AtriCure (ATRC) 10-Q 29 Apr 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 27, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Trading Symbol	ATRC
Entity Registrant Name	AtriCure, Inc.
Entity Central Index Key	1,323,885
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		33,094,148

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 20,768	$ 23,764
Short-term investments	2,556	10,814
Accounts receivable, less allowance for doubtful accounts of $129 and $136, respectively	19,446	19,409
Inventories	19,015	17,659
Other current assets	3,608	3,106
Total current assets	65,393	74,752
Property and equipment, net	31,155	31,279
Long-term investments	6,150	7,706
Intangible assets, net	53,364	53,775
Goodwill	105,257	105,257
Other noncurrent assets	391	323
Total Assets	261,710	273,092
Current liabilities:
Accounts payable	12,801	12,744
Accrued liabilities	12,931	18,394
Other current liabilities and current maturities of capital leases	462	450
Total current liabilities	26,194	31,588
Capital leases	13,592	13,710
Other noncurrent liabilities	40,897	41,109
Total Liabilities	$ 80,683	$ 86,407
Commitments and contingencies (Note 7)
Stockholders' Equity:
Common stock, $0.001 par value, 90,000 shares authorized and 33,084 and 32,274 issued and outstanding, respectively	$ 33	$ 32
Additional paid-in capital	356,638	352,900
Accumulated other comprehensive loss	(284)	(611)
Accumulated deficit	(175,360)	(165,636)
Total Stockholders' Equity	181,027	186,685
Total Liabilities and Stockholders' Equity	$ 261,710	$ 273,092

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 129	$ 136
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	33,084,000	32,274,000
Common stock, shares outstanding	33,084,000	32,274,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Consolidated Statements of Operations and Comprehensive Loss [Abstract]
Revenue	$ 35,940	$ 29,886
Cost of revenue	10,026	8,151
Gross profit	25,914	21,735
Operating expenses:
Research and development expenses	8,563	5,609
Selling, general and administrative expenses	26,770	21,270
Total operating expenses	35,333	26,879
Loss from operations	(9,419)	(5,144)
Other income (expense):
Interest expense	(259)	(18)
Interest income	39	43
Other	(80)	(141)
Loss before income tax expense	(9,719)	(5,260)
Income tax expense	5	6
Net loss	$ (9,724)	$ (5,266)
Basic and diluted net loss per share	$ (0.31)	$ (0.19)
Weighted average shares outstanding-basic and diluted	31,358	27,069
Comprehensive loss:
Unrealized gains on investments	$ 41	$ 37
Foreign currency translation adjustment	286	(487)
Other comprehensive income (loss)	327	(450)
Net loss	(9,724)	(5,266)
Comprehensive loss	$ (9,397)	$ (5,716)

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (9,724)	$ (5,266)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	2,842	1,724
Depreciation	1,800	1,008
Amortization of intangible assets	411	303
Amortization of deferred financing costs	15	16
Loss on disposal of property and equipment	141	57
Realized (gain) loss from foreign exchange on intercompany transactions	(5)	251
Amortization/accretion on investments	56	184
Change in allowance for doubtful accounts		100
Changes in operating assets and liabilities:
Accounts receivable	30	(2,685)
Inventories	(1,232)	(1,104)
Other current assets	(439)	(779)
Accounts payable	1,034	2,124
Accrued liabilities	(5,569)	(4,931)
Other noncurrent assets and liabilities	(291)	28
Net cash used in operating activities	(10,931)	(8,970)
Cash flows from investing activities:
Purchases of available-for-sale securities		(6,086)
Sales and maturities of available-for-sale securities	9,800	11,899
Purchases of property and equipment	(2,804)	(1,434)
Increases in property under build-to-suit obligation		(1,822)
Net cash provided by investing activities	6,996	2,557
Cash flows from financing activities:
Payments on capital leases	(107)	(14)
Increases in build-to-suit obligation		1,822
Proceeds from stock option exercises	1,896	516
Shares repurchased for payment of taxes on stock awards	(999)	(503)
Net cash provided by financing activities	790	1,821
Effect of exchange rate changes on cash and cash equivalents	149	(233)
Net decrease in cash and cash equivalents	(2,996)	(4,825)
Cash and cash equivalents-beginning of period	23,764	28,384
Cash and cash equivalents-end of period	20,768	23,559
Supplemental cash flow information:
Cash paid for interest	244	2
Non-cash investing and financing activities:
Accrued purchases of property and equipment	$ 243	751
Assets acquired through capital lease		$ 36

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2016
Description of Business and Summary of Significant Accounting Policies [Abstract]
Description of Business and Summary of Significant Accounting Policies	1. DESC RIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of the Business —AtriCure, Inc. was incorporated in the State of Delaware on October 31, 2000. The “Company” or “AtriCure” consists of AtriCure, Inc. and its wholly-owned subsidiaries. The Company is a leading atrial fibrillation (Afib) solutions partner providing innovative products, professional education and support for clinical science to reduce the economic and social burden of atrial fibrillation. The Company sells its products to medical centers globally through a direct sales force and distributors. Basis of Presentation —The accompanying interim financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (SEC). The accompanying interim financial statements are unaudited, but in the opinion of the Company’s management, contain all of the normal, recurring adjustments considered necessary to present fairly the financial position, results of operations and cash flows for the periods presented in conformity with accounting principles generally accepted in the United States of America (GAAP) applicable to interim periods. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been omitted or condensed. The Company believes the disclosures herein are adequate to make the information presented not misleading. Results of operations are not necessarily indicative of the results expected for the full fiscal year or for any future period. The accompanying Condensed Consolidated Financial Statements should be read in conjunction with the audited financial statements of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 filed with the SEC. Principles of Consolidation —The Condensed Consolidated Financial Statements include the accounts of the Company, AtriCure, LLC, Endoscopic Technologies, LLC and nContact Surgical, LLC, the Company’s wholly-owned subsidiar ies, all organized in the State of Delaware, and AtriCure Europe B.V. (AtriCure Europe), the Company’s wholly-owned subsidiary incorporated in the Netherlands. All intercompany accounts and transactions have been eliminated in consolidation. Cash and Cash Equivalents —The Company considers highly liquid investments with maturities of three months or less at the date of acquisition as cash equivalents in the accompanying Condensed Consolidated Financial Statements. Investments —The Company places its investments primarily in U.S. Government agencies and securities, corporate bonds and commercial paper. The Company classifies all investments as available-for-sale. Investments with maturities of less than one year are classified as short-term investments. Investments are recorded at fair value, with unrealized gains and losses recorded as accumulated other comprehensive income (loss). The Company recognizes gains and losses when these securities are sold using the specific identification method and includes them in interest income or expense in the Condensed Consolidated Statements of Operations and Comprehensive Loss. Revenue Recognition —The Company accounts for revenue in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 605, “Revenue Recognition” (ASC 605). The Company recognizes revenue when all of the following criteria are met: (i) there is persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured. Pursuant to the Company’s standard terms of sale, revenue is recognized when title to the goods and risk of loss transfers to customers and there are no remaining obligations that will affect the customers’ final acceptance of the sale. Generally, the Company’s standard terms of sale define the transfer of title and risk of loss to occur upon shipment to the respective customer. The Company generally does not maintain any post-shipping obligations to the recipients of the products. No installation, calibration or testing of products is performed by the Company subsequent to shipment to the customer in order to render it operational. Revenue includes shipping and handling revenue of $296 and $247 for the three months ended March 31, 2016 and 2015 , respectively. Cost of freight for shipments made to customers is included in cost of revenue. Sales and other value-added taxes collected from customers and remitted to governmental authorities are excluded from revenue. The Company sells its products primarily through a direct sales force, with certain international markets sold through distributors. Terms of sale are generally consistent for both end-users and distributors except that payment terms are generally net 30 days for end-users and net 60 days for distributors with limited exceptions. Sales Returns and Allowances —The Company maintains a provision for sales returns and allowances to account for potential returns of defective or damaged products, products shipped in error and invoice adjustments. The Company estimates such provision on a quarterly basis based primarily on specific identification, in addition to estimating a general reserve based on historical experience. Increases to the provision result in a reduction of revenue. The provision is included in accrued liabilities in the Condensed Consolidated Balance Sheets. Allowance for Doubtful Accounts Receivable —The Company evaluates the collectability of accounts receivable to determine the appropriate reserve for doubtful accounts. In determining the amount of the reserve, the Company considers aging of account balances, historical credit losses, customer-specific information and other relevant factors. An increase to the allowance for doubtful accounts results in a corresponding increase in selling, general and administrative expense. The Company reviews accounts receivable and adjusts the allowance based on current circumstances and charges off uncollectible receivables against the allowance when all attempts to collect the receivable have failed. The Company’s history of write-offs against the allowance has not been significant. Inventories —Inventories are stated at the lower of cost or market using approximate costs based on the first-in, first-out cost method (FIFO) . Inventories consist of raw materials, work in process and finished goods. The Company’s industry is characterized by rapid product development and frequent new product introductions. Uncertain timing of product approvals, variability in product launch strategies and variation in product utilization all impact excess and obsolete inventory. An inventory allowance based on product usage is estimated and recorded quarterly for excess, slow moving and obsolete inventory, as well as inventory with a carrying value in excess of its net realizable value. An increase to the inventory reserve allowance results in a corresponding increase in cost of revenue. Write-offs are recorded when a product is destroyed. The Company’s history of write-offs against the reserve has not been significant. Inventories consist of the following:      March 31, December 31,  2016 2015  Raw materials $ 6,228 $ 6,159  Work in process 2,023 974  Finished goods 10,764 10,526  Inventories $ 19,015 $ 17,659 Property and Equipment —Property and equipment is stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method of depreciation for financial reporting purposes and is applied over the estimated useful lives of the assets. The estimated useful life by major asset category is the following: generators and other capital equipment, machinery, equipment and vehicles is three to seven years, computer and other office equipment is three years, furniture and fixtures is three to seven years and leasehold improvements and equipment under capital leases are the shorter of their useful life or remaining lease term. The Company reassesses the useful lives of property and equipment annually, and assets are retired if they are no longer in service. Maintenance and repair costs are expensed as incurred. Generators and other capital equipment (such as the Company’s switchbox units and cryosurgical consoles) are placed with direct customers that use the Company’s disposable products. Depreciation of such assets is included in cost of revenue. The estimated useful lives of this equipment are based on anticipated usage by customers and the timing and impact of expected new technology rollouts by the Company. To the extent the Company experiences changes in the usage of this equipment or introduces new technologies, the estimated useful lives of this equipment may change in a future period. Depreciation related to these generators was $836 and $620 for the three months ended March 31, 2016 and 2015 , respectively. As of March 31, 2016 and December 31, 2015 , the net carrying amount of loaned equipment included in net property and equipment in the Condensed Consolidated Balance Sheets was $5,393 and $5,447 , respectively. The Company reviews property and equipment for impairment using its best estimates based on reasonable and supportable assumptions and projections. Intangible Assets —Intangible assets with determinable useful lives are amortized on a straight-line basis over the estimated periods benefited. Included in intangible assets is In Process Research and Development (IPR&D). The Company defines IPR&D as the value of acquired technology which has not yet reached technological feasibility. The primary basis for determining the technological feasibility is obtaining specific regulatory approvals. The estimated fair value of IPR&D acquired in a business combination is capitalized as an indefinite-lived intangible asset until completion or abandonment of the IPR&D project. Upon completion of the development project, the IPR&D is amortized over its estimated useful life. If the IPR&D project is abandoned, the related IPR&D asset is written off. The estimated fair value of IPR&D was determined using an income approach model. IPR&D represents an estimate of the fair value of the PMA approval that could result from the CONVERGE IDE clinical trial. The Company reviews intangible assets for impairment using its best estimates based on reasonable and supportable assumptions and projections. Goodwill— Goodwill represents the excess of purchase price over the fair value of the net assets acquired in business combinations. The Company tests goodwill for impairment annually on November 30, or more often if impairment indicators are present. The Company’s goodwill is accounted for in a single reporting unit representing the Company as a whole. Other Current Liabilities and Current Maturities of Capital Leases— As of March 31, 201 6 , o ther current liabilities consisted of a financing obligation related to the construction of the Company’s new headquarters. Current maturities of capital leases consist of capital lease obligations with maturities of less than one year (see Note 6 – Indebtedness). Other Noncurrent Liabilities— Other noncurrent liabilities include contingent consideration recorded in business combinations, as well as long-term deferred revenues and other contractual obligations. Other Income — Other income consists primarily of foreign currency transaction gains and losses. The Company recorded net foreign currency transaction gains (losses) of $(80) and $(163) for the three months ended March 31, 2016 and 2015 , respectively, in connection with settlements of its intercompany balance with AtriCure Europe and invoices transacted in British Pounds. Taxes —Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rates is recognized in the period that includes the enactment date. The Company’s estimate of the valuation allowance for deferred tax assets requires it to make significant estimates and judgments about its future operating results. Deferred tax assets are reduced by valuation allowances if, based on the consideration of all available evidence, it is more-likely-than-not that some portion of the deferred tax asset will not be realized. Significant weight is given to evidence that can be objectively verified. The Company evaluates deferred tax assets on a quarterly basis to determine if valuation allowances are required by considering all available evidence. Deferred tax assets are realized by having sufficient future taxable income to allow the related tax benefits to reduce taxes otherwise payable. The sources of taxable income that may be available to realize the benefit of deferred tax assets are future reversals of existing taxable temporary differences, future taxable income, exclusive of reversing temporary differences and carryforwards, taxable income in carry-back years and tax planning strategies that are both prudent and feasible. In evaluating whether to record a valuation allowance, the applicable accounting standards deem that the existence of cumulative losses in recent years is a significant piece of objectively verifiable negative evidence that must be overcome by objectively verifiable positive evidence to avoid the need to record a valuation allowance. The Company has recorded a full valuation allowance against its net deferred tax assets as it is more likely than not that the benefit of the deferred tax assets will not be recognized in future periods. A provision of The Patient Protection and Affordable Care Act enacted in 2010, as amended (Patient Act), requires manufacturers of medical devices to pay an excise tax on all U.S. medical device sales. In December 2015, the U.S. gove rnment approved the suspension of the excise tax on medical device sales beginning January 1, 2016 through December 31, 2017. The Company’s expense related to the medical device excise tax, which was recorded in cost of revenue, was $0 and $155 for the three months ended March 31, 2016 and 2015 , respectively. Net Loss Per Share —Basic and diluted net loss per share is computed in accordance with FASB ASC 260, “Earnings Per Share” (ASC 260) by dividing the net loss by the weighted average number of common shares outstanding during the period. Since the Company has experienced net losses for all periods presented, net loss per share excludes the effect of 4,480 and 4,320 stock options and restricted stock shares as of March 31, 2016 and 2015 , respectively, because they are anti-dilutive. Therefore the number of shares calculated for basic net loss per share is also used for the diluted net loss per share calculation. Comprehensive Loss and Accumulated Other Comprehensive Loss —In addition to net losses, the comprehensive loss includes foreign currency translation adjustments and unrealized gains and losses on investments. Accumulated other comprehensive income (loss) consisted of the following:      Three Months Ended  March 31,  2016 2015  Total accumulated other comprehensive loss at beginning of period $ (611) $ (348)  Unrealized Gains on Investments  Balance at beginning of period $ (39) $ (54)  Other comprehensive income (loss) before reclassifications 41 37  Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations — —  Balance at end of period $ 2 $ (17)  Foreign Currency Translation Adjustment  Balance at beginning of period $ (572) $ (294)  Other comprehensive income (loss) before reclassifications 281 (324)  Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations 5 (163)  Balance at end of period $ (286) $ (781)  Total accumulated other comprehensive loss at end of period $ (284) $ (798) Research and Development —Research and development costs are expensed as incurred. These costs include compensation and other internal and external costs associated with the development and research related to new and existing products or concepts, preclinical studies, clinical trials, healthcare compliance and regulatory affairs. Advertising Costs — The Company expenses advertising costs as incurred. Advertising costs were not significant during the three months ended March 31, 2016 and 2015 . Share-Based Compensation —The Company follows FASB ASC 718, “Compensation-Stock Compensation” (ASC 718) to record share-based compensation for all employee share-based payment awards, including stock options, restricted stock and stock purchases related to an employee stock purchase plan, based on estimated fair values. The Company’s share-based compensation expense recognized under ASC 718 for the three months ended March 31, 2016 and 2015 was $2,842 and $1,724 , respectively, on a before and after tax basis. ASC 718 requires companies to estimate the fair value of share-based payment awards on the date of grant using an option-pricing model. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in the Company’s Condensed Consolidated Statement of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures. ASC 718 requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The Company estimates the fair value of time-based options on the date of grant using the Black-Scholes option-pricing model (Black-Scholes model). The Company’s determination of fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price, as well as assumptions regarding a number of subjective variables. These variables include but are not limited to the Company’s expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors. The fair value of market-based performance option grants is estimated at the date of grant using a Monte-Carlo simulation. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in the Consolidated Statement of Operations and Comprehensive Loss. The Company estimates the fair value of restricted stock based upon the grant date closing market price of the Company’s common stock. The Company’s determination of fair value is affected by the Company’s stock price as well as assumptions regarding the number of shares expected to be granted. The Company also has an employee stock purchase plan (ESPP) which is available to all eligible employees as defined by the plan document. Under the ESPP, shares of the Company’s common stock may be purchased at a discount. The Company estimates the number of shares to be purchased under the ESPP and records compensation expense based upon the fair value of the stock at the beginning of the purchase period using the Black-Scholes model. Use of Estimates —The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reporting period. Actual results could differ from those estimates. Fair Value Disclosures —The Company classifies and records cash and investments in U.S. government agencies and securities as Level 1 within the fair value hierarchy. Accounts receivable, short-term other assets, accounts payable and accrued liabilities are also classified as Level 1. The carrying amounts of these assets and liabilities approximate their fair value due to their relatively short-term nature. Cash equivalents and investments in corporate bonds are classified as Level 2 within the fair value hierarchy (see Note 3 – Fair Value for further information). Significant unobservable inputs with respect to the fair value measurement of the Level 3 contingent consideration liabilit y is developed using Company data. When an input is changed, the corresponding valuation models are updated and the results are analyzed for reasonableness.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2016
Recent Accounting Pronouncements [Abstract]
Recent Accounting Pronouncements	2. RECENT ACCOUNTING PRONOUNCEMENTS In May 2014 the FASB issued a final standard on revenue from contracts with customers. The standard, issued as FASB ASU 2014-09, “ Revenue from Contracts with Customers” (ASU 2014-09), outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. In July 2015 the FASB decided to defer the effective date of ASU 2014-09 for entities reporting under U.S. GAAP from interim and annual reporting periods beginning after December 15, 2016 to interim and annual reporting periods beginning after December 15, 2017 and allow early adoption as of the original effective date. A full retrospective or modified retrospective approach may be taken to adopt the guidance in the ASU. The Company is evaluating the impact of the provisions of ASU 2014-09 on its consolidated financial position, results of operations and related disclosures. In November 2015 the FASB issued ASU 2015-17, “Income Taxes (Topic 740), Balance Sheet Classification of Deferred Taxes” (ASU 2015-17), which requires companies to classify all deferred tax assets and liabilities as noncurrent on the balance sheet instead of separating deferred taxes into current and noncurrent amounts. Also, companies will no longer allocate valuation allowances between current and noncurrent deferred tax assets because those allowances also will be classified as noncurrent. ASU 2015-17 is effective for financial statements issued for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted for financial statements that have not been issued. The Company has evaluat ed the impact of the provisions of ASU 2015-17 on its consolidated financial position and related disclosures and has determined that the new guidance does not have a material impact on its financial reporting . In January 2016 the FASB issued ASU 2016-01, “Financial Instruments — Overall — Recognition and Measurement of Financial Assets and Financial Liabilities” (ASU 2016-01), which amends the guidance in U.S. GAAP on the classification and measurement of financial instruments. Although the ASU retains many current requirements, it significantly revises an entity’s accounting related to (1) the classification and measurement of investments in equity securities and (2) the presentation of certain fair value changes for financial liabilities measured at fair value. The ASU also amends certain disclosure requirements associated with the fair value of financial instruments. The new standard is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2017. The Company is evaluating the impact of ASU 2016-01 on its consolidated financial position and related disclosures. In February 2016 the FASB issued ASU 2016-02, “Leases” (ASU 2016-02) which requires lessees to record most leases on to their balance shee t but recognize expenses on their income statement in a manner similar to today’s accounting. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. Full retrospective application is prohibited. The Company is evaluating the provisions of ASU 2016-02 to determine the impact on its consolidated financial position and related disclosures. In March 2016 the FASB issued ASU 201 6 - 09 , “ Improvements to Employee Share-Based Payment Accounting ” (ASU 201 6 - 09 ), which changes certain aspects of accounting for share-based payments to employees . The new guidance requires all income tax effects of awards to be recognized in the income statement when the awards vest or are settled. It also allows an employer to repurchase more of an employee’s shares for tax withholding purposes without triggering liability accounting and to make a policy election to account for forfeitures as they occur. ASU 201 6-09 i s effective for fiscal years beginning after December 15, 2016, and interim periods within those years . Early adoption is permitted, but all of the guidance within the ASU must be adopted in the same period. The Company is evaluating the impact of ASU 2016-09 on its consolidated financial position, results of operations and related disclosures .

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2016
Fair Value [Abstract]
Fair Value	3. FAIR VALUE FASB ASC 820, “Fair Value Measurements and Disclosures” (ASC 820) defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The standard describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value which are the following: · Level 1—Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. An active market for the asset or liability is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. The valuation under this approach does not entail a significant degree of judgment. · Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The valuation technique for the Company’s Level 2 assets is based on quoted market prices for similar assets from observable pricing sources at the reporting date. · Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Unobservable inputs shall be used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. The fair value of the Company’s Level 3 contingent consideration liability was estimated on the acquisition date of nContact Surgical, Inc. (nContact) and i s revalued at the end of each subsequent reporting period. In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2016 :      Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Total  Assets:  Money market funds $ — $ 13,041 $ — $ 13,041  U.S. government agencies and securities 1,580 — — 1,580  Corporate bonds — 7,125 — 7,125  Total assets $ 1,580 $ 20,166 $ — $ 21,746  Liabilities:  Acquisition-related contingent consideration — — 40,207 40,207  Total liabilities $ — $ — $ 40,207 $ 40,207 There were no changes in the levels or methodology of measurement of financial assets and liabilities during the three month period ended March 31, 2016 . In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2015 :      Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Total  Assets:  Money market funds $ — $ 18,572 $ — $ 18,572  U.S. government agencies and securities 1,590 — — 1,590  Corporate bonds — 16,930 — 16,930  Total assets $ 1,590 $ 35,502 $ — $ 37,092  Liabilities:  Acquisition-related contingent consideration — — 40,207 40,207  Total liabilities $ — $ — $ 40,207 $ 40,207  There were no changes in the levels or methodology of measurement of financial assets and liabilities during the twelve months ended December 31, 2015 . Acquisition-Re lated Contingent Consideration. Contingent consideration arrangements obligate the Company to pay former shareholders of an acquired entity if specified future events occur or conditions are met, such as the achievement of certain technological milestones or the achievement of targeted revenue milestones. The Company measures such liabilities using unobservable inputs, applying the income approach, such as the discounted cash flow technique or the probability-weighted scenario method. Various key assumptions, such as the probability of achievement of the agreed milestones, projected revenues from acquisitions and the discount rate, are used in the determination of fair value of contingent consideration arrangements and are not observable in the market, thus representing a Level 3 measurement within the fair value hierarchy. Subsequent revisions to key assumptions, which impact the estimated fair value of contingent consideration liabilities, are reflected in the Condensed Consolidated Statements of Operations and Comprehensive Loss. The Company acquired nContact on October 13, 2015. The aggregate consideration paid to nContact shareholders includes up to $50,000 in contingent consideration based on completion of enrollment of the CONVERGE IDE trial and corresponding PMA approval by December 31, 2020. nContact shareholders are entitled to additional contingent consideration based on revenue in excess of an annual growth rate of more than 25% through 2019. There were no changes in the estimates, discount rate or measurement period during the three months ended March 31, 2016. The following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for acquisition-related contingent consideration as of March 31, 2016:    Beginning Balance – January 1, 2016 $ 40,207  Amounts acquired —  Transfers in (out) of Level 3 —  Changes in fair value included in earnings —  Ending Balance – March 31, 2016 $ 40,207 The following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for acquisition-related contingent consideration as of December 31, 2015 :      Beginning Balance – January 1, 2015 $ —  Amounts acquired 40,207  Transfers in (out) of Level 3 —  Changes in fair value included in earnings —  Ending Balance – December 31, 2015 $ 40,207

Intangible Assets

Intangible Assets	3 Months Ended
	Mar. 31, 2016
Intangible Assets [Abstract]
Intangible Assets	4. INTANGIBLE ASSETS The following table provides a summary of the Company’s intangible assets:      March 31, December 31,  2016 2015  Cost Accumulated Amortization Cost Accumulated Amortization   Non-compete agreement $ 100 $ 100 $ 100 $ 100  Fusion technology 9,242 2,079 9,242 1,848  Clamp & probe technology 829 622 829 552  Estech trade name 208 208 208 208  SUBTLE access technology 2,179 206 2,179 96  IPR&D 44,021 — 44,021 —  Total $ 56,579 $ 3,215 $ 56,579 $ 2,804  Amortization expense related to intangible assets with definite lives was $411 and $303 for the three months ended March 31, 2016 and 2015 , respectively. Future amortization expense related to intangible assets with definite lives is projected as follows:      2016 $ 1,233 April 1, 2016 through December 31, 2016  2017 1,367  2018 1,367  2019 1,367  2020 1,235  2021 and thereafter 2,774  Total $ 9,343

Accrued Liabilities

Accrued Liabilities	3 Months Ended
	Mar. 31, 2016
Accrued Liabilities [Abstract]
Accrued Liabilities	5. ACCRUED LIABILITIES Accrued liabilities consisted of the following:      March 31, December 31,  2016 2015  Accrued payroll and employee-related expenses $ 4,694 $ 4,021  Accrued commissions 3,045 6,061  Accrued taxes and value-added taxes payable 2,214 912  Accrued bonus 1,565 6,088  Other accrued liabilities 807 723  Accrued royalties 398 382  Sales returns allowance 208 207  Total $ 12,931 $ 18,394

Indebtedness

Indebtedness	3 Months Ended
	Mar. 31, 2016
Indebtedness [Abstract]
Indebtedness	6. INDEBTEDNESS Bank Credit Facility. The Company has a debt agreement (Loan Agreement) with Silicon Valley Bank (SVB). The Loan A greement, as amended, restated and modified, includes a $15,000 revolvi ng credit facility which matures on April 30, 2018 . Borrowing availability under the revolving credit facility is based on the lesser of $15,000 or a borrowing base calculation as defined by the Loan A greement. As of March 31, 2016 the Company had no borrowings under the revolving credit facility and had borrowing availability of $15,000 . The applicable interest rate is 3.5% . Effective April 25, 2016, the Company and SVB entered into the Second Amended and Restated Loan and Security Agreement which amends and restates the Company’s credit facility with SVB. The agreement provides for a new $25,000 term loan, in addition to a $15,000 revolving line of credit, both which mature in April 2021 . The term loan has a five -year term, with principal payments to be made ratably commencing twelve months after the inception of the loan through to the loan’s maturity date. If the Company meets certain conditions, as specified by the loan agreement, the commencement of term loan principal payments may be deferred by an additional six months. The term loan accrues interest at the Prime Rate and is subject to an additional 4.0% fee on the original $25,000 term loan principal amount at maturity. The revolving line of credit is subject to an annual commitment fee of $50 , and any borrowings bear interest at the Prime Rate. The Second Amended and Restated Loan and Security Agreement also provides for certain prepayment and early termination fees, as well as establishes covenants related to liquidity, sales growth and a minimum cash balance, along with other terms and conditions similar to those in the Company’s previous agreements with SVB. The proceeds from the agreement are expected to fund current and future operations of the Company. Capital Lease Obligations. As of March 31, 2016 the Company had capital leases for its corporate headquarters building and computer equipment that expire at various terms through 2030 . In August 2014, t he Company entered into a new building lease (Mason Lease) in order to re-locate its corporate headquarters and West Chester, Ohio facilities from their current location to a building to be constructed on Innovation Way in Mason, Ohio. The term of the Mason Lease is fifteen years with three separate five -year renewal options, at the Company’s option, and commenced in Octo ber 2015. On the Commencement Date, the Company provide d a letter of credit to the Landlord in the amount of $1,250 , which amount may decrease or be removed entirely based on the Company’s financial performance. The Company wa s deemed the owner of the project during the construction period. As a result, project costs incurred during construction of the building were included in property and equipment as construction in progress and the corresponding financing obligation wa s included in other current liabilities during the construction period . I ncrease s in purchases of building under construction and proceeds from the construction financing obligation we re also included in the Condensed Consolidated Statement of Cash Flows during the construction period . Upon completion of construction, t he Company recor ded the current and noncurrent portions of the Mason Lease obligation within capital leases and the va lue of the underlying asset in p roperty and e quipment in the Condensed Consolidated Balance Sheet . The cost of the leased assets , both building and computer equipment, under lease at March 31, 2016 was $14,462 . The assets are depreciated over their estimated useful lives, which equal the terms of the leases. Accumulated amortization on the capital leases was $597 at March 31, 2016 . Future maturities on capital lease obligations are projected as follows:      2016 $ 1,065 April 1, 2016 through December 31, 2016  2017 1,425  2018 1,439  2019 1,457  2020 1,479  2021 and thereafter 15,894  Total payments $ 22,759  Imputed interest (8,705)  Net capital lease obligations, of which $462 is current and $13,592 is noncurrent $ 14,054

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies [Abstract]
Commitments and Contingencies	7. COMMITMENTS AND CONTINGENCIES Lease Commitments . The Company leases certain office, manufacturing and warehouse facilities and equipment under noncancelable operating leases that expire at various terms through 2021 . Royalty Agreements . The Company has certain royalty agreements in place with terms that include payment of royalties based on product revenue from sales of specified current products. The royalty agreements have effective dates as early as 2003 and terms ranging from three years to at least twenty years. The royalties range from 0.75% to 5% of specified product sales. Parties to the royalty agreements have the right at any time to terminate the agreement immediately for cause. Royalty expense of $441 and $427 was recorded as part of cost of revenue for the three months ended March 31, 2016 and 2015, respectively . Purchase Agreements . The Company enters into standard purchase agreements with certain vendors in the ordinary course of business. Outstanding commitments at March 31, 2016 and 2015 were not significant. Legal . The Company is not currently party to any material pending or threatened litigation. The Company may, from time to time, become a party to legal proceedings.

Income Tax Provision

Income Tax Provision	3 Months Ended
	Mar. 31, 2016
Income Tax Provision [Abstract]
Income Tax Provision	8. INCOME TAX PROVISION The Company files federal, state, and foreign income tax returns in jurisdictions with varying statutes of limitations. Income taxes are computed using the asset and liability method in accordance with FASB ASC 740, “Income Taxes”, under which deferred income taxes are provided for the temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities. Deferred taxes are measured using provisions of currently enacted tax laws. A valuation allowance against deferred tax assets is recorded when it is more-likely-than-not that such assets will not be fully realized. The Company has recorded a full valuation allowance against its net deferred tax assets as it is more-likely-than-not that the benefit of the deferred tax assets will not be recognized in future periods. Tax credits are accounted for as a reduction of income taxes in the year in which the credit originates. The Company does not expect any significant unrecognized tax benefits to arise over the next twelve months. The Company’s provision for income taxes for continuing operations in interim periods is computed by applying its estimated annual effective rate against its loss before income tax (expense) benefit for the period. In addition, non-recurring or discrete items are recorded during the period in which they occur. The effective tax rate for the three months ended March 31, 2016 and 2015 was (0.05%) and (0.11%) , respectively. The Company has not had to accrue any interest and penalties related to unrecognized income tax benefits as a result of offsetting of net operating losses. However, if the situation occurs, the Company will recognize interest and penalties within the income tax expense (benefit) line in the Condensed Consolidated Statements of Operations and Comprehensive Loss and within the related tax liability line in the Condensed Consolidated Balance Sheets. Federal, state and local tax returns of the Company are routinely subject to review by various taxing authorities.

Equity Compensation Plans

Equity Compensation Plans	3 Months Ended
	Mar. 31, 2016
Equity Compensation Plans [Abstract]
Equity Compensation Plans	9. EQUITY COMPENSATION PLANS The Company has several share-based incentive plans: the 2005 Equity Incentive Plan (2005 Plan), the Amended and Restated 2014 Stock Incentive Plan (2014 Plan) and the 2008 Employee Stock Purchase Plan (ESPP). 2005 Plan and 2014 Plan The Company granted awards under the 2005 Plan until the 2014 Annual Meeting of Stockholders at which stockholders adopted the 2014 Plan. Pursuant to its terms, the 2014 Plan supersedes and replaces the 2005 Plan. Under the 2014 Plan, the Board of Directors may grant incentive stock options to employees and any parent or subsidiary’s employees, and may grant nonstatutory stock options, restricted stock or stock appreciation rights to employees, directors and consultants of the Company and any parent or subsidiary’s employees, directors and consultants. The administrator (currently the Compensation Committee of the Board of Directors) has the power to determine the terms of any awards, including the number of shares subject to each award, the exercisability of the awards and the form of consideration. As of March 31, 2016 , 8,949 shares of common stock had been reserved for issuance under the 2014 Plan. Options granted under the plans generally expire ten years fr om the date of grant. Options granted from the 2005 Plan and 2014 Plan generally vest at a rate of 25% on the first anniversary date of the grant and ratably each month thereafter over the following three years . Restricted stock awards granted under the 2005 Plan and 2014 Plan generally vest 25% annually over four years from date of grant. Employee Stock Purchase Plan (ESPP) T he Employee Stock Purchase Plan is available to eligible employees as defined in the ESPP. Under the ESPP, shares of the Company’s common stock may be purchased at a discount (currently 15% ) of the lesser of the closing price of the Company’s common stock on the first trading day or the last trading day of the offering period. The offering period (currently six months) and the offering price are subject to change. Participants may not purchase more than $25 of the Company’s common stock in a calendar year and, effective January 1, 2014, may not purchase a value of more than 3 shares during an offering period. Beginning on January 1, 2009 and on the first day of each fiscal year thereafter during the term of the ESPP, the number of shares available for sale under the ESPP shall be increased by the lesser of (i) two percent ( 2% ) of the Company’s outstanding shares of common stock as of the close of business on the last business day of the prior calendar year, not to exceed 600 shares, or (ii) a lesser amount determined by the Board of Directors. At March 31, 2016 there were 491 shares available for future issuance under the ESPP. Expense Information Under FASB ASC 718 The following table summarizes share-based compensation expense related to employee s under FASB ASC 718 for the three months ended March 31, 2016 and 2015 . This expense was allocated as follows:      Three Months Ended  March 31,  2016 2015  Cost of revenue $ 139 $ 90  Research and development expenses 479 289  Selling, general and administrative expenses 2,224 1,345  Total share-based compensation expense related to employees $ 2,842 $ 1,724

Segment and Geographic Informat

Segment and Geographic Information	3 Months Ended
	Mar. 31, 2016
Segment and Geographic Information [Abstract]
Segment and Geographic Information	10. SEGMENT AND GEOGRAPHIC INFORMATION The Company evaluates reporting segments in accordance with FASB ASC 280, “Segment Reporting”. The Company develops, manufactures, and sells devices designed primarily for the surgical ablation of cardiac tissue and systems designed for the exclusion of the left atrial appendage. These devices are developed and marketed to a broad base of medical centers in the United States and internationally. Management considers all such sales to be part of a single reportable segment. Revenue attributed to geographic areas is based on the location of the customers to whom products are sold. Revenue by geographic area was as follows:      Three Months Ended  March 31,  2016 2015  United States $ 28,272 $ 22,923  Europe 4,761 4,416  Asia 2,728 2,300  Other international 179 247  Total international 7,668 6,963  Total revenue $ 35,940 $ 29,886  Domestic revenue by product type was as follows:      Three Months Ended  March 31,  2016 2015  Open-heart ablation $ 13,968 $ 12,354  Minimally invasive ablation 6,725 4,347  AtriClip 6,848 5,503  Total ablation and AtriClip 27,541 22,204  Valve tools 731 719  Total domestic $ 28,272 $ 22,923  International revenue by product type was as follows:      Three Months Ended  March 31,  2016 2015  Open-heart ablation $ 4,472 $ 4,216  Minimally invasive ablation 2,164 1,968  AtriClip 865 671  Total ablation and AtriClip 7,501 6,855  Valve tools 167 108  Total international $ 7,668 $ 6,963  The majority of the Company’s long-lived assets are located in the United States.

Description of Business and S16

Description of Business and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2016
Description of Business and Summary of Significant Accounting Policies [Abstract]
Nature of the Business	Nature of the Business —AtriCure, Inc. was incorporated in the State of Delaware on October 31, 2000. The “Company” or “AtriCure” consists of AtriCure, Inc. and its wholly-owned subsidiaries. The Company is a leading atrial fibrillation (Afib) solutions partner providing innovative products, professional education and support for clinical science to reduce the economic and social burden of atrial fibrillation. The Company sells its products to medical centers globally through a direct sales force and distributors.
Basis of Presentation	Basis of Presentation —The accompanying interim financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (SEC). The accompanying interim financial statements are unaudited, but in the opinion of the Company’s management, contain all of the normal, recurring adjustments considered necessary to present fairly the financial position, results of operations and cash flows for the periods presented in conformity with accounting principles generally accepted in the United States of America (GAAP) applicable to interim periods. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been omitted or condensed. The Company believes the disclosures herein are adequate to make the information presented not misleading. Results of operations are not necessarily indicative of the results expected for the full fiscal year or for any future period. The accompanying Condensed Consolidated Financial Statements should be read in conjunction with the audited financial statements of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 filed with the SEC.
Principles of Consolidation	Principles of Consolidation —The Condensed Consolidated Financial Statements include the accounts of the Company, AtriCure, LLC, Endoscopic Technologies, LLC and nContact Surgical, LLC, the Company’s wholly-owned subsidiar ies, all organized in the State of Delaware, and AtriCure Europe B.V. (AtriCure Europe), the Company’s wholly-owned subsidiary incorporated in the Netherlands. All intercompany accounts and transactions have been eliminated in consolidation.
Cash and Cash Equivalents	Cash and Cash Equivalents —The Company considers highly liquid investments with maturities of three months or less at the date of acquisition as cash equivalents in the accompanying Condensed Consolidated Financial Statements.
Investments	Investments —The Company places its investments primarily in U.S. Government agencies and securities, corporate bonds and commercial paper. The Company classifies all investments as available-for-sale. Investments with maturities of less than one year are classified as short-term investments. Investments are recorded at fair value, with unrealized gains and losses recorded as accumulated other comprehensive income (loss). The Company recognizes gains and losses when these securities are sold using the specific identification method and includes them in interest income or expense in the Condensed Consolidated Statements of Operations and Comprehensive Loss.
Revenue Recognition	Revenue Recognition —The Company accounts for revenue in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 605, “Revenue Recognition” (ASC 605). The Company recognizes revenue when all of the following criteria are met: (i) there is persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured. Pursuant to the Company’s standard terms of sale, revenue is recognized when title to the goods and risk of loss transfers to customers and there are no remaining obligations that will affect the customers’ final acceptance of the sale. Generally, the Company’s standard terms of sale define the transfer of title and risk of loss to occur upon shipment to the respective customer. The Company generally does not maintain any post-shipping obligations to the recipients of the products. No installation, calibration or testing of products is performed by the Company subsequent to shipment to the customer in order to render it operational. Revenue includes shipping and handling revenue of $296 and $247 for the three months ended March 31, 2016 and 2015 , respectively. Cost of freight for shipments made to customers is included in cost of revenue. Sales and other value-added taxes collected from customers and remitted to governmental authorities are excluded from revenue. The Company sells its products primarily through a direct sales force, with certain international markets sold through distributors. Terms of sale are generally consistent for both end-users and distributors except that payment terms are generally net 30 days for end-users and net 60 days for distributors with limited exceptions.
Sales Returns and Allowances	Sales Returns and Allowances —The Company maintains a provision for sales returns and allowances to account for potential returns of defective or damaged products, products shipped in error and invoice adjustments. The Company estimates such provision on a quarterly basis based primarily on specific identification, in addition to estimating a general reserve based on historical experience. Increases to the provision result in a reduction of revenue. The provision is included in accrued liabilities in the Condensed Consolidated Balance Sheets.
Allowance for Doubtful Accounts Receivable	Allowance for Doubtful Accounts Receivable —The Company evaluates the collectability of accounts receivable to determine the appropriate reserve for doubtful accounts. In determining the amount of the reserve, the Company considers aging of account balances, historical credit losses, customer-specific information and other relevant factors. An increase to the allowance for doubtful accounts results in a corresponding increase in selling, general and administrative expense. The Company reviews accounts receivable and adjusts the allowance based on current circumstances and charges off uncollectible receivables against the allowance when all attempts to collect the receivable have failed. The Company’s history of write-offs against the allowance has not been significant.
Inventories	Inventories —Inventories are stated at the lower of cost or market using approximate costs based on the first-in, first-out cost method (FIFO) . Inventories consist of raw materials, work in process and finished goods. The Company’s industry is characterized by rapid product development and frequent new product introductions. Uncertain timing of product approvals, variability in product launch strategies and variation in product utilization all impact excess and obsolete inventory. An inventory allowance based on product usage is estimated and recorded quarterly for excess, slow moving and obsolete inventory, as well as inventory with a carrying value in excess of its net realizable value. An increase to the inventory reserve allowance results in a corresponding increase in cost of revenue. Write-offs are recorded when a product is destroyed. The Company’s history of write-offs against the reserve has not been significant. Inventories consist of the following:      March 31, December 31,  2016 2015  Raw materials $ 6,228 $ 6,159  Work in process 2,023 974  Finished goods 10,764 10,526  Inventories $ 19,015 $ 17,659 
Property and Equipment	Property and Equipment —Property and equipment is stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method of depreciation for financial reporting purposes and is applied over the estimated useful lives of the assets. The estimated useful life by major asset category is the following: generators and other capital equipment, machinery, equipment and vehicles is three to seven years, computer and other office equipment is three years, furniture and fixtures is three to seven years and leasehold improvements and equipment under capital leases are the shorter of their useful life or remaining lease term. The Company reassesses the useful lives of property and equipment annually, and assets are retired if they are no longer in service. Maintenance and repair costs are expensed as incurred. Generators and other capital equipment (such as the Company’s switchbox units and cryosurgical consoles) are placed with direct customers that use the Company’s disposable products. Depreciation of such assets is included in cost of revenue. The estimated useful lives of this equipment are based on anticipated usage by customers and the timing and impact of expected new technology rollouts by the Company. To the extent the Company experiences changes in the usage of this equipment or introduces new technologies, the estimated useful lives of this equipment may change in a future period. Depreciation related to these generators was $836 and $620 for the three months ended March 31, 2016 and 2015 , respectively. As of March 31, 2016 and December 31, 2015 , the net carrying amount of loaned equipment included in net property and equipment in the Condensed Consolidated Balance Sheets was $5,393 and $5,447 , respectively. The Company reviews property and equipment for impairment using its best estimates based on reasonable and supportable assumptions and projections.
Intangible Assets	Intangible Assets —Intangible assets with determinable useful lives are amortized on a straight-line basis over the estimated periods benefited. Included in intangible assets is In Process Research and Development (IPR&D). The Company defines IPR&D as the value of acquired technology which has not yet reached technological feasibility. The primary basis for determining the technological feasibility is obtaining specific regulatory approvals. The estimated fair value of IPR&D acquired in a business combination is capitalized as an indefinite-lived intangible asset until completion or abandonment of the IPR&D project. Upon completion of the development project, the IPR&D is amortized over its estimated useful life. If the IPR&D project is abandoned, the related IPR&D asset is written off. The estimated fair value of IPR&D was determined using an income approach model. IPR&D represents an estimate of the fair value of the PMA approval that could result from the CONVERGE IDE clinical trial. The Company reviews intangible assets for impairment using its best estimates based on reasonable and supportable assumptions and projections.
Goodwill	Goodwill— Goodwill represents the excess of purchase price over the fair value of the net assets acquired in business combinations. The Company tests goodwill for impairment annually on November 30, or more often if impairment indicators are present. The Company’s goodwill is accounted for in a single reporting unit representing the Company as a whole.
Other Current Liabilities and Current Maturities of Capital Leases	Other Current Liabilities and Current Maturities of Capital Leases— As of March 31, 201 6 , o ther current liabilities consisted of a financing obligation related to the construction of the Company’s new headquarters. Current maturities of capital leases consist of capital lease obligations with maturities of less than one year (see Note 6 – Indebtedness).
Other Noncurrent Liabilities	Other Noncurrent Liabilities— Other noncurrent liabilities include contingent consideration recorded in business combinations, as well as long-term deferred revenues and other contractual obligations.
Other Income	Other Income — Other income consists primarily of foreign currency transaction gains and losses. The Company recorded net foreign currency transaction gains (losses) of $(80) and $(163) for the three months ended March 31, 2016 and 2015 , respectively, in connection with settlements of its intercompany balance with AtriCure Europe and invoices transacted in British Pounds.
Taxes	Taxes —Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rates is recognized in the period that includes the enactment date. The Company’s estimate of the valuation allowance for deferred tax assets requires it to make significant estimates and judgments about its future operating results. Deferred tax assets are reduced by valuation allowances if, based on the consideration of all available evidence, it is more-likely-than-not that some portion of the deferred tax asset will not be realized. Significant weight is given to evidence that can be objectively verified. The Company evaluates deferred tax assets on a quarterly basis to determine if valuation allowances are required by considering all available evidence. Deferred tax assets are realized by having sufficient future taxable income to allow the related tax benefits to reduce taxes otherwise payable. The sources of taxable income that may be available to realize the benefit of deferred tax assets are future reversals of existing taxable temporary differences, future taxable income, exclusive of reversing temporary differences and carryforwards, taxable income in carry-back years and tax planning strategies that are both prudent and feasible. In evaluating whether to record a valuation allowance, the applicable accounting standards deem that the existence of cumulative losses in recent years is a significant piece of objectively verifiable negative evidence that must be overcome by objectively verifiable positive evidence to avoid the need to record a valuation allowance. The Company has recorded a full valuation allowance against its net deferred tax assets as it is more likely than not that the benefit of the deferred tax assets will not be recognized in future periods. A provision of The Patient Protection and Affordable Care Act enacted in 2010, as amended (Patient Act), requires manufacturers of medical devices to pay an excise tax on all U.S. medical device sales. In December 2015, the U.S. gove rnment approved the suspension of the excise tax on medical device sales beginning January 1, 2016 through December 31, 2017. The Company’s expense related to the medical device excise tax, which was recorded in cost of revenue, was $0 and $155 for the three months ended March 31, 2016 and 2015 , respectively.
Net Loss Per Share	Net Loss Per Share —Basic and diluted net loss per share is computed in accordance with FASB ASC 260, “Earnings Per Share” (ASC 260) by dividing the net loss by the weighted average number of common shares outstanding during the period. Since the Company has experienced net losses for all periods presented, net loss per share excludes the effect of 4,480 and 4,320 stock options and restricted stock shares as of March 31, 2016 and 2015 , respectively, because they are anti-dilutive. Therefore the number of shares calculated for basic net loss per share is also used for the diluted net loss per share calculation.
Comprehensive Loss and Accumulated Other Comprehensive Loss	Comprehensive Loss and Accumulated Other Comprehensive Loss —In addition to net losses, the comprehensive loss includes foreign currency translation adjustments and unrealized gains and losses on investments. Accumulated other comprehensive income (loss) consisted of the following:      Three Months Ended  March 31,  2016 2015  Total accumulated other comprehensive loss at beginning of period $ (611) $ (348)  Unrealized Gains on Investments  Balance at beginning of period $ (39) $ (54)  Other comprehensive income (loss) before reclassifications 41 37  Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations — —  Balance at end of period $ 2 $ (17)  Foreign Currency Translation Adjustment  Balance at beginning of period $ (572) $ (294)  Other comprehensive income (loss) before reclassifications 281 (324)  Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations 5 (163)  Balance at end of period $ (286) $ (781)  Total accumulated other comprehensive loss at end of period $ (284) $ (798) 
Research and Development	Research and Development —Research and development costs are expensed as incurred. These costs include compensation and other internal and external costs associated with the development and research related to new and existing products or concepts, preclinical studies, clinical trials, healthcare compliance and regulatory affairs.
Advertising Costs	Advertising Costs — The Company expenses advertising costs as incurred. Advertising costs were not significant during the three months ended March 31, 2016 and 2015 .
Share-Based Compensation	Share-Based Compensation —The Company follows FASB ASC 718, “Compensation-Stock Compensation” (ASC 718) to record share-based compensation for all employee share-based payment awards, including stock options, restricted stock and stock purchases related to an employee stock purchase plan, based on estimated fair values. The Company’s share-based compensation expense recognized under ASC 718 for the three months ended March 31, 2016 and 2015 was $2,842 and $1,724 , respectively, on a before and after tax basis. ASC 718 requires companies to estimate the fair value of share-based payment awards on the date of grant using an option-pricing model. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in the Company’s Condensed Consolidated Statement of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures. ASC 718 requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The Company estimates the fair value of time-based options on the date of grant using the Black-Scholes option-pricing model (Black-Scholes model). The Company’s determination of fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price, as well as assumptions regarding a number of subjective variables. These variables include but are not limited to the Company’s expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors. The fair value of market-based performance option grants is estimated at the date of grant using a Monte-Carlo simulation. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in the Consolidated Statement of Operations and Comprehensive Loss. The Company estimates the fair value of restricted stock based upon the grant date closing market price of the Company’s common stock. The Company’s determination of fair value is affected by the Company’s stock price as well as assumptions regarding the number of shares expected to be granted. The Company also has an employee stock purchase plan (ESPP) which is available to all eligible employees as defined by the plan document. Under the ESPP, shares of the Company’s common stock may be purchased at a discount. The Company estimates the number of shares to be purchased under the ESPP and records compensation expense based upon the fair value of the stock at the beginning of the purchase period using the Black-Scholes model.
Use of Estimates	Use of Estimates —The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reporting period. Actual results could differ from those estimates.
Fair Value Disclosures	Fair Value Disclosures —The Company classifies and records cash and investments in U.S. government agencies and securities as Level 1 within the fair value hierarchy. Accounts receivable, short-term other assets, accounts payable and accrued liabilities are also classified as Level 1. The carrying amounts of these assets and liabilities approximate their fair value due to their relatively short-term nature. Cash equivalents and investments in corporate bonds are classified as Level 2 within the fair value hierarchy (see Note 3 – Fair Value for further information).

Description of Business and S17

Description of Business and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2016
Description of Business and Summary of Significant Accounting Policies [Abstract]
Summary Of Inventories	Inventories consist of the following:      March 31, December 31,  2016 2015  Raw materials $ 6,228 $ 6,159  Work in process 2,023 974  Finished goods 10,764 10,526  Inventories $ 19,015 $ 17,659 
Accumulated Other Comprehensive Income (Loss)	Accumulated other comprehensive income (loss) consisted of the following:      Three Months Ended  March 31,  2016 2015  Total accumulated other comprehensive loss at beginning of period $ (611) $ (348)  Unrealized Gains on Investments  Balance at beginning of period $ (39) $ (54)  Other comprehensive income (loss) before reclassifications 41 37  Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations — —  Balance at end of period $ 2 $ (17)  Foreign Currency Translation Adjustment  Balance at beginning of period $ (572) $ (294)  Other comprehensive income (loss) before reclassifications 281 (324)  Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations 5 (163)  Balance at end of period $ (286) $ (781)  Total accumulated other comprehensive loss at end of period $ (284) $ (798) 

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value [Abstract]
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2016 :      Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Total  Assets:  Money market funds $ — $ 13,041 $ — $ 13,041  U.S. government agencies and securities 1,580 — — 1,580  Corporate bonds — 7,125 — 7,125  Total assets $ 1,580 $ 20,166 $ — $ 21,746  Liabilities:  Acquisition-related contingent consideration — — 40,207 40,207  Total liabilities $ — $ — $ 40,207 $ 40,207 There were no changes in the levels or methodology of measurement of financial assets and liabilities during the three month period ended March 31, 2016 . In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2015 :      Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Total  Assets:  Money market funds $ — $ 18,572 $ — $ 18,572  U.S. government agencies and securities 1,590 — — 1,590  Corporate bonds — 16,930 — 16,930  Total assets $ 1,590 $ 35,502 $ — $ 37,092  Liabilities:  Acquisition-related contingent consideration — — 40,207 40,207  Total liabilities $ — $ — $ 40,207 $ 40,207  There were no changes in the levels or methodology of measurement of financial assets and liabilities during the twelve months ended December 31, 2015 .
Level 3 Fair Value Measurements Using Significant Other Unobservable Inputs for Acquisition-Related Contingent Consideration	The following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for acquisition-related contingent consideration as of March 31, 2016:    Beginning Balance – January 1, 2016 $ 40,207  Amounts acquired —  Transfers in (out) of Level 3 —  Changes in fair value included in earnings —  Ending Balance – March 31, 2016 $ 40,207 The following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for acquisition-related contingent consideration as of December 31, 2015 :      Beginning Balance – January 1, 2015 $ —  Amounts acquired 40,207  Transfers in (out) of Level 3 —  Changes in fair value included in earnings —  Ending Balance – December 31, 2015 $ 40,207 

Intangible Assets (Tables)

Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2016
Intangible Assets [Abstract]
Company's Intangible Assets with Definite Lives	The following table provides a summary of the Company’s intangible assets:      March 31, December 31,  2016 2015  Cost Accumulated Amortization Cost Accumulated Amortization   Non-compete agreement $ 100 $ 100 $ 100 $ 100  Fusion technology 9,242 2,079 9,242 1,848  Clamp & probe technology 829 622 829 552  Estech trade name 208 208 208 208  SUBTLE access technology 2,179 206 2,179 96  IPR&D 44,021 — 44,021 —  Total $ 56,579 $ 3,215 $ 56,579 $ 2,804 
Future Amortization Expense Related to Intangible Assets with Definite Lives	Future amortization expense related to intangible assets with definite lives is projected as follows:      2016 $ 1,233 April 1, 2016 through December 31, 2016  2017 1,367  2018 1,367  2019 1,367  2020 1,235  2021 and thereafter 2,774  Total $ 9,343 

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2016
Accrued Liabilities [Abstract]
Accrued Liabilities	Accrued liabilities consisted of the following:      March 31, December 31,  2016 2015  Accrued payroll and employee-related expenses $ 4,694 $ 4,021  Accrued commissions 3,045 6,061  Accrued taxes and value-added taxes payable 2,214 912  Accrued bonus 1,565 6,088  Other accrued liabilities 807 723  Accrued royalties 398 382  Sales returns allowance 208 207  Total $ 12,931 $ 18,394 

Indebtedness (Tables)

Indebtedness (Tables)	3 Months Ended
	Mar. 31, 2016
Indebtedness [Abstract]
Future Maturities on Capital Lease Obligations	Future maturities on capital lease obligations are projected as follows:      2016 $ 1,065 April 1, 2016 through December 31, 2016  2017 1,425  2018 1,439  2019 1,457  2020 1,479  2021 and thereafter 15,894  Total payments $ 22,759  Imputed interest (8,705)  Net capital lease obligations, of which $462 is current and $13,592 is noncurrent $ 14,054 

Equity Compensation Plans (Tabl

Equity Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2016
Equity Compensation Plans [Abstract]
Share-Based Compensation Expense Related to Employee Share-Based Compensation	The following table summarizes share-based compensation expense related to employee s under FASB ASC 718 for the three months ended March 31, 2016 and 2015 . This expense was allocated as follows:      Three Months Ended  March 31,  2016 2015  Cost of revenue $ 139 $ 90  Research and development expenses 479 289  Selling, general and administrative expenses 2,224 1,345  Total share-based compensation expense related to employees $ 2,842 $ 1,724 

Segment and Geographic Inform23

Segment and Geographic Information (Tables)	3 Months Ended
	Mar. 31, 2016
Segment and Geographic Information [Abstract]
Revenue by Geographic Area	Revenue by geographic area was as follows:      Three Months Ended  March 31,  2016 2015  United States $ 28,272 $ 22,923  Europe 4,761 4,416  Asia 2,728 2,300  Other international 179 247  Total international 7,668 6,963  Total revenue $ 35,940 $ 29,886 
Revenue by Product Type	Domestic revenue by product type was as follows:      Three Months Ended  March 31,  2016 2015  Open-heart ablation $ 13,968 $ 12,354  Minimally invasive ablation 6,725 4,347  AtriClip 6,848 5,503  Total ablation and AtriClip 27,541 22,204  Valve tools 731 719  Total domestic $ 28,272 $ 22,923  International revenue by product type was as follows:      Three Months Ended  March 31,  2016 2015  Open-heart ablation $ 4,472 $ 4,216  Minimally invasive ablation 2,164 1,968  AtriClip 865 671  Total ablation and AtriClip 7,501 6,855  Valve tools 167 108  Total international $ 7,668 $ 6,963 

Description of Business and S24

Description of Business and Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Description Of Business And Significant Accounting Policies [Line Items]
Shipping and handling revenue	$ 296	$ 247
Payment terms for end-users	30 days
Payment terms for distributors	60 days
Depreciation	$ 1,800	1,008
Net carrying amount of loaned equipment	31,155		$ 31,279
Foreign currency transaction (losses) gains	(5)	251
Company's expense related to the medical device excise tax	$ 0	$ 155
Options, restricted stock and performance based shares excluded from calculation of net loss per share	4,480	4,320
Share-based compensation expense recognized	$ 2,842	$ 1,724
Subsidiaries [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Foreign currency transaction (losses) gains	$ (80)	(163)
Computer and Other Office Equipment [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category	3 years
Generators [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Depreciation	$ 836	$ 620
Carrying Amount of Loaned Equipment [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Net carrying amount of loaned equipment	$ 5,393		$ 5,447
Short-term Debt [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Maturity period of short term investment	1 year
Minimum [Member] | Generators and Other Capital Equipment, Machinery, Equipment and Vehicles [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category	3 years
Minimum [Member] | Furniture and Fixtures [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category	3 years
Maximum [Member] | Generators and Other Capital Equipment, Machinery, Equipment and Vehicles [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category	7 years
Maximum [Member] | Furniture and Fixtures [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category	7 years

Description of Business and S25

Description of Business and Summary of Significant Accounting Policies (Summary Of Inventories) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Description of Business and Summary of Significant Accounting Policies [Abstract]
Raw materials	$ 6,228	$ 6,159
Work in process	2,023	974
Finished goods	10,764	10,526
Inventories	$ 19,015	$ 17,659

Description of Business and S26

Description of Business and Summary of Significant Accounting Policies (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive (loss) income, at beginning of period	$ (611)	$ (348)
Total accumulated other comprehensive (loss) income, at end of period	(284)	(798)
Unrealized (Losses) Gains on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive (loss) income, at beginning of period	(39)	(54)
Other comprehensive income (loss) before reclassifications	$ 41	$ 37
Amounts reclassified from accumulated other comprehensive income (loss) to other income
Total accumulated other comprehensive (loss) income, at end of period	$ 2	$ (17)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total accumulated other comprehensive (loss) income, at beginning of period	(572)	(294)
Other comprehensive income (loss) before reclassifications	281	(324)
Amounts reclassified from accumulated other comprehensive income (loss) to other income	5	(163)
Total accumulated other comprehensive (loss) income, at end of period	$ (286)	$ (781)

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - nContact Surgical [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Oct. 13, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquisition-related contingent consideration		$ 50,000
Entitled sales-based contingent consideration on revenue in excess of annual growth through 2019	25.00%

Fair Value (Financial Assets an

Fair Value (Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Assets:
Total assets	$ 21,746	$ 37,092
Liabilities:
Acquisition-related contingent consideration	40,207	40,207
Total liabilities	40,207	40,207
Money Market Funds [Member]
Assets:
Total assets	13,041	18,572
U.S. Government Agencies and Securities [Member]
Assets:
Total assets	1,580	1,590
Corporate Bonds [Member]
Assets:
Total assets	7,125	16,930
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Total assets	1,580	$ 1,590
Liabilities:
Acquisition-related contingent consideration
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Government Agencies and Securities [Member]
Assets:
Total assets	1,580	$ 1,590
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets	20,166	$ 35,502
Liabilities:
Acquisition-related contingent consideration
Significant Other Observable Inputs (Level 2) [Member] | Money Market Funds [Member]
Assets:
Total assets	13,041	$ 18,572
Significant Other Observable Inputs (Level 2) [Member] | Corporate Bonds [Member]
Assets:
Total assets	7,125	16,930
Significant Other Unobservable Inputs (Level 3) [Member]
Liabilities:
Acquisition-related contingent consideration	40,207	40,207
Total liabilities	$ 40,207	$ 40,207

Fair Value (Level 3 Fair Value

Fair Value (Level 3 Fair Value Measurements Using Significant Other Unobservable Inputs for Acquisition-Related Contingent Consideration) (Details) - Significant Other Unobservable Inputs (Level 3) [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 40,207
Amounts acquired		$ 40,207
Transfers in (out) of Level 3
Changes in fair value included in earnings
Ending Balance	$ 40,207	$ 40,207

Intangible Assets (Narative) (D

Intangible Assets (Narative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Intangible Assets [Abstract]
Amortization of intangible assets	$ 411	$ 303

Intangible Assets (Company's In

Intangible Assets (Company's Intangible Assets with Definite Lives) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Cost	$ 56,579	$ 56,579
Accumulated Amortization	3,215	2,804
Non-Compete Agreement [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	100	100
Accumulated Amortization	100	100
Fusion Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	9,242	9,242
Accumulated Amortization	2,079	1,848
Clamp and Probe Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	829	829
Accumulated Amortization	622	552
Estech Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	208	208
Accumulated Amortization	208	208
SUBTLE Access Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	2,179	2,179
Accumulated Amortization	206	96
IPR&D [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	$ 44,021	$ 44,021

Intangible Assets (Future Amort

Intangible Assets (Future Amortization Expense Related to Intangible Assets with Definite Lives) (Details) $ in Thousands	Mar. 31, 2016USD ($)
Intangible Assets [Abstract]
2,016	$ 1,233
2,017	1,367
2,018	1,367
2,019	1,367
2,020	1,235
2021 and thereafter	2,774
Total	$ 9,343

Accrued Liabilities (Accrued Li

Accrued Liabilities (Accrued Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accrued Liabilities [Abstract]
Accrued payroll and employee-related expenses	$ 4,694	$ 4,021
Accrued commissions	3,045	6,061
Accrued taxes and value-added taxes payable	2,214	912
Accrued bonus	1,565	6,088
Other accrued liabilities	807	723
Accrued royalties	398	382
Sales returns allowance	208	207
Total	$ 12,931	$ 18,394

Indebtedness (Narrative) (Detai

Indebtedness (Narrative) (Details) $ in Thousands	Apr. 25, 2016USD ($)	Mar. 31, 2016USD ($)loan
Line of Credit Facility [Line Items]
Cost of assets under lease		$ 14,462
Accumulated amortization on the capital leases		597
Maximum [Member]
Line of Credit Facility [Line Items]
Letter of credit required to landlord		1,250
Silicon Valley Bank Agreement [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity		$ 15,000
Credit facility maturity date		Apr. 30, 2018
Line of credit, outstanding		$ 15,000
Line of credit, availability		$ 0
Applicable interest rate		3.50%
Silicon Valley Bank, Second Amended And Restated Loan Agreement [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility maturity date		Apr. 30, 2021
Interest rate description		The term loan accrues interest at the Prime Rate and is subject to an additional 4.0% fee on the original $25,000 term loan principal amount at maturity. The revolving line of credit is subject to an annual commitment fee of $50, and any borrowings bear interest at the Prime Rate.
Silicon Valley Bank, Second Amended And Restated Loan Agreement [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	$ 15,000
Line of credit, outstanding	$ 25,000
Line of Credit Facility, Expiration Period	5 years
Principal payment starting period after inception of loan to maturity	12 months
Upon certain conditions met, deferred loan payment period	6 months
Additional fee on total term loan	4.00%
Annual commitment fee	$ 50
Computer And Office Equipment [Member]
Line of Credit Facility [Line Items]
Capital lease expiration period		Dec. 31, 2030
Mason Lease [Member]
Line of Credit Facility [Line Items]
Lease term period		15 years
Number of renewal options | loan		3
Lease renewal option period		5 years

Indebtedness (Future Maturities

Indebtedness (Future Maturities on Capital Lease Obligations) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Indebtedness [Abstract]
2,016	$ 1,065
2,017	1,425
2,018	1,439
2,019	1,457
2,020	1,479
2021 and thereafter	15,894
Total payments	22,759
Imputed interest	(8,705)
Net capital lease obligations, of which $462 is current and $13,592 is noncurrent	14,054
Net capital lease obligations, current	462
Net capital lease obligations, noncurrent	$ 13,592	$ 13,710

Commitments and Contingencies (

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Commitments and Contingencies [Line Items]
Royalty expense	$ 441	$ 427
Minimum [Member]
Commitments and Contingencies [Line Items]
Royalty rates	0.75%
Royalty agreement term	3 years
Maximum [Member]
Commitments and Contingencies [Line Items]
Royalty rates	5.00%
Royalty agreement term	20 years
Office, Manufacturing, Warehouse Facilities, And Equipment [Member]
Commitments and Contingencies [Line Items]
Operating leases expire at various terms	Dec. 31, 2021

Income Tax Provision (Narrative

Income Tax Provision (Narrative) (Details)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Provision [Abstract]
Effective tax rate	(0.05%)	(0.11%)

Equity Compensation Plans (Narr

Equity Compensation Plans (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of participants purchase limit	Participants may not purchase more than $25 of the Company's common stock in a calendar year and, effective January 1, 2014, may not purchase a value of more than 3 shares during an offering period.
Participants purchase limit shares	3,000
Offering period	6 months
2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiry of options from the date of grant	10 years
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiry of options from the date of grant	10 years
Shares reserved for issuance	8,949,000
2008 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company's common stock may be purchased at a discount	15.00%
Participants purchase limit value | $	$ 25
Shares available for sale under the ESPP increased	2.00%
Outstanding shares of common stock exceed	600,000
Shares available for future issuance under the ESPP	491,000
Employee Stock Option [Member] | 2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable period beginning	3 years
Employee Stock Option [Member] | 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable period beginning	3 years
Restricted Stock [Member] | 2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Restricted Stock [Member] | 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
First Anniversary Date Of Grant [Member] | Employee Stock Option [Member] | 2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage	25.00%
First Anniversary Date Of Grant [Member] | Employee Stock Option [Member] | 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage	25.00%
Four Years From Date Of Grant [Member] | Restricted Stock [Member] | 2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage	25.00%
Four Years From Date Of Grant [Member] | Restricted Stock [Member] | 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage	25.00%

Equity Compensation Plans (Shar

Equity Compensation Plans (Share-Based Compensation Expense Related to Employee Share-Based Compensation) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	$ 2,842	$ 1,724
Cost of Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	139	90
Research and Development Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	479	289
Selling, General and Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	$ 2,224	$ 1,345

Segment and Geographic Inform40

Segment and Geographic Information (Revenue by Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 35,940	$ 29,886
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	28,272	22,923
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	4,761	4,416
Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	2,728	2,300
Other International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	179	247
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 7,668	$ 6,963

Segment and Geographic Inform41

Segment and Geographic Information (Revenue by Product Type) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenue from External Customer [Line Items]
Revenue	$ 35,940	$ 29,886
United States [Member]
Revenue from External Customer [Line Items]
Revenue	28,272	22,923
United States [Member] | Open-heart Ablation [Member]
Revenue from External Customer [Line Items]
Revenue	13,968	12,354
United States [Member] | Minimally Invasive Ablation [Member]
Revenue from External Customer [Line Items]
Revenue	6,725	4,347
United States [Member] | AtriClip [Member]
Revenue from External Customer [Line Items]
Revenue	6,848	5,503
United States [Member] | Ablation and AtriClip [Member]
Revenue from External Customer [Line Items]
Revenue	27,541	22,204
United States [Member] | Valve Tools [Member]
Revenue from External Customer [Line Items]
Revenue	731	719
International [Member]
Revenue from External Customer [Line Items]
Revenue	7,668	6,963
International [Member] | Open-heart Ablation [Member]
Revenue from External Customer [Line Items]
Revenue	4,472	4,216
International [Member] | Minimally Invasive Ablation [Member]
Revenue from External Customer [Line Items]
Revenue	2,164	1,968
International [Member] | AtriClip [Member]
Revenue from External Customer [Line Items]
Revenue	865	671
International [Member] | Ablation and AtriClip [Member]
Revenue from External Customer [Line Items]
Revenue	7,501	6,855
International [Member] | Valve Tools [Member]
Revenue from External Customer [Line Items]
Revenue	$ 167	$ 108