restricted stock units. Each of the above stock options have a per share exercise price of $29.60 , the closing price of the Company's common stock on NASDAQ on September 4, 2015.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 26, 2015
Accrued Liabilities, Current [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following: September 26, 2015 December 27, 2014 (In thousands) Accrued warranty $ 6,876 $ 7,769 Accrued rent 677 701 Accrued direct fulfillment costs 781 1,346 Accrued customer deposits 769 702 Accrued sales tax 557 867 Accrued accounting fees 434 167 Accrued sales commissions 304 531 Accrued other 3,354 6,618 $ 13,752 $ 18,701 Accrued compensation consists of the following at: September 26, 2015 December 27, 2014 (In thousands) Accrued bonus $ 4,714 $ 8,455 Accrued other compensation 6,439 7,780 $ 11,153 $ 16,235

Derivative Instruments (Notes)

Derivative Instruments (Notes)	9 Months Ended
	Sep. 26, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Derivative Instruments The Company is exposed to adverse changes in foreign currency exchange rates, primarily related to sales in the Canadian Dollar and the Euro. As a result, the Company periodically enters into foreign currency forward contracts to minimize the impact of fluctuating exchange rates on results of operations. These derivative instruments have maturities of two months or less and have not qualified for hedge accounting. Notional amounts and fair values of derivative instruments are as follows: Notional amount Fair Value Classification September 26, 2015 December 27, 2014 September 26, 2015 December 27, 2014 (In thousands) Foreign currency forward contracts Accrued expenses $ 3,417 $ — $ 16 $ — Gains/(losses) associated with derivative instruments are as follows: Three Months Ended Nine Months Ended Classification September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 (In thousands) Derivatives not designated as hedging instruments Gain (loss) recognized in income Other expense, net $ 191 $ — $ (1 ) $ —

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 26, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Obligations Rental expense under operating leases for the three months ended September 26, 2015 and September 27, 2014 were $1.2 million and $1.2 million , respectively, and for the nine months ended September 26, 2015 and September 27, 2014 were $3.6 million and $3.6 million , respectively. Future minimum rental payments under operating leases were as follows as of September 26, 2015 : Operating Leases (In thousands) Remainder of 2015 $ 942 2016 3,873 2017 3,427 2018 2,959 2019 2,925 Thereafter 978 Total minimum lease payments $ 15,104 Outstanding Purchase Orders At September 26, 2015 , the Company had outstanding purchase orders aggregating approximately $109 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 we determine that we have financial exposure associated with any of these commitments, we record 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 with respect to the Company’s products. 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 September 26, 2015 and December 27, 2014 , respectively. Warranty The Company provides warranties on most products and has established a reserve for warranties based on identified or estimated warranty costs. The reserve is included as part of accrued expenses (Note 5) in the accompanying balance sheets. Activity related to the warranty accrual was as follows: Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 (In thousands) (In thousands) Balance at beginning of period $ 7,081 $ 7,602 $ 7,769 $ 6,497 Provision 1,031 1,679 3,182 5,444 Warranty usage(1) (1,236 ) (1,356 ) (4,075 ) (4,016 ) Balance at end of period $ 6,876 $ 7,925 $ 6,876 $ 7,925 (1) Warranty usage includes costs incurred for warranty obligations. Sales Taxes The Company collects and remits sales tax in jurisdictions in which it has a physical presence or it believes nexus exists, which therefore obligates the Company to collect and remit sales tax. The Company continually evaluates whether it has established nexus in new jurisdictions with respect to sales tax. The Company has recorded a liability for potential exposure in certain states where there is uncertainty about the point in time at which the Company established a sufficient business connection to create nexus. The Company continues to analyze possible sales tax exposure, but does not currently believe that any individual claim or aggregate claims that might arise will ultimately have a material effect on its consolidated results of operations, financial position or cash flows.

Industry Segment, Geographic In

Industry Segment, Geographic Information and Significant Customers	9 Months Ended
	Sep. 26, 2015
Segment Reporting [Abstract]
Industry Segment, Geographic Information and Significant Customers	Industry Segment, Geographic Information and Significant Customers The Company operates in two reportable segments, the home robots business unit and the defense and security robots business unit. The nature of products and types of customers for the two segments vary significantly. As such, the segments are managed separately. Home Robots The Company’s home robots business unit offers products to consumers through a network of retail businesses throughout the United States, to various countries through international distributors and retailers, and through the Company’s on-line store. The Company’s home robots business unit includes mobile robots used in the maintenance of households. Defense and Security The Company’s defense and security robots business unit offers products to the U.S. Department of Defense through a small U.S. government-focused sales force and distributors, and to other North American and international entities through small domestic and international sales teams, as well as through North American and international distributors. The Company’s defense and security robots are used to increase warfighters', law enforcement's, security forces' and first responders' safety and productivity. Other The Company’s other revenue and cost of revenue result from other smaller business units that do not meet the criteria of a reportable segment, as well as other operational costs not directly attributable to the home robots or defense and security reportable segments included in cost of revenue. The table below presents segment information about revenue, cost of revenue, gross margin and income before income taxes: Three Months Ended Nine Months Ended (In thousands) September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Revenue: Home Robots $ 136,513 $ 132,013 $ 384,422 $ 373,283 Defense & Security 6,184 10,667 24,500 21,369 Other (1) 912 817 1,436 2,852 Total revenue 143,609 143,497 410,358 397,504 Cost of revenue: Home Robots 64,512 65,135 185,677 186,991 Defense & Security 3,533 4,977 14,700 11,725 Other (2) 5,706 5,496 16,382 17,068 Total cost of revenue 73,751 75,608 216,759 215,784 Gross margin: Home Robots 72,001 66,878 198,745 186,292 Defense & Security 2,651 5,690 9,800 9,644 Other (4,794 ) (4,679 ) (14,946 ) (14,216 ) Total gross margin 69,858 67,889 193,599 181,720 Research and development 18,122 17,343 55,886 51,522 Selling and marketing 19,379 15,844 60,896 53,911 General and administrative 13,701 12,008 39,195 35,938 Other expense, net (93 ) (374 ) (948 ) (469 ) Income before income taxes $ 18,563 $ 22,320 $ 36,674 $ 39,880 (1) Other revenue results from other smaller business units that do not meet the criteria of a reportable segment. (2) Other cost of revenue results from other smaller business units that do not meet the criteria of a reportable segment, as well as other operational costs not directly attributable to the home robots or defense and security reportable segments. Geographic Information For the three months ended September 26, 2015 and September 27, 2014 , sales to non-U.S. customers accounted for 55.9% and 63.4% of total revenue, respectively, and sales to non-U.S. customers for the nine months ended September 26, 2015 and September 27, 2014 accounted for 60.3% and 64.2% of total revenue, respectively. Significant Customers For the three months ended September 26, 2015 , the Company generated 16.5% and 11.4% , respectively, of total revenue from two of its international distributors of home robots products and 10.2% from one of its domestic retailers of home robots products. For the three months ended September 27, 2014 , the Company generated 17.5% and 14.0% , respectively, of total revenue from two of its international distributors of home robots products. For the nine months ended September 26, 2015 , the Company generated 14.9% and 12.9% , respectively, of total revenue from two of its international distributors of home robot products. For the nine months ended September 27, 2014 , the Company generated 19.1% and 13.2% , respectively, of total revenue from two of its international distributors of home robots products.

Goodwill, Other Intangible Asse

Goodwill, Other Intangible Assets and Other Assets	9 Months Ended
	Sep. 26, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Other Intangible Assets and Other Assets	Goodwill and Other Intangible Assets Goodwill The carrying amount of the Company's goodwill at September 26, 2015 is $48.8 million , of which $41.1 million resulted from the acquisition of Evolution Robotics, Inc. in October 2012 and was assigned to the home robots reporting unit. $7.7 million resulted from the acquisition of Nekton Research, LLC completed in September 2008 and was assigned to the defense and security reporting unit. Other Intangible Assets Other intangible assets include the value assigned to completed technology and a trade name. The estimated useful lives for all of these intangible assets are three to ten years. The intangible assets are being amortized on a straight-line basis, which is consistent with the pattern that the economic benefits of the intangible assets are expected to be utilized. Intangible assets at September 26, 2015 and December 27, 2014 consisted of the following: September 26, 2015 December 27, 2014 Cost Accumulated Amortization Net Cost Accumulated Amortization Impairment Loss Net (In thousands) Completed technology $ 26,900 $ 10,371 $ 16,529 $ 30,600 $ 9,691 1,788 $ 19,121 Research contracts — — — 100 100 — — Tradename 100 100 — 800 775 — 25 Total $ 27,000 $ 10,471 $ 16,529 $ 31,500 $ 10,566 $ 1,788 $ 19,146 During the three month period ended March 28, 2015, the Company removed fully amortized intangible assets from its consolidated balance sheet. Amortization expense related to acquired intangible assets was $0.9 million and $0.9 million for the three months ended September 26, 2015 and September 27, 2014 , respectively. Amortization expense related to acquired intangible assets was $2.6 million and $2.7 million for the nine months ended September 26, 2015 and September 27, 2014 , respectively. The estimated future amortization expense is expected to be as follows: (In thousands) Remainder of 2015 $ 864 2016 3,457 2017 3,457 2018 3,457 2019 2,818 Thereafter 2,476 Total $ 16,529

Subsequent Event (Notes)

Subsequent Event (Notes)	9 Months Ended
	Sep. 26, 2015
Subsequent Event [Line Items]
Subsequent Events [Text Block]	Subsequent Event In October 2015, the Company received proceeds of approximately $5.6 million in conjunction with the sale of a majority of its preferred shares in a cost-method investment. The Company expects to record a pre-tax gain of approximately $3.0 million , or $0.06 per share, related to the sale of these preferred shares in the fourth quarter of 2015.

Summary of Significant Accoun17

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 26, 2015
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 accounts and transactions. In addition, certain prior year amounts have been reclassified to conform to the current year presentation. iRobot has prepared the accompanying unaudited consolidated financial statements in conformity with accounting principles generally accepted in the United States of America. The accompanying unaudited financial data as of September 26, 2015 and for the three and nine months ended September 26, 2015 and September 27, 2014 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. The year-end balance sheet data were derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States. These consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto included in its Annual Report on Form 10-K for the fiscal year ended December 27, 2014 , filed with the SEC on February 13, 2015. In the opinion of management, all adjustments necessary to state fairly the Company's statement of financial position as of September 26, 2015 and results of operations and cash flows for the periods ended September 26, 2015 and September 27, 2014 have been made. The results of operations and cash flows for any interim period are not necessarily indicative of the operating results and cash flows for the full fiscal year or any future periods.
Use of Estimates	Use of Estimates The preparation of these financial statements in conformity with accounting principles generally accepted in the United States requires the Company to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and disclosure of contingent assets and liabilities. On an ongoing basis, management evaluates these estimates and judgments, including those related to revenue recognition, sales returns, bad debts, warranty claims, inventory reserves, valuation of investments, valuation of goodwill and intangible assets, assumptions used in valuing stock-based compensation instruments and income taxes. The Company bases these estimates on historical and anticipated results and trends and on various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. By their nature, estimates are subject to an inherent degree of uncertainty. 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.
Revenue Recognition	Revenue Recognition The Company derives its revenue primarily from product sales and, to a lesser extent, government and commercial research and development contracts. The Company sells products directly to customers and indirectly through resellers and distributors. The Company recognizes revenue from sales of robots under the terms of the customer agreement upon transfer of title and risk of loss to the customer, net of estimated returns, provided that collection is determined to be reasonably assured and no significant obligations remain. Beginning in the third quarter of 2015, with the introduction of the Company's first connected robot, each sale of a connected robot represents a multi-element arrangement containing the robot, an app and potential future unspecified software upgrades. Revenue is allocated to the deliverables based on their relative selling prices which have been determined using best estimate of selling price (BESP). Revenue allocated to the app and unspecified software upgrades is then deferred and recognized on a straight-line basis over the period in which the Company expects to provide the upgrades over the estimated life of the robot. Sales to domestic and Canadian resellers of home robots are typically subject to agreements allowing for limited rights of return, rebates and price protection. The Company also provides limited rights of returns for direct-to-consumer sales generated through its on-line stores. Accordingly, the Company reduces revenue for its estimates of liabilities for these rights of return, rebates and price protection at the time the related sale is recorded. These estimates for rights of return are directly based on specific terms and conditions included in the reseller agreements, historical returns experience and various other assumptions that the Company believes are reasonable under the circumstances. In the case of new product introductions, the estimates for returns applied to the new products are based upon the estimates for the most similar predecessor products until such time that the Company has enough actual returns experience for the new products, which is typically two holiday returns cycles. At that time, the Company incorporates that data into the development of returns estimates for the new products. The Company updates its analysis of returns on a quarterly basis. If actual returns differ significantly from the Company's estimates, or if modifications to individual reseller agreements are entered into that impact their rights of returns, such differences could result in an adjustment to previously established reserves and could have a material impact, either favorably or unfavorably, on the Company’s results of operations for the period in which the actual returns become known or the reseller agreement is modified. The Company's international distributor agreements do not currently allow for product returns and, as a result, no reserve for returns is established for this group of customers. The estimates and reserve for rebates and price protection are based on specific programs, expected usage and historical experience. Actual results could differ from these estimates. Under cost-plus-fixed-fee (CPFF) type contracts, the Company recognizes revenue based on costs incurred plus a pro rata portion of the total fixed fee. Costs incurred include labor and material that are directly associated with individual CPFF contracts plus indirect overhead and general and administrative type costs based upon billing rates submitted by the Company to the Defense Contract Management Agency (DCMA). Annually, the Company submits final indirect billing rates to DCMA based upon actual costs incurred throughout the year. In the situation where the Company’s final actual billing rates are greater than the estimated rates currently in effect, the Company records a cumulative revenue adjustment in the period in which the rate differential is collected from the customer. These final billing rates are subject to audit by the Defense Contract Audit Agency (DCAA), which can occur several years after the final billing rates are submitted and may result in material adjustments to revenue recognized based on estimated final billing rates. As of September 26, 2015 , fiscal years 2012 through 2014 are open for audit by DCAA. In the situation where the Company’s anticipated actual billing rates will be lower than the provisional rates currently in effect, the Company records a cumulative revenue adjustment in the period in which the rate differential is identified. Revenue on firm fixed price (FFP) contracts is recognized using the percentage-of-completion method. For government product FFP contracts, revenue is recognized as the product is shipped or in accordance with the contract terms. Costs and estimated gross margins on contracts are recorded as revenue as work is performed based on the percentage that incurred costs compare to estimated total costs utilizing the most recent estimates of costs and funding. Changes in job performance, job conditions, and estimated profitability, including those arising from final contract settlements and government audits, may result in revisions to costs and income and are recognized in the period in which the revisions are determined. Since many contracts extend over a long period of time, revisions in cost and funding estimates during the progress of work have the effect of adjusting earnings applicable to past performance in the current period. When the current contract estimate indicates a loss, a provision is made for the total anticipated loss in the current period. Revenue earned in excess of billings, if any, is recorded as unbilled revenue. Billings in excess of revenue earned, if any, are recorded as deferred revenue.
Accounting for Share-Based Payments	Stock-Based Compensation The Company accounts for stock-based compensation through recognition of the fair value of the stock-based compensation as a charge against earnings. Stock-based compensation cost for stock options is estimated at the grant date based on each option's fair value as calculated by the Black-Scholes option-pricing model. Stock-based compensation cost for restricted stock awards, time-based restricted stock units and performance-based restricted stock units is measured based on the closing fair market value of the Company's common stock on the date of grant. For performance-based restricted stock units, the compensation costs will be subsequently adjusted for assumptions of achievement during the period in which the assumption of achievement changes, as applicable. The Company recognizes stock-based compensation as expense ratably on a straight-line basis over the requisite service period, net of estimated forfeitures.
Net Income Per Share	Net Income Per Share The following table presents the calculation of both basic and diluted net income per share: Three Months Ended Nine Months Ended (In thousands, except per share amounts) September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Net income $ 12,793 $ 14,607 $ 24,799 $ 28,417 Weighted-average shares outstanding 29,654 29,595 29,697 29,439 Dilutive effect of employee stock options and restricted shares 463 588 556 730 Diluted weighted-average shares outstanding 30,117 30,183 30,253 30,169 Basic income per share $ 0.43 $ 0.49 $ 0.84 $ 0.97 Diluted income per share $ 0.42 $ 0.48 $ 0.82 $ 0.94 Restricted stock units and stock options representing approximately 0.7 million and 0.4 million shares of common stock for the three month periods ended September 26, 2015 and September 27, 2014 , respectively, and approximately 0.5 million and 0.2 million shares of common stock for the nine month periods ended September 26, 2015 and September 27, 2014 , respectively, were excluded from the computation of diluted earnings per share for these periods because their effect would have been antidilutive.
Income Taxes	Income Taxes The Company is subject to taxation in the United States and various states and foreign jurisdictions. The statute of limitations for examinations by the Internal Revenue Service is closed for fiscal years prior to 2012. The statute of limitations for examinations by state tax authorities is closed for fiscal years prior to 2011. Federal carryforward attributes that were generated prior to fiscal year 2012 and state carryforward attributes that were generated prior to fiscal year 2011 may still be adjusted upon examination by the federal or state tax authorities if they either have been or will be used in a period for which the statute of limitations is still open. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company monitors the realization of its deferred tax assets based on changes in circumstances, for example recurring periods of income for tax purposes following historical periods of cumulative losses, generation of tax credits compared to future utilization of credits, or changes in tax laws or regulations. The Company's income tax provision and its assessment of the ability to realize its deferred tax assets involve significant judgments and estimates. The Company is currently generating state research credits that exceed the amount being utilized. As a result of this trend, a valuation allowance may be needed in the future related to these state tax credits. The Company recorded a tax provision of $5.8 million and $7.7 million for the three month periods ended September 26, 2015 and September 27, 2014 , respectively. The $5.8 million provision for the three month period ended September 26, 2015 resulted in an effective income tax rate of 31.1% . The $7.7 million provision for the three month period ended September 27, 2014 resulted in an effective income tax rate of 34.6% . The difference between the effective income tax rate of 31.1% for the three month period ended September 26, 2015 and 34.6% for the three month period ended September 27, 2014 was primarily due to an increase in 2014 federal research and development tax credits generated upon the filing of the 2014 federal income tax return during the three month period ended September 26, 2015, partially offset by an increase in state income taxes. The 2014 federal research and development tax credit was enacted in the fourth fiscal quarter of 2014 and the Company recorded the associated estimated benefit for the full year in that period. As the federal research and development tax credit was not in effect for the three month period ended September 27, 2014 and has not been enacted for 2015, the effective income tax rates for the three month periods ended September 26, 2015 and September 27, 2014 do not include any benefit for the federal research and development tax credit. The Company recorded a tax provision of $11.9 million and $11.5 million for the nine month periods ended September 26, 2015 and September 27, 2014 , respectively. The $11.9 million provision for the nine month period ended September 26, 2015 resulted in an effective income tax rate of 32.4% . The $11.5 million provision for the nine month period ended September 27, 2014 resulted in an effective income tax rate of 28.7% . The difference between the effective income tax rate of 32.4% for the nine month period ended September 26, 2015 and 28.7% for the nine month period ended September 27, 2014 was primarily due to an increase in state income taxes during the nine month period ended September 26, 2015, as compared to September 27, 2014, and the release of $2.1 million of valuation allowance related to certain tax attributes of Evolution Robotics, Inc. during the nine month period ended September 27, 2014, partially offset by an increase in 2014 federal research and development tax credits generated upon the filing of the 2014 federal income tax return during the nine month period ended September 26, 2015. The 2014 federal research and development tax credit was enacted in the fourth fiscal quarter of 2014 and the Company recorded the associated estimated benefit for the full year in that period. As the federal research and development tax credit was not in effect for the nine month period ended September 27, 2014 and has not been enacted for 2015, the effective income tax rates for the nine month periods ended September 26, 2015 and September 27, 2014 do not include any benefit for the federal research and development tax credit.
Fair Value Measurement, Policy [Policy Text Block]	Fair Value Measurements The authoritative guidance for fair value establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. Financial Assets and Liabilities The Company’s financial assets and liabilities measured at fair value on a recurring basis at September 26, 2015 , were as follows: Fair Value Measurements as of September 26, 2015 Level 1 Level 2 Level 3 (In thousands) Description Assets: Cash and cash equivalents Money market funds $ 108,100 $ — $ — Short term investments Corporate and government bonds (1) — 35,791 — Total assets measured at fair value $ 108,100 $ 35,791 $ — Liabilities: Accrued expenses Derivative instruments (Note 6) (2) $ — $ 16 $ — Total liabilities measured at fair value $ — $ 16 $ — The Company’s financial assets measured at fair value on a recurring basis at December 27, 2014 , were as follows: Fair Value Measurements as of Level 1 Level 2 Level 3 (In thousands) Description Assets: Cash and cash equivalents Money market funds $ 109,843 $ — $ — Short term investments Corporate and government bonds (1) — 36,166 — Total assets measured at fair value $ 109,843 $ 36,166 $ — (1) The bond investments are valued based on observable market values as of the Company’s reporting date. The bond investments are recorded at fair value and marked-to-market at the end of each reporting period. The realized and unrealized gains and losses are included in comprehensive income for that period. (2) Derivative instruments are valued using an income approach based on the present value of the forward rate less the contract rate multiplied by the notional amount.
Goodwill	Goodwill Goodwill is recorded as the difference, if any, between the aggregate consideration paid for an acquisition and the fair value of the net tangible and intangible assets acquired. The Company evaluates goodwill for impairment at the reporting unit level (operating segment or one level below an operating segment) annually or more frequently if the Company believes indicators of impairment exist. In accordance with applicable guidance, the Company is permitted to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the Company concludes that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, then a two-step goodwill impairment test is performed. The first step of the impairment test involves comparing the fair values of the applicable reporting units with their aggregate carrying values, including goodwill. If the carrying amount of a reporting unit exceeds the reporting unit’s fair value, the Company performs the second step of the goodwill impairment test to determine the amount of impairment loss. The second step of the goodwill impairment test involves comparing the implied fair value of the affected reporting unit’s goodwill with the carrying value of that goodwill. The Company completes the annual impairment evaluation during the fourth quarter of each year.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In July 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2015-11, “Inventory: Simplifying the Measurement of Inventory.” ASU No. 2015-11 applies only to inventory for which cost is determined by methods other than last-in, first-out and the retail inventory method, which includes inventory that is measured using first-in, first-out or average cost. Inventory within the scope of this standard is required to be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The new standard will be effective for the Company on January 1, 2017. The Company is currently assessing the potential impact of ASU No. 2015-11 on its consolidated financial statements. In April 2015, the FASB issued ASU No. 2015-05, “Intangibles - Goodwill and Other - Internal-Use Software: Customer's Accounting for Fees Paid in a Cloud Computing Arrangement.” Under ASU No. 2015-05, if a cloud computing arrangement includes a software license, the software license element of the arrangement should be accounted for consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the arrangement should be accounted for as a service contract. The new standard will be effective for the Company on January 3, 2016. The Company is currently assessing the potential impact of ASU No. 2015-05 on its consolidated financial statements. In February 2015, the FASB issued ASU 2015-02, “Consolidation - Amendments to the Consolidation Analysis.” ASU No. 2015-02 reduces the number of consolidation models and changes the way reporting entities evaluate a variable interest entity. It is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted. The Company is currently assessing the potential impact of ASU No. 2015-02 on its consolidated financial statements. In August 2014, the FASB issued ASU No. 2014-15, “Presentation of Financial Statements - Going Concern.” ASU No. 2014-15 requires management of public and private companies to evaluate whether there is substantial doubt about the entity’s ability to continue as a going concern and, if so, disclose that fact. Management will also be required to evaluate and disclose whether its plans alleviate that doubt. The new standard is effective for annual periods ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016. The Company does not believe that the impact of this amendment will be material to the Company’s consolidated financial statements. In June 2014, the FASB issued ASU No. 2014-12, “Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period.” ASU No. 2014-12 requires a reporting entity to treat a performance target that affects vesting and that could be achieved after the requisite service period as a performance condition. It is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted. The Company is currently assessing the potential impact of ASU No. 2014-12 on its consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers,” 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. The new guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. In July 2015, the FASB voted to defer the effective date of the new accounting guidance related to revenue recognition by one year to December 17, 2017 for annual reporting periods beginning after that date and permitted early adoption of the standard, but not before the original effective date of December 15, 2016. The Company is in the process of evaluating the impact that the adoption of the new revenue recognition standard issued in May 2014 will have on its consolidated financial statements and footnote disclosures. 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.

Summary of Significant Accoun18

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 26, 2015
Accounting Policies [Abstract]
Basic and Diluted Net Income Per Share	The following table presents the calculation of both basic and diluted net income per share: Three Months Ended Nine Months Ended (In thousands, except per share amounts) September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Net income $ 12,793 $ 14,607 $ 24,799 $ 28,417 Weighted-average shares outstanding 29,654 29,595 29,697 29,439 Dilutive effect of employee stock options and restricted shares 463 588 556 730 Diluted weighted-average shares outstanding 30,117 30,183 30,253 30,169 Basic income per share $ 0.43 $ 0.49 $ 0.84 $ 0.97 Diluted income per share $ 0.42 $ 0.48 $ 0.82 $ 0.94
Fair Value Assets Measured on Recurring Basis	The Company’s financial assets and liabilities measured at fair value on a recurring basis at September 26, 2015 , were as follows: Fair Value Measurements as of September 26, 2015 Level 1 Level 2 Level 3 (In thousands) Description Assets: Cash and cash equivalents Money market funds $ 108,100 $ — $ — Short term investments Corporate and government bonds (1) — 35,791 — Total assets measured at fair value $ 108,100 $ 35,791 $ — Liabilities: Accrued expenses Derivative instruments (Note 6) (2) $ — $ 16 $ — Total liabilities measured at fair value $ — $ 16 $ — The Company’s financial assets measured at fair value on a recurring basis at December 27, 2014 , were as follows: Fair Value Measurements as of Level 1 Level 2 Level 3 (In thousands) Description Assets: Cash and cash equivalents Money market funds $ 109,843 $ — $ — Short term investments Corporate and government bonds (1) — 36,166 — Total assets measured at fair value $ 109,843 $ 36,166 $ — (1) The bond investments are valued based on observable market values as of the Company’s reporting date. The bond investments are recorded at fair value and marked-to-market at the end of each reporting period. The realized and unrealized gains and losses are included in comprehensive income for that period. (2) Derivative instruments are valued using an income approach based on the present value of the forward rate less the contract rate multiplied by the notional amount.

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 26, 2015
Inventory Disclosure [Abstract]
Components of Inventory	Inventory consists of the following: September 26, 2015 December 27, 2014 (In thousands) Raw materials $ 7,780 $ 9,455 Finished goods 50,885 38,402 $ 58,665 $ 47,857

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 26, 2015
Accrued Liabilities, Current [Abstract]
Components of Accrued Expenses	Accrued expenses consist of the following: September 26, 2015 December 27, 2014 (In thousands) Accrued warranty $ 6,876 $ 7,769 Accrued rent 677 701 Accrued direct fulfillment costs 781 1,346 Accrued customer deposits 769 702 Accrued sales tax 557 867 Accrued accounting fees 434 167 Accrued sales commissions 304 531 Accrued other 3,354 6,618 $ 13,752 $ 18,701 Accrued compensation consists of the following at: September 26, 2015 December 27, 2014 (In thousands) Accrued bonus $ 4,714 $ 8,455 Accrued other compensation 6,439 7,780 $ 11,153 $ 16,235

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 26, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) [Table Text Block]	Gains/(losses) associated with derivative instruments are as follows: Three Months Ended Nine Months Ended Classification September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 (In thousands) Derivatives not designated as hedging instruments Gain (loss) recognized in income Other expense, net $ 191 $ — $ (1 ) $ —

Derivative Instruments Schedule

Derivative Instruments Schedule of Derivative Instruments (Tables)	9 Months Ended
	Sep. 26, 2015
Derivative [Line Items]
Schedule of Derivative Instruments [Table Text Block]	Notional amounts and fair values of derivative instruments are as follows: Notional amount Fair Value Classification September 26, 2015 December 27, 2014 September 26, 2015 December 27, 2014 (In thousands) Foreign currency forward contracts Accrued expenses $ 3,417 $ — $ 16 $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 26, 2015
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 September 26, 2015 : Operating Leases (In thousands) Remainder of 2015 $ 942 2016 3,873 2017 3,427 2018 2,959 2019 2,925 Thereafter 978 Total minimum lease payments $ 15,104
Activity Related to the Warranty Accrual	Activity related to the warranty accrual was as follows: Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 (In thousands) (In thousands) Balance at beginning of period $ 7,081 $ 7,602 $ 7,769 $ 6,497 Provision 1,031 1,679 3,182 5,444 Warranty usage(1) (1,236 ) (1,356 ) (4,075 ) (4,016 ) Balance at end of period $ 6,876 $ 7,925 $ 6,876 $ 7,925 (1) Warranty usage includes costs incurred for warranty obligations.

Industry Segment, Geographic 24

Industry Segment, Geographic Information and Significant Customers (Tables)	9 Months Ended
	Sep. 26, 2015
Segment Reporting [Abstract]
Segment Information about Revenue, Cost of Revenue, Gross Margin and Income before Income Taxes	The table below presents segment information about revenue, cost of revenue, gross margin and income before income taxes: Three Months Ended Nine Months Ended (In thousands) September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Revenue: Home Robots $ 136,513 $ 132,013 $ 384,422 $ 373,283 Defense & Security 6,184 10,667 24,500 21,369 Other (1) 912 817 1,436 2,852 Total revenue 143,609 143,497 410,358 397,504 Cost of revenue: Home Robots 64,512 65,135 185,677 186,991 Defense & Security 3,533 4,977 14,700 11,725 Other (2) 5,706 5,496 16,382 17,068 Total cost of revenue 73,751 75,608 216,759 215,784 Gross margin: Home Robots 72,001 66,878 198,745 186,292 Defense & Security 2,651 5,690 9,800 9,644 Other (4,794 ) (4,679 ) (14,946 ) (14,216 ) Total gross margin 69,858 67,889 193,599 181,720 Research and development 18,122 17,343 55,886 51,522 Selling and marketing 19,379 15,844 60,896 53,911 General and administrative 13,701 12,008 39,195 35,938 Other expense, net (93 ) (374 ) (948 ) (469 ) Income before income taxes $ 18,563 $ 22,320 $ 36,674 $ 39,880 (1) Other revenue results from other smaller business units that do not meet the criteria of a reportable segment. (2) Other cost of revenue results from other smaller business units that do not meet the criteria of a reportable segment, as well as other operational costs not directly attributable to the home robots or defense and security reportable segments.

Goodwill, Other Intangible As25

Goodwill, Other Intangible Assets and Other Assets (Tables)	9 Months Ended
	Sep. 26, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Other Intangible Assets	Intangible assets at September 26, 2015 and December 27, 2014 consisted of the following: September 26, 2015 December 27, 2014 Cost Accumulated Amortization Net Cost Accumulated Amortization Impairment Loss Net (In thousands) Completed technology $ 26,900 $ 10,371 $ 16,529 $ 30,600 $ 9,691 1,788 $ 19,121 Research contracts — — — 100 100 — — Tradename 100 100 — 800 775 — 25 Total $ 27,000 $ 10,471 $ 16,529 $ 31,500 $ 10,566 $ 1,788 $ 19,146
Estimated Future Amortization Expense Related to Current Intangible Assets	The estimated future amortization expense is expected to be as follows: (In thousands) Remainder of 2015 $ 864 2016 3,457 2017 3,457 2018 3,457 2019 2,818 Thereafter 2,476 Total $ 16,529

Summary of Significant Accoun26

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		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]
Net income	$ 12,793	$ 14,607	$ 24,799	$ 28,417
Weighted-average shares outstanding	29,654	29,595	29,697	29,439
Dilutive effect of employee stock options and restricted shares	463	588	556	730
Diluted weighted-average shares outstanding	30,117	30,183	30,253	30,169
Basic income per share	$ 0.43	$ 0.49	$ 0.84	$ 0.97
Diluted income per share	$ 0.42	$ 0.48	$ 0.82	$ 0.94
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	700	400	500	200

Summary of Significant Accoun27

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Disclosure Summary Of Significant Accounting Policies Additional Information [Abstract]
Finite-Lived Intangible Assets, Gross	$ 27,000	$ 31,500
Finite-Lived Intangible Assets, Net	$ 16,529	$ 19,146

Summary of Significant Accoun28

Summary of Significant Accounting Policies - Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Tax provision	$ 5,770	$ 7,713	$ 11,875	$ 11,463
Effective income tax rate	31.10%	34.60%	32.40%	28.70%
Valuation Allowances and Reserves, Adjustments				$ 2,100

Summary of Significant Accoun29

Summary of Significant Accounting Policies - Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands		Sep. 26, 2015	Dec. 27, 2014
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		$ 108,100	$ 109,843
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		108,100	109,843
Fair Value, Inputs, Level 1 [Member] | Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	[1]	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		35,791	36,166
Liabilities, Fair Value Disclosure, Recurring		16
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		0	0
Fair Value, Inputs, Level 2 [Member] | Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	[1]	35,791	36,166
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		0	0
Liabilities, Fair Value Disclosure, Recurring		0
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		0	0
Fair Value, Inputs, Level 3 [Member] | Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	[1]	0	$ 0
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring	[2]	0
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring	[2]	16
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Recurring	[2]	$ 0
[1]	(1)The bond investments are valued based on observable market values as of the Company’s reporting date. The bond investments are recorded at fair value and marked-to-market at the end of each reporting period. The realized and unrealized gains and losses are included in comprehensive income for that period.
[2]	(2)Derivative instruments are valued using an income approach based on the present value of the forward rate less the contract rate multiplied by the notional amount.

Summary of Significant Accoun30

Summary of Significant Accounting Policies - Fair Value Assets Measured on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 48,751	$ 48,751
Finite-Lived Intangible Assets, Gross	27,000	31,500
Finite-Lived Intangible Assets, Net	$ 16,529	$ 19,146

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Inventory Disclosure [Abstract]
Inventory, Raw Materials, Net of Reserves	$ 7,780	$ 9,455
Inventory, Finished Goods, Net of Reserves	50,885	38,402
Inventory	$ 58,665	$ 47,857

Stock Option Plans - Additional

Stock Option Plans - Additional Information (Detail) - $ / shares	May. 20, 2015	Sep. 26, 2015	Sep. 26, 2015	Sep. 04, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Effective date for stock options plan	May 20, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		77,725
Share Price				$ 29.60
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for options			1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for options			3 years
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum period for expiration of options in case of employee termination			60 days
Maximum period for expiration of options in case of employee termination			90 days
Employee Stock Option [Member] | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for options			1 year
Minimum expiration period for options			5 years
Employee Stock Option [Member] | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for options			5 years
Minimum expiration period for options			10 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted		216,478
Two Thousand Fifteen Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance in different forms	3,100,000
Share based compensation arrangement shares available for grant		2,551,119	2,551,119

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Accounts Payable, Current [Abstract]
Accrued warranty	$ 6,876	$ 7,769
Accrued Sales Tax	557	867
Accrued rent	677	701
Accrued direct fulfillment costs	781	1,346
Accrued customer deposits	769	702
Accrued sales commissions	304	531
Accrued accounting fees	434	167
Accrued other	3,354	6,618
Accrued expenses	13,752	18,701
Accrued Bonuses, Current	4,714	8,455
Accrued compensation	11,153	16,235
Accrued Salaries	$ 6,439	$ 7,780

Derivative Instruments (Details

Derivative Instruments (Details) - Foreign Exchange Forward [Member] - Other Expense [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	$ 191
Derivative Instruments Not Designated as Hedging Instruments, Loss		$ 0	$ (1)	$ 0

Derivative Instruments Schedu35

Derivative Instruments Schedule of Derivative Instruments (Details) - Accounts Payable and Accrued Liabilities [Member] - Foreign Exchange Forward [Member] - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Derivative [Line Items]
Derivative, Notional Amount	$ 3,417	$ 0
Derivative, Fair Value, Net	$ 16	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	Sep. 26, 2015USD ($)
Outstanding POs [Abstract]
Contractual Obligation	$ 109

Commitments and Contingencies37

Commitments and Contingencies - Summary of Future Minimum Rental Payments under Operating Leases (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Commitments and Contingencies Disclosure [Abstract]
Rental expense under operating leases	$ 1,200	$ 1,200	$ 3,600	$ 3,600
Disclosure Summary Of Future Minimum Rental Payments Under Operating Leases [Abstract]
Remainder of 2015	942		942
2,016	3,873		3,873
2,017	3,427		3,427
2,018	2,959		2,959
2,019	2,925		2,925
Thereafter	978		978
Total minimum lease payments	$ 15,104		$ 15,104

Commitments and Contingencies38

Commitments and Contingencies - Activity Related to Warranty Accrual (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period		$ 7,081	$ 7,602	$ 7,769	$ 6,497
Provision		1,031	1,679	3,182	5,444
Warranty usage	[1]	(1,236)	(1,356)	(4,075)	(4,016)
Balance at end of period		$ 6,876	$ 7,925	$ 6,876	$ 7,925
[1]	Warranty usage includes costs incurred for warranty obligations.

Industry Segment, Geographic 39

Industry Segment, Geographic Information and Significant Customers - Segment Information about Revenue, Cost of Revenue, Gross Margin and Income before Income Taxes (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue		$ 143,609	$ 143,497	$ 410,358	$ 397,504
Cost of revenue	[1]	73,751	75,608	216,759	215,784
Gross margin		69,858	67,889	193,599	181,720
Research and development	[1]	18,122	17,343	55,886	51,522
Selling and marketing	[1]	19,379	15,844	60,896	53,911
General and administrative	[1]	13,701	12,008	39,195	35,938
Other expense, net		(93)	(374)	(948)	(469)
Income before income taxes		18,563	22,320	36,674	39,880
Home Robots
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue		136,513	132,013	384,422	373,283
Cost of revenue		64,512	65,135	185,677	186,991
Gross margin		72,001	66,878	198,745	186,292
Defense & Security
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue		6,184	10,667	24,500	21,369
Cost of revenue		3,533	4,977	14,700	11,725
Gross margin		2,651	5,690	9,800	9,644
Other (1)
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	[2]	912	817	1,436	2,852
Cost of revenue	[3]	5,706	5,496	16,382	17,068
Gross margin		$ (4,794)	$ (4,679)	$ (14,946)	$ (14,216)
[1]	Total stock-based compensation recorded in the three and nine months ended September 26, 2015 and September 27, 2014 included in the above figures breaks down by expense classification as follows: Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014Cost of revenue$270 $291 $662 $626Research and development963 866 2,737 2,425Selling and marketing474 319 1,089 860General and administrative2,193 2,315 5,974 6,105
[2]	(1)Other revenue results from other smaller business units that do not meet the criteria of a reportable segment.
[3]	(2)Other cost of revenue results from other smaller business units that do not meet the criteria of a reportable segment, as well as other operational costs not directly attributable to the home robots or defense and security reportable segments.

Industry Segment, Geographic 40

Industry Segment, Geographic Information and Significant Customers - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015customerSegment	Sep. 27, 2014customer
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments			2
Number of customer generating major revenues | customer			2	2
Customer Concentration Risk [Member] | Customer Concentration Risk [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration Risk, Percentage	55.90%	63.40%	60.30%	64.20%
Customer Concentration Risk [Member] | International distributors of home robots products | Distributor One
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration Risk, Percentage	11.40%	17.50%	12.90%	19.10%
Customer Concentration Risk [Member] | International distributors of home robots products | Distributor Two
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration Risk, Percentage	16.50%	14.00%	14.90%	13.20%
Customer Concentration Risk [Member] | Customer Concentration Risk [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration Risk, Percentage	10.20%

Goodwill, Other Intangible As41

Goodwill, Other Intangible Assets and Other Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 27, 2014
Business Acquisition [Line Items]
Goodwill	$ 48,751		$ 48,751		$ 48,751
Amortization of Acquired Intangible Assets	900	$ 900	$ 2,600	$ 2,700
Minimum
Business Acquisition [Line Items]
Estimated useful life of intangible assets			3 years
Maximum
Business Acquisition [Line Items]
Estimated useful life of intangible assets			10 years
Home Robots | Evolution Robotics, Inc. (ER)
Business Acquisition [Line Items]
Goodwill	41,100		$ 41,100
Defense & Security | Nekton Research LLC [Member]
Business Acquisition [Line Items]
Goodwill	$ 7,700		$ 7,700

Goodwill, Other Intangible As42

Goodwill, Other Intangible Assets and Other Assets - Other Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 27, 2014
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 27,000		$ 27,000		$ 31,500
Intangible assets accumulated amortization	10,471		10,471		10,566
Finite-lived intangible assets, accumulated impairment loss					1,788
Intangible Assets, Net	16,529		16,529		19,146
Amortization of Acquired Intangible Assets	900	$ 900	2,600	$ 2,700
Completed technology
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	26,900		26,900		30,600
Intangible assets accumulated amortization	10,371		10,371		9,691
Finite-lived intangible assets, accumulated impairment loss					1,788
Intangible Assets, Net	16,529		16,529		19,121
Research contracts
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	0		0		100
Intangible assets accumulated amortization	0		0		100
Finite-lived intangible assets, accumulated impairment loss					0
Intangible Assets, Net	0		0		0
Trade Names
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	100		100		800
Intangible assets accumulated amortization	100		100		775
Finite-lived intangible assets, accumulated impairment loss					0
Intangible Assets, Net	$ 0		$ 0		$ 25

Goodwill, Other Intangible As43

Goodwill, Other Intangible Assets and Other Assets - Estimated Future Amortization Expense Related to Current Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Disclosure Estimated Future Amortization Expense Related To Current Intangible Assets [Abstract]
Remainder of 2015	$ 864
2,016	3,457
2,017	3,457
2,018	3,457
2,019	2,818
Thereafter	2,476
Intangible Assets, Net	$ 16,529	$ 19,146

Subsequent Event (Details)

Subsequent Event (Details) - Subsequent Event [Member] - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Jan. 02, 2016	Jan. 02, 2016
Subsequent Event [Line Items]
Proceeds from Sale of Other Investments		$ 5.6
Cost-method Investments, Realized Gains	$ 3
Estimated impact of subsequent event on EPS		$ 0.06