AtriCure (ATRC) 10-K2 Mar 152014 FY Annual reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 20, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	ATRC
Entity Registrant Name	AtriCure, Inc.
Entity Central Index Key	1323885
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		27,590,646
Entity Public Float			$478.30

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$28,384	$14,892
Short-term investments	31,265	11,319
Accounts receivable, less allowance for doubtful accounts of $68 and $94, respectively	17,558	13,652
Inventories	14,257	10,214
Other current assets	2,044	2,410
Total current assets	93,508	52,487
Property and equipment, net	11,552	5,643
Long-term investments	8,894	7,914
Intangible assets, net	8,878	10,299
Goodwill	35,386	35,386
Other assets	186	218
Total Assets	158,404	111,947
Current liabilities:
Accounts payable	7,621	8,605
Accrued liabilities	14,041	16,070
Other current liabilities and current maturities of debt and capital leases	3,981	2,038
Total current liabilities	25,643	26,713
Long-term debt and capital leases	74	4,412
Other liabilities	149	8,218
Total Liabilities	25,866	39,343
Commitments and contingencies (Note 11)
Stockholders' Equity:
Common stock, $.001 par value, 90,000 shares authorized and 27,580 and 23,248 issued and outstanding, respectively	28	23
Additional paid-in capital	271,282	194,933
Accumulated other comprehensive loss	-348	-139
Accumulated deficit	-138,424	-122,213
Total Stockholders' Equity	132,538	72,604
Total Liabilities and Stockholders' Equity	$158,404	$111,947

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$68	$94
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	27,580,000	23,248,000
Common stock, shares outstanding	27,580,000	23,248,000

Consolidated_Statements_of_Ope

Consolidated Statements of Operations and Comprehensive Loss (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Revenue	$107,454	$81,889	$70,247
Cost of revenue	31,704	22,326	20,233
Gross profit	75,750	59,563	50,014
Operating expenses:
Research and development expenses	18,600	13,440	12,147
Selling, general and administrative expenses	73,510	57,014	45,065
Total operating expenses	92,110	70,454	57,212
Loss from operations	-16,360	-10,891	-7,198
Other income (expense):
Interest expense	-305	-566	-802
Interest income	96	16	11
Other	391	-3	505
Loss before income tax expense	-16,178	-11,444	-7,484
Income tax expense	-33	-18	-50
Net loss	-16,211	-11,462	-7,534
Basic and diluted net loss per share	($0.61)	($0.56)	($0.47)
Weighted average shares outstanding-basic and diluted	26,374	20,431	16,190
Comprehensive loss:
Unrealized losses on investments	-48	-7	-1
Foreign currency translation adjustment	-161	-209	115
Other comprehensive (loss) income	-209	-216	114
Net loss	-16,211	-11,462	-7,534
Comprehensive loss	($16,420)	($11,678)	($7,420)

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
In Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2011	$15,615	$16	$118,853	($103,217)	($37)
Beginning Balance, Shares at Dec. 31, 2011		16,369
Issuance of common stock under equity incentive plans	259	1	258
Issuance of common stock under equity incentive plans, Shares		438
Issuance of common stock under employee stock purchase plan	627		627
Issuance of common stock under employee stock purchase plan, Shares		89
Share-based employee compensation expense	3,468		3,468
Reclassification of non-employee option liability	49		49
Other comprehensive income	114				114
Net loss	-7,534			-7,534
Ending Balance at Dec. 31, 2012	12,500	17	123,157	-110,751	77
Ending Balance, Shares at Dec. 31, 2012		16,896
Issuance of common stock through public offering	26,872	4	26,868
Issuance of common stock through public offering, Shares		3,996
Issuance of common stock for Estech acquisition	39,720	2	39,718
Issuance of common stock for Estech acquisition, Shares		2,126
Issuance of common stock under equity incentive plans	1,320		1,320
Issuance of common stock under equity incentive plans, Shares		119
Issuance of common stock under employee stock purchase plan	790		790
Issuance of common stock under employee stock purchase plan, Shares		111
Share-based employee compensation expense	3,080		3,080
Other comprehensive income	-216				-216
Net loss	-11,462			-11,462
Ending Balance at Dec. 31, 2013	72,604	23	194,933	-122,213	-139
Ending Balance, Shares at Dec. 31, 2013		23,248
Issuance of common stock through public offering	65,830	4	65,826
Issuance of common stock through public offering, Shares		3,661
Issuance of common stock under equity incentive plans	1,586	1	1,585
Issuance of common stock under equity incentive plans, Shares		586
Issuance of common stock under employee stock purchase plan	1,320		1,320
Issuance of common stock under employee stock purchase plan, Shares		85
Share-based employee compensation expense	7,571		7,571
Reclassification of non-employee option liability	47		47
Other comprehensive income	-209				-209
Net loss	-16,211			-16,211
Ending Balance at Dec. 31, 2014	$132,538	$28	$271,282	($138,424)	($348)
Ending Balance, Shares at Dec. 31, 2014		27,580

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net loss	($16,211)	($11,462)	($7,534)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Share-based compensation expense	7,571	3,080	3,468
Depreciation	3,353	2,008	1,886
Amortization of intangible assets	1,421	12	13
Amortization of deferred financing costs	113	115	100
Loss (gain) on disposal of property and equipment	118	-6	40
Loss from foreign exchange on intercompany transactions	544
Amortization/accretion on investments	500	49	12
Change in allowance for doubtful accounts	-34	-14	1
Change in fair value of contingent consideration	-8,032
Other	95
Changes in assets and liabilities:
Accounts receivable	-4,168	-1,248	-417
Inventories	-4,343	-2,288	865
Other current assets	307	-1,257	57
Accounts payable	-944	1,445	-132
Accrued liabilities	-1,847	4,114	-97
Other non-current assets and non-current liabilities	-43	230	-198
Net cash used in operating activities	-21,600	-5,222	-1,936
Cash flows from investing activities:
Purchases of available-for-sale securities	-41,107	-21,243	-9,236
Sales and maturities of available-for-sale securities	19,614	6,200	9,400
Purchases of property and equipment	-9,207	-2,864	-2,985
Proceeds from sale of property and equipment	77	48	24
Cash acquired through business combination		3,708
Net cash used in investing activities	-30,623	-14,151	-2,797
Cash flows from financing activities:
Proceeds from sale of stock, net of offering costs of $257 and $212, respectively	65,830	26,872
Payments on debt and capital leases	-6,382	-2,055	-8,096
Proceeds from construction financing obligation	3,699
Payment of debt fees and premium on retirement of debt	-181	-99	-127
Proceeds from stock option exercises	1,916	1,718	659
Shares repurchased for payment of taxes on stock awards	-331	-398	-401
Proceeds from issuance of common stock under employee stock purchase plan	1,320	790	627
Proceeds from borrowings of debt			10,000
Net cash provided by financing activities	65,871	26,828	2,662
Effect of exchange rate changes on cash	-156	-316	65
Net increase (decrease) in cash and cash equivalents	13,492	7,139	-2,006
Cash and cash equivalents-beginning of period	14,892	7,753	9,759
Cash and cash equivalents-end of period	28,384	14,892	7,753
Supplemental cash flow information:
Cash paid for interest	115	473	607
Cash paid for income taxes	146	30	14
Noncash investing and financing activities:
Accrued purchases of property and equipment	547	282	10
Assets acquired through capital lease	47	68	65
Capital lease asset early termination	38	24	13
Stock issuance for Estech acquisition		39,720
Contingent consideration for acquisition of Estech		$8,032

Consolidated_Statements_of_Cas1

Consolidated Statements of Cash Flows (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement of Cash Flows [Abstract]
Offering cost for sale of stock	$257	$212

Description_of_Business_and_Su

Description of Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Description of Business and Summary of Significant Accounting Policies	1. DESCRIPTION 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 an innovator in surgical treatments for atrial fibrillation (Afib) and left atrial appendage management (LAAM). The Company sells its products to medical centers globally through a direct sales force and distributors.
	Principles of Consolidation— The Consolidated Financial Statements include the accounts of the Company, AtriCure, LLC, the Company’s wholly-owned subsidiary organized in the State of Delaware, Endoscopic Technologies, LLC, the Company’s wholly-owned subsidiary 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 Consolidated Financial Statements. Money market funds are included in cash and cash equivalents.
	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 to 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 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 $952, $786 and $723 in 2014, 2013 and 2012, 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.
	Sales Returns and Allowances—While the Company’s products do not have return rights, 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 price adjustments. The Company estimates such provision quarterly based primarily on a specific identification basis, in addition to estimating a general reserve. Increases to the provision result in a reduction of revenue. The provision is included in accrued liabilities in the Consolidated Balance Sheets.
	Allowance for Uncollectible Accounts Receivable—The Company evaluates the collectability of accounts receivable in order 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 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) and 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 reserve 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. Write-offs are recorded when a product is destroyed. The Company’s history of write-offs against the reserve has not been significant.
	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 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 useful lives of property and equipment annually, and assets are retired if they are no longer being used. Maintenance and repair costs are expensed as incurred.
	Generators and other capital equipment (such as the Company’s switchbox units and cryosurgical consoles) are loaned at no cost to 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.
	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. The Company’s amortization term for a non-compete agreement is eight years. Fusion technology is being amortized over ten years. Clamp and probe technology is being amortized over three years. The Estech trade name was amortized over one year. 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 uses readily available market information and income valuation approaches to estimate the fair value of the reporting unit. The income valuation approach is developed using the Company’s best estimates based on reasonable and supportable assumptions and projections. 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 Debt and Capital Leases—Other current liabilities consists of a financing obligation related to the construction of the Company’s new headquarters (see Note 11 – Commitments and Contingencies). Current maturities of debt and capital leases consist of debt and capital lease obligations with maturities of less than one year (see Note 10 – Indebtedness).
	Other Income (Loss)—Other income (loss) consists primarily of foreign currency transaction gains and losses, grant income and non-employee option gains and losses related to the fair market value change for fully vested options outstanding for consultants which are accounted for as free-standing derivatives.
	The Company recorded foreign currency transaction (losses) gains of ($523), $269 and ($83) for the years ended December 31, 2014, 2013 and 2012, respectively, primarily in connection with settlements of its intercompany balances with AtriCure Europe.
	The Company periodically is awarded grants to support research and development or education activities. The Company recognizes grant income when the funds are earned. The Company recorded grant income of $731, $0 and $409 during 2014, 2013 and 2012, respectively.
	The Company historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. Because the non-employee options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the options to be partially net-cash settled, these options, when vested, are no longer eligible for equity classification and are, thus, subsequently accounted for as derivative liabilities under FASB ASC 815, “Derivatives and Hedging” (ASC 815) until the awards are ultimately either exercised or forfeited. Accordingly, the vested non-employee options are classified as liabilities and remeasured at fair value through earnings at each reporting period. During the years ended December 31, 2014, 2013 and 2012, ($183), $272 and ($179), respectively, of (income) expense was recorded as a result of the remeasurement of the fair value of these fully vested stock options.
	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 (Affordable Care Act), required manufacturers of medical devices to pay an excise tax on all U.S. medical device sales beginning in January 2013. The Company’s expense related to the medical device excise tax, which was recorded in cost of revenue, was $592 and $417 for the years ended December 31, 2014 and 2013, 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 3,772, 2,721 and 3,676 stock options, restricted stock and performance-based shares as of December 31, 2014, 2013, and 2012, 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 Income (Loss)—In addition to net loss, comprehensive loss includes foreign currency exchange rate adjustments and unrealized gains and losses on investments.
	Accumulated other comprehensive income (loss) consists of the following:


		2014			2013			2012
	Total accumulated other comprehensive income (loss) at beginning of period	$	(139	)	$	77		$	(37	)
	Unrealized (losses) gains on investments
	Balance at beginning of period	$	(6	)	$	1		$	2
	Other comprehensive loss before reclassifications		(48	)		(7	)		(1	)
	Amounts reclassified from accumulated other comprehensive income (loss) to other income		—			—			—

	Balance at end of period	$	(54	)	$	(6	)	$	1


	Foreign currency translation adjustment
	Balance at beginning of period	$	(133	)	$	76		$	(39	)
	Other comprehensive income (loss) before reclassifications		362			(478	)		198
	Amounts reclassified from accumulated other comprehensive income (loss) to other income		(523	)		269			(83	)

	Balance at end of period	$	(294	)	$	(133	)	$	76

	Total accumulated other comprehensive (loss) income at end of period	$	(348	)	$	(139	)	$	77

	Research and Development Costs— 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 years ended December 31, 2014, 2013 and 2012, respectively.
	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, performance shares 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 years ended December 31, 2014, 2013 and 2012 was $7,571, $3,080 and $3,468, respectively, on a before and after tax basis.
	FASB 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 Consolidated Statement of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures. FASB 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.
	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 vest.
	The Company also has an employee stock purchase plan (ESPP or Plan) which is available to all eligible employees as defined by the Plan. 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 Plan at the beginning of each purchase period. Compensation expense based upon the fair value of the stock at the beginning of the purchase period calculated using the Black-Scholes model is recognized over each purchase period.
	Also included in share-based compensation are stock options the Company has historically issued to non-employee consultants as a form of compensation for services provided to the Company. These options are accounted for as derivative liabilities under FASB ASC 815 until the stock options are ultimately either exercised or forfeited. Accordingly, the vested non-employee consultant stock options are classified as liabilities and remeasured at fair value through earnings at each reporting period (see Note 3—Fair Value and Note 15—Equity Compensation Plans for further information).
	Use of Estimates—The preparation of the financial statements in conformity with accounting principles generally accepted in the United States of America (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 short-term 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 expenses 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. Other assets and other liabilities are classified as Level 1 within the fair value hierarchy. Cash equivalents and short-term investments in commercial paper 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 non-employee stock options are developed using Company data. When an input is changed, the Black-Scholes model is updated and the results are analyzed for reasonableness. Significant unobservable inputs with respect to the fair value measurement of the Level 3 acquisition-related contingent consideration are developed using Company data. When an input is changed, the expected present value calculation is updated and the results are analyzed for reasonableness.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	12 Months Ended
Recent Accounting Pronouncements	Dec. 31, 2014
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	2. RECENT ACCOUNTING PRONOUNCEMENTS
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. The ASU is effective for interim and annual reporting periods beginning after December 15, 2016. Early adoption is not permitted. 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.

Fair_Value

Fair Value	12 Months Ended
Fair Value	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value	3. FAIR VALUE
	FASB ASC 820, “Fair Value Measurements and Disclosures” (ASC 820), defines fair value as the 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 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 derivatives are estimated on the grant date using the Black-Scholes model and they are revalued at the end of each reporting period using the Black-Scholes model. The fair value of the Company’s Level 3 contingent consideration was estimated on the acquisition date of Endoscopic Technologies, Inc. and was revalued at the end of each subsequent reporting period (see Note 5 – Business Combinations for further information).

	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, 2014:


			Quoted Prices in				Significant Other			Significant Other		Total
			Active Markets for				Observable Inputs			Unobservable
			Identical Assets				(Level 2)			Inputs
			(Level 1)							(Level 3)
	Assets:
	Money market funds		$	—			$	23,692		$	—	$	23,692
	Commercial paper			—				1,800			—		1,800
	U.S. government agencies and securities			3,022				—			—		3,022
	Corporate bonds			—				35,337			—		35,337

	Total assets		$	3,022			$	60,829		$	—	$	63,851

	Liabilities:
	Derivative instruments		$	—			$	—		$	120	$	120
	Acquisition-related contingent consideration			—				—			—		—

	Total liabilities		$	—			$	—		$	120	$	120

	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, 2013:


			Quoted Prices in				Significant Other			Significant Other		Total
			Active Markets for				Observable Inputs			Unobservable
			Identical Assets				(Level 2)			Inputs
			(Level 1)							(Level 3)
	Assets:
	Money market funds		$	—			$	4,295		$	—	$	4,295
	Commercial paper			—				2,598			—		2,598
	U.S. government agencies and securities			4,145				—			—		4,145
	Corporate bonds			—				12,490			—		12,490

	Total assets		$	4,145			$	19,383		$	—	$	23,528

	Liabilities:
	Derivative instruments		$	—			$	—		$	350	$	350
	Acquisition-related contingent consideration			—				—			8,032		8,032

	Total liabilities		$	—			$	—		$	8,382	$	8,382

	There were no changes in the levels of financial assets and liabilities during the twelve months ended December 31, 2014 and 2013, and there were no changes in the methodologies used to determine the levels of financial assets during the twelve months ended December 31, 2014 and 2013.
	Derivative Instruments. Vested non-employee options historically issued by the Company are accounted for as derivative liabilities and remeasured at fair value through earnings at each reporting period until exercised or forfeited. The fair value of these options is estimated at each reporting date using the Black-Scholes model subject to change in stock price utilizing assumptions of risk-free interest rate, contractual life of option, expected volatility and dividend yield. Due to the lack of certain observable market quotes, the Company utilizes valuation models that rely on some Level 3 inputs. The Company’s estimate of volatility is based on the Company’s trading history. See Note 15—Equity Compensation Plans for further information.

	The fair value of the Level 3 derivative instruments is estimated using the Black-Scholes model including the following assumptions:


			As of December 31, 2014		As of December 31, 2013
	Risk-free interest rate		0.07%		0.11% - 1.32%
	Expected life of option (years)		0.7		0.75 - 4.10
	Expected volatility of stock		39.91%		70.00%
	Dividend yield		0.00%		0.00%
	In accordance with ASC 820, the following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for derivative instruments as of December 31:


		2014				2013			2012
Beginning Balance—January 1		$	350			$	78		$	208
Total (gains) losses included in earnings			(183	)			272			(179	)
Exercises			(47	)			—			(50	)
Reclassification from equity to liability when fully vested			—				—			99

Ending Balance—December 31		$	120			$	350		$	78

Acquisition-Related Contingent Consideration. The Company acquired Endoscopic Technologies, Inc. (Estech) on December 31, 2013. The aggregate consideration paid to Estech shareholders includes up to $26,000 of contingent consideration to be paid based on the achievement of certain performance-based milestones in 2014 and 2015. The fair value of the contingent consideration was measured using an expected present value approach to estimate an expected value, which, in statistical terms, is the weighted average of a discrete random variable’s possible values, with the respective probabilities as the weights. This fair value measurement is based on significant inputs not observable in the market and thus represents a Level 3 measurement within the fair value hierarchy. Using this valuation technique, the fair value of the contingent consideration was determined to be $0 and $8,032 as of December 31, 2014 and 2013, respectively.
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:


		2014				2013			2012
Beginning Balance—January 1		$	8,032			$	—		$	—
Amounts acquired			—				8,032			—
Transfers in (out) of Level 3			—				—			—
Changes in fair value included in earnings			(8,032	)			—			—

Ending Balance—December 31		$	—			$	8,032		$	—

Investments

Investments	12 Months Ended
Investments	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investments	4. INVESTMENTS
	Investments as of December 31, 2014 consisted of the following:


		Cost Basis		Unrealized			Fair Value
		Cost Basis		Gains (Losses)			Fair Value
	Corporate bonds	$	35,389	$	(52	)	$	35,337
	U.S. government agencies and securities		3,024		(2	)		3,022
	Commercial paper		1,800		—			1,800

	Total	$	40,213	$	(54	)	$	40,159

	Investments as of December 31, 2013 consisted of the following:


		Cost Basis		Unrealized			Fair Value
		Cost Basis		Gains (Losses)			Fair Value
	Corporate bonds	$	12,498	$	(8	)	$	12,490
	U.S. government agencies and securities		4,143		2			4,145
	Commercial paper		2,598		—			2,598

	Total	$	19,239	$	(6	)	$	19,233

	The Company has not experienced any significant realized gains or losses on its investments in the periods presented in the Consolidated Statements of Operations and Comprehensive Loss. Long term investments held by the Company have maturities between one and five years at both December 31, 2014 and 2013.

Business_Combination

Business Combination	12 Months Ended
Business Combination	Dec. 31, 2014
Business Combinations [Abstract]
Business Combination	5. BUSINESS COMBINATION
	On December 31, 2013 the Company completed its acquisition of Estech. The Company acquired 100% of the outstanding common and preferred shares and voting interest of Estech. Estech was incorporated in 1996 and has been operating since that time developing and marketing a broad portfolio of innovative medical devices and disposables that enable cardiac surgeons worldwide to perform a variety of traditional and minimally invasive surgical procedures. AtriCure’s management believes the acquisition of Estech will expand the Company’s presence and reinforce its commitment to the atrial fibrillation market. The combination of the two companies enhances the Company’s leadership and intellectual property position across surgical ablation and epicardial left atrial appendage closure and accelerates the availability of broader surgical ablation offerings through the combination of Estech’s sales and marketing and research and development capabilities worldwide under AtriCure.
	The total consideration paid to Estech’s former shareholders in the acquisition was $34,000, paid through the issuance of 2,126,343 shares of AtriCure common stock with a value of $15.99 per share. The share value was calculated using the volume-weighted average share price of the ten days prior to the date of the signing of the merger agreement. Based on the Company’s closing stock price of $18.68 on December 31, 2013, the value of the 2,126,343 shares issued was $39,720 at the closing of the merger.
	In addition, there is contingent consideration related to an earnout provision that provides for the Company to pay Estech’s former shareholders up to $26,000 based on future performance of minimally invasive (MIS) sales, as defined by the merger agreement. The earnout calculation is based on the achievement of performance-based milestones. The earnout payment is a range of $3,000 to $13,000 upon the achievement of Combined MIS Revenue ranging from 90% to 125% of the 2014 Combined MIS Revenue Target or the 2015 Combined MIS Revenue Target. The Company has the option to make the payment related to the achievement of at least 90% of the 2014 Combined MIS Revenue Target or the 2015 Combined MIS Revenue Target in cash or through the issuance of AtriCure common stock. The other payments may only be made in cash. The fair value of the earnout calculation was estimated at acquisition using an expected present value approach to estimate an expected value, which, in statistical terms, is the weighted average of a discrete random variable’s possible values with the respective probabilities as the weights. The Company recorded $8,032 in contingent consideration at acquisition, and, based on current results, has reduced the value of the contingent consideration to $0 at December 31, 2014. The $8,032 adjustment was recorded as a reduction of selling, general and administrative expenses in the 2014 Consolidated Statement of Operations and Comprehensive Loss.
	The acquisition was accounted for in accordance with FASB ASC 805, “Accounting for Business Combinations” (ASC 805). The acquisition method of accounting was used to account for the acquisition, whereby the purchase price is required to be allocated to the underlying tangible and intangible assets acquired and liabilities assumed based on their respective fair market values. Any purchase price in excess of the fair market value of the acquired tangible and intangible assets is required to be allocated to goodwill. The process for estimating fair values of identifiable intangible assets and certain tangible assets and assumed liabilities requires the use of judgment in determining the appropriate assumptions and estimates. The judgments used to determine the estimated fair value assigned to each class of assets acquired and liabilities assumed, as well as asset lives, can materially impact the Company’s results of operations.
	The operating results of Estech are included in the Consolidated Statements of Operations and Comprehensive Loss beginning January 1, 2014. The Consolidated Balance Sheet as of December 31, 2013 reflects the acquisition of Estech.
	The following table summarizes the estimated fair values of the assets acquired and liabilities assumed on the acquisition date:


		December 31,
		2013
	Cash and cash equivalents	$	3,708
	Accounts receivable		2,378
	Inventories		2,156
	Other current assets		271
	Property and equipment, net		1,026
	Intangible assets, net		10,279
	Other assets		51

	Total identifiable assets	$	19,869

	Accounts payable	$	1,761
	Accrued liabilities		5,742

	Total liabilities assumed	$	7,503

	Net identifiable assets acquired	$	12,366
	Goodwill		35,386

	Total consideration	$	47,752

	The above estimated fair values of assets acquired and liabilities assumed are based on the information that was available as of the acquisition date to estimate the fair value of assets acquired and liabilities assumed. The Company believes that such information provides a reasonable basis for estimating the fair values. There were no significant changes to the purchase price allocation since the acquisition. None of the goodwill recorded in the acquisition is deductible for income tax purposes.
	The valuation of the intangible assets acquired and related amortization periods are as follows:


		Valuation			Amortization Term
		Valuation			(in years)
	Fusion technology	$	9,242			10
	Clamp and probe technology		829			3
	Estech trade name		208			1

	Total	$	10,279

	The fair value of the Fusion technology was estimated using an income approach. Under this method, an intangible asset’s fair value is equal to the present value of the incremental after-tax cash flows (excess earnings) attributable solely to the intangible asset over its remaining useful life. The Company believes that the level and timing of cash flows appropriately reflect market participant assumptions. The fair values of the clamp and probe technology and the Estech trade name were estimated using an income approach based on royalty savings. Under this method, the fair value is equal to the present value of after-tax royalty savings plus the present value of the tax amortization benefit attributable to the intangible assets over their useful lives. To calculate fair value, the Company used cash flows discounted at rates considered appropriate given the inherent risks associated with each type of intangible asset. The intangible assets are amortized over their useful lives using the straight-line method. (See Note 6—Intangible Assets and Goodwill.)
	The Company recognized $1,207 of Estech acquisition-related costs that were expensed during 2013. The costs consisted of $509 for bank fees and expenses and $698 for legal, audit, tax and other costs. Acquisition-related costs expensed during 2014 totaled $298 and consisted of audit, tax, legal and other expenses. These costs are included in selling, general and administrative expenses in the accompanying Consolidated Statements of Operations and Comprehensive Loss.
	As a result of the acquisition, the Company has performed certain transitional contractual obligations for an unrelated third party which were previously arranged by Estech. At December 31, 2014 the Company has recorded a receivable in the Consolidated Balance Sheet of $1,275 for amounts advanced on behalf of the third party. Substantially all transitional services are complete at December 31, 2014.
	The following supplemental pro forma information presents the financial results of the Company for the years ended December 31, 2013 and 2012 as if the acquisition of Estech had occurred on January 1, 2012. This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the acquisition been made on January 1, 2012, nor are they indicative of any future results.


		Year Ended
		December 31, (unaudited)
		2013			2012
	Revenue	$	93,846		$	81,954
	Net loss		(21,161	)		(19,031	)
	Basic and diluted net loss per share		(0.91	)		(1.04	)

	These amounts have been calculated after applying the Company’s accounting policies and adjusting the results of Estech to reflect factually supportable adjustments that give effect to events that are directly attributable to the Estech acquisition.

Intangible_Assets_and_Goodwill

Intangible Assets and Goodwill	12 Months Ended
Intangible Assets and Goodwill	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	6. INTANGIBLE ASSETS AND GOODWILL
	The following table provides a summary of the Company’s intangible assets with definite lives at December 31:


		2014				2013
		Cost		Accumulated		Cost		Accumulated
		Cost		Amortization		Cost		Amortization
	Non-compete agreement	$	100	$	93	$	100	$	80
	Fusion technology		9,242		924		9,242		—
	Clamp & probe technology		829		276		829		—
	Estech trade name		208		208		208		—

	Total	$	10,379	$	1,501	$	10,379	$	80

	For the years ended December 31, 2014, 2013 and 2012, amortization expense related to intangible assets with definite lives was $1,421, $12 and $13, respectively.
	Future amortization expense related to intangible assets with definite lives is projected as follows:


	2015	$	1,208
	2016		1,201
	2017		924
	2018		924
	2019		924
	2020 and thereafter		3,697

	Total	$	8,878

	The following table provides a summary of the Company’s goodwill, which is not amortized, but rather tested annually for impairment:


	Net carrying amount as of December 31, 2012	$	—
	Additions		35,386

	Net carrying amount as of December 31, 2013		35,386
	Adjustments		—

	Net carrying amount as of December 31, 2014	$	35,386

Inventories

Inventories	12 Months Ended
Inventories	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventories	7. INVENTORIES
	Inventories consisted of the following at December 31:


		2014		2013
	Raw materials	$	4,429	$	3,279
	Work in process		1,397		1,472
	Finished goods		8,431		5,463

	Inventories	$	14,257	$	10,214

Property_and_Equipment

Property and Equipment	12 Months Ended
Property and Equipment	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and Equipment	8. PROPERTY AND EQUIPMENT
	Property and equipment consisted of the following at December 31:


		2014			2013
	Generators and other capital equipment	$	8,578		$	6,896
	Machinery, equipment and vehicles		2,604			3,021
	Computer and other office equipment		2,436			1,522
	Furniture and fixtures		488			208
	Leasehold improvements		329			262
	Equipment under capital leases		162			153
	Construction in progress		4,642			411

	Total		19,239			12,473
	Less accumulated depreciation		(7,687	)		(6,830	)

	Property and equipment, net	$	11,552		$	5,643

	Property and equipment depreciation expense was $3,353, $2,008 and $1,886 for the years ended December 31, 2014, 2013 and 2012, respectively. Depreciation related to generators and other capital equipment was $2,172, $1,251 and $1,081 in 2014, 2013 and 2012, respectively. As of December 31, 2014 and 2013, the net carrying amount of this equipment was $4,141 and $3,173, respectively.
	Included in construction in progress as of December 31, 2014 are $4,234 of costs related to the construction of the Company’s new headquarters building (see Note 11—Commitments and Contingencies).

Accrued_Liabilities

Accrued Liabilities	12 Months Ended
Accrued Liabilities	Dec. 31, 2014
Payables and Accruals [Abstract]
Accrued Liabilities	9. ACCRUED LIABILITIES
	Accrued liabilities consisted of the following at December 31:


		2014		2013
	Accrued bonus	$	4,915	$	6,849
	Accrued commissions		4,477		3,827
	Accrued payroll and employee-related expenses		2,281		1,404
	Accrued taxes and value-added taxes payable		1,272		907
	Accrued royalties		442		307
	Other accrued liabilities		399		1,062
	Sales returns allowance		135		105
	Accrued non-employee stock options		120		350
	Accrued settlement reserve (current portion)		—		1,259

	Total	$	14,041	$	16,070

Indebtedness

Indebtedness	12 Months Ended
Indebtedness	Dec. 31, 2014
Debt Disclosure [Abstract]
Indebtedness	10. INDEBTEDNESS
	Long-term debt and capital leases consisted of the following at December 31:


		2014			2013
	Credit facility	$	—		$	6,333
	Capital leases		114			117

	Total debt and capital leases		114			6,450
	Less: Current maturities		(40	)		(2,038	)

	Total long-term debt and capital leases	$	74		$	4,412

	The Company first entered into a debt agreement with Silicon Valley Bank (SVB) on May 1, 2009. The agreement, as amended, restated and modified, includes a $15,000 revolving credit facility which matures on April 30, 2016. A $10,000 term loan was part of the Company’s debt agreement with SVB until it was repaid in full in March 2014. The Company recorded $37 of accelerated amortization expense related to deferred financing costs on the term loan in March 2014.
	Effective April 30, 2014 the Company and SVB entered into a Joinder and Seventh Loan Modification Agreement which set forth certain amendments to the Company’s revolving credit facility with the bank. Key changes in this Modification Agreement included: (i) extending the expiration to April 30, 2016, (ii) increasing the revolving credit facility to $15,000, (iii) reducing the unused revolving line facility fee, (iv) removing the Export-Import Bank of the United States portion of the facility, and (v) adding the Company’s wholly-owned subsidiary, Endoscopic Technologies, LLC, as a borrower.
	The debt agreement, as amended restated and modified, contains covenants that include, among others, covenants that limit the Company’s ability to dispose of assets, enter into mergers or acquisitions, incur indebtedness, incur liens, pay dividends or make distributions on the Company’s capital stock, make investments or loans, and enter into certain affiliate transactions, in each case subject to customary exceptions for a credit facility of this size and type. Additional covenants apply when the Company has outstanding borrowings under the revolving credit facility or when the Company holds less than $20,000 in cash and investments with SVB. Financial covenants under the credit facility include a minimum EBITDA and a minimum liquidity ratio. Further, a minimum fixed charge ratio applies when the Company achieves specific covenant milestones. None of the covenants must be applied as of December 31, 2014. The occurrence of an event of default could result in an increase to the applicable interest rate by 3.0%, an acceleration of all obligations under the Agreement, an obligation of the Company to repay all obligations in full and a right by SVB to exercise all remedies available to it under the Agreement and related agreements including the Guaranty and Security Agreement. Specified assets have been pledged as collateral.
	Borrowing availability under the revolving credit facility is based on the lesser of $15,000 or a borrowing base calculation as defined by the agreement. As of December 31, 2014 the Company had no borrowings under the revolving credit facility and borrowing availability of $12,383. As of December 31, 2014 the Company had an outstanding letter of credit of €75 issued to AtriCure Europe’s corporate credit card program provider which will expire on June 30, 2015.
	As of December 31, 2014 the Company had capital leases for computer equipment that expire at various terms through 2018. The cost of the assets under lease was $162. The assets are depreciated over their estimated useful lives, which equal the terms of the leases. Accumulated amortization on the capital leases was $59 at December 31, 2014.

	Future maturities on capital lease obligations are projected as follows:


	2015	$	45
	2016		44
	2017		24
	2018		10

	Total payments	$	123
	Imputed interest		(9	)

	Net capital lease obligations	$	114

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. COMMITMENTS AND CONTINGENCIES
	Lease Commitments. The Company leases various types of office, manufacturing and warehouse facilities and equipment under noncancelable operating leases that expire at various terms through 2021. Future minimum lease payments under non-cancelable operating leases are projected as follows:


	2015	$	839
	2016		240
	2017		172
	2018		174
	2019		171
	2020 and thereafter		140

	Total	$	1,736

	The table above does not include annual lease payments of approximately $1,400 related to a new headquarters building lease due to the uncertainty of the timing of lease inception.
	In August 2014 the Company and LM-VP AtriCure, LLC (Landlord), a third party unrelated to the Company, entered into a new building lease (Mason Lease) in order to re-locate its headquarters and West Chester, Ohio facilities from their current location to a building to be constructed on Innovation Way in Mason, Ohio and occupied exclusively by the Company.
	The term of the Mason Lease is fifteen years with three separate five-year renewal options, at the Company’s option, and begins upon substantial completion of the construction of the building (Commencement Date). The amount of initial annual base rent of $1,353 is payable monthly beginning on the Commencement Date and is subject to a 2% increase each year during the initial term of the agreement. Upon each renewal, the amount of rent payable will be agreed upon by the Company and Landlord or, if not so agreed upon, by an appraiser. The size of the building subject to the Mason Lease is expected to be approximately 92 square feet.
	Under the Mason Lease, the Company is responsible for paying real estate taxes, insurance, utilities, operating expenses, and most building repairs and maintenance. The Company is also responsible for paying the first $750 of construction related tenant improvement costs, as well as amounts in excess of the estimated total cost of construction, as defined by the Mason Lease. On the Commencement Date, the Company is required to provide 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 is deemed the owner of the project during the construction period. As a result, approximately $3,941 of project costs incurred to date to construct the building are included in property and equipment and the financing obligation is included in other current liabilities in the Consolidated Balance Sheet as of December 31, 2014. An increase in purchases of property and equipment and proceeds from the construction financing obligation were also included in the Consolidated Statement of Cash Flows as of December 31, 2014.
	Rent expense was approximately $1,331, $870 and $769 in 2014, 2013, and 2012, respectively.
	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 product sales. One of the agreements includes minimum quarterly payments of $50 through 2015 and a maximum of $2,000 in total royalties over the term of the agreement. Parties to the royalty agreements have the right at any time to terminate the agreement immediately for cause. Royalty expense of $1,322, $962 and $603 was recorded as part of cost of revenue for the years ended December 31, 2014, 2013 and 2012, respectively.
	Purchase Agreements. The Company enters into standard purchase agreements with certain vendors in the ordinary course of business. Outstanding commitments at December 31, 2014 were not significant.
	Chief Financial Officer and Chief Executive Officer Resignations. The Company’s Vice President, Finance and Administration and Chief Financial Officer (CFO) resigned effective April 30, 2012. In connection with the resignation, the CFO and AtriCure entered into an agreement pursuant to which the CFO is entitled to receive: (i) all accrued and unpaid base salary through the effective date of the resignation; (ii) payment for any accrued and unused vacation; (iii) continued vesting of all stock options and restricted stock until April 30, 2013; and (iv) twelve (12) months base salary ($250).
	On August 2, 2012, the Company’s Chief Executive Officer and President (CEO) notified the Company that he was resigning from his positions with the Company. Pursuant to his Employment Agreement, the CEO continued to serve as Chief Executive Officer and President of the Company through September 30, 2012. The CEO’s term as a member of the Company’s Board of Directors ended effective August 2, 2012. In connection with the resignation, the CEO and AtriCure entered into an agreement pursuant to which he is entitled to receive: (i) all accrued and unpaid base salary through the effective date of the resignation; (ii) payment for any accrued and unused vacation; (iii) continued vesting of all stock options and restricted stock until March 31, 2013; and (iv) six (6) months base salary ($225).
	The Company recorded a total of approximately $1,600 in expense related to the departure of the Company’s Chief Financial Officer and Chief Executive Officer during 2012.
	Legal. The Company is not party to any material pending or threatened litigation, except as described below:
	Department of Justice Investigation
	In October 2008 the Company received a letter from the Department of Justice (DOJ) informing the Company that it was conducting an investigation for potential False Claims Act (FCA) and common law violations relating to its surgical ablation devices. The Company cooperated with the investigation and operated its business in the ordinary course during the investigation. In December 2009 the Company reached a tentative settlement with the DOJ to resolve the investigation and recorded a liability. The settlement was finalized pursuant to the preliminary terms in February 2010, and the resulting settlement agreement definitively resolved all claims related to the DOJ investigation. The Company did not admit nor will it admit to any wrongdoing in connection with the settlement. As of December 31, 2014 the Company had completed making payments totaling $4,350 (including interest) and has no remaining financial liability.
	The Company may, from time to time, become a party to additional legal proceedings.

Income_Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	12. INCOME TAXES
	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 detail of deferred tax assets and liabilities at December 31 is as follows:


		2014			2013
	Deferred tax assets (liabilities):
	Net operating loss carryforward	$	49,921		$	46,362
	Research and development and AMT credit carryforwards, net		4,799			4,425
	Equity compensation		4,497			2,477
	Accruals and reserves		536			1,007
	Inventories		669			290
	Intangible assets		(149	)		(186	)
	Property and equipment, net		(760	)		(173	)
	Other, net		41			9

	Subtotal		59,554			54,211
	Less valuation allowance		(59,554	)		(54,211	)

	Total	$	—		$	—

	The Company’s provision for income taxes is as follows:


		2014			2013			2012
	Current income tax expense	$	33		$	18		$	50
	Deferred tax benefit		(5,306	)		(3,728	)		(2,336	)
	Increase in valuation allowance		5,306			3,728			2,336

	Total income tax expense	$	33		$	18		$	50

	The Company has a federal net operating loss carryforward of $129,976 which will begin to expire in 2019 and state net operating loss carryforwards of $71,4470 which have varying expirations ranging from five years to twenty years. At December 31, 2014 there were $3,873 of unrecognized deferred tax assets that arose from tax deductions for equity compensation in excess of compensation recognized for financial reporting during years when net operating losses were created. Additional paid in capital will be increased if such deferred tax assets are realized and reduce current tax payable. A portion of the Company’s federal and state net operating loss carryforwards are subject to certain limitations under Internal Revenue Code Sections 382 and 383. The Company also has a foreign net operating loss carryforward of approximately $14,098 which will begin to expire in 2016. Additionally, the Company has a federal research and development credit carryforward of $4,697 which will begin to expire in 2022.
	The Company’s 2014, 2013 and 2012 effective income tax rates differ from the federal statutory rate as follows:


		2014						2013						2012
	Federal tax at statutory rate		34	%	$	(5,501	)		34	%	$	(3,891	)		34	%	$	(2,483	)
	Federal R&D credit		2.32			(374	)		3.35			(383	)		0.08			(6	)
	Valuation allowance		(32.80	)		5,306			(29.63	)		3,391			(31.98	)		2,336
	State income taxes		2.68			(433	)		0.04			(5	)		0.67			(49	)
	Foreign NOL rate change		(4.29	)		694			2.47			(283	)		1.4			(102	)
	Foreign tax rate differential		(2.83	)		458			(1.60	)		183			(1.94	)		142
	Other		0.72			(117	)		(8.79	)		1,006			(2.91	)		212

	Effective tax rate		(0.20	)%	$	33			(0.16	)%	$	18			(0.68	)%	$	50

	The Company’s pre-tax book loss for domestic and international operations was ($11,085) and ($5,093), respectively, for 2014, ($9,409) and ($2,035), respectively, for 2013 and ($5,909) and ($1,575), respectively, for 2012.
	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 Consolidated Statements of Operations and Comprehensive Loss and within the related tax liability line in the Consolidated Balance Sheets.
	Federal, state, and local tax returns of the Company are routinely subject to examination by various taxing authorities. Federal and foreign income tax returns for periods beginning in 2011 are open for examination. However, taxing authorities have the ability to adjust net operating loss and tax credit carryforwards from years prior to these periods. The Company has not recognized certain tax benefits because of the uncertainty of realizing the entire value of the of the tax position taken on income tax returns upon review by the taxing authorities.
	A reconciliation of the change in federal and state unrecognized tax benefits for 2014, 2013, and 2012 is presented below:


		2014			2013			2012
	Balance at the beginning of the year	$	1,982		$	—		$	—
	Increases (decreases) for prior year tax positions		—			1,982			—
	Increases (decreases) for current year tax positions		—			—			—
	Increases (decreases) related to settlements		—			—			—
	Decreases related to statute lapse		—			—			—

	Balance at the end of the year	$	1,982		$	1,982		$	—


	There are no amounts included in the balance of unrecognized tax benefits at December 31, 2014, 2013 and 2012 that, if recognized, would affect the effective tax rate. Included in the balance of unrecognized tax benefits at December 31, 2014 are $1,982 of tax benefits that, if recognized, would result in adjustments to other tax accounts, primarily deferred taxes and valuation allowance. There are no accrued interest and penalties associated with the unrecognized tax benefit. The Company does not anticipate that there will be any significant adjustments to its recorded unrecognized tax benefits in the next twelve months.

Concentrations

Concentrations	12 Months Ended
Concentrations	Dec. 31, 2014
Risks and Uncertainties [Abstract]
Concentrations	13. CONCENTRATIONS
	During fiscal 2014, 2013 and 2012 approximately 13.6%, 20.4% and 19.6%, respectively, of the Company’s total net revenue was derived from its top ten customers. During 2014, 2013, and 2012 no individual customer accounted for more than 10% of the Company’s revenue. One customer accounted for approximately 8.7% and 11.5% of accounts receivable at December 31, 2014 and 2013, respectively.
	The Company maintains cash and cash equivalents balances at financial institutions which at times exceed FDIC limits. As of December 31, 2014 $28,457 of the cash and cash equivalents balance was in excess of the FDIC limits.

Employee_Benefit_Plans

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2014
Postemployment Benefits [Abstract]
Employee Benefit Plans	14. EMPLOYEE BENEFIT PLANS
Employee Benefit Plans	The Company sponsors the AtriCure, Inc. 401(k) Plan (401(k) Plan), a defined contribution plan covering substantially all U.S. employees of the Company. Eligible employees may contribute pre-tax annual compensation up to specified maximums under the Internal Revenue Code. During 2014 and 2013 the Company made matching contributions of 50% of the first 6% of employee contributions to the 401(k) Plan. During 2012 the Company made matching contributions of 25% of the first 6% of employee contributions to the 401(k) Plan. The Company’s matching contributions expensed during 2014, 2013 and 2012 were $807, $606 and $234, respectively. Additional amounts may be contributed to the 401(k) Plan at the discretion of the Company’s board of directors. No such discretionary contributions were made during 2014, 2013 or 2012. The Estech 401(k) plan acquired by the Company through its acquisition of Estech was rolled into the 401(k) Plan during 2014. The Company also provides retirement benefits for AtriCure Europe employees. Total contributions to retirement plans were $176, $176 and $114 in 2014, 2013 and 2012, respectively.

Equity_Compensation_Plans

Equity Compensation Plans	12 Months Ended
Equity Compensation Plans	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Compensation Plans	15. EQUITY COMPENSATION PLANS
	The Company has several share-based incentive plans: the 2001 Stock Option Plan (2001 Plan), 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).
	2001 Plan, 2005 Plan and 2014 Plan
	Neither the 2001 Plan nor the 2005 Plan is currently used for granting incentives. 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 exercise price of options, the number of shares subject to each award, the exercisability of the awards and the form of consideration.

	Options granted under the plans generally expire ten years from 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 vest 25% annually over four years from date of grant.
	As of December 31, 2014 8,949 shares of common stock had been reserved for issuance under the 2014 Plan. The shares authorized for issuance under the 2014 Plan include (a) shares reserved but unissued under the 2001 Plan as of August 10, 2005, (b) shares returned to the 2001 Plan as the result of the termination of options or the repurchase of shares issued under such plan, (c) shares reserved but unissued under the 2005 Plan as of May 14, 2014 and (d) 1,300 additional shares authorized under the 2014 Plan. As of December 31, 2014 there were 2,233 shares available for future grants under the plans.
	Activity under the plans during 2014 was as follows:


	Time-Based Stock Options		Number of				Weighted			Weighted			Aggregate
			Shares				Average			Average			Intrinsic
			Outstanding				Exercise			Remaining			Value
							Price			Contractual
										Term
	Outstanding at January 1, 2014			2,423			$	8.61
	Granted			603				19.54
	Cancelled or forfeited			(49	)			10.65
	Exercised			(215	)			8.94

	Outstanding at December 31, 2014			2,762			$	10.93			6.54		$	25,335

	Vested and expected to vest			2,660			$	10.81			6.46		$	24,697

	Exercisable at December 31, 2014			1,516			$	8.85			4.86		$	16,836


	Restricted Stock		Number of				Weighted
			Shares				Average
			Outstanding				Grant Date
							Fair Value
	Outstanding at January 1, 2014			248			$	7.75
	Awarded			391				20.25
	Forfeited			(1	)			9.15
	Released			(78	)			8.79

	Outstanding at December 31, 2014			560			$	16.33


	Performance Stock Options		Number of				Weighted			Weighted			Aggregate
			Shares				Average			Average			Intrinsic
			Outstanding				Exercise			Remaining			Value
							Price			Contractual
										Term
										(years)
	Outstanding at January 1, 2014			225			$	5.91
	Granted			225				21.04

	Outstanding at December 31, 2014			450			$	13.48			8.5		$	3,161

	Exercisable at December 31, 2014			250			$	13.48			8.5		$	1,756


	Activity under the plans during 2013 was as follows:


	Time-Based Stock Options		Number of				Weighted			Weighted			Aggregate
			Shares				Average			Average			Intrinsic
			Outstanding				Exercise			Remaining			Value
							Price			Contractual
										Term
	Outstanding at January 1, 2013			3,172			$	8.81
	Granted			451				9.01
	Cancelled or forfeited			(912	)			10.34
Exercised			(288	)			5.98

Outstanding at December 31, 2013			2,423			$	8.61			6.47		$	24,403

Vested and expected to vest			2,302			$	8.66			6.34		$	23,082

Exercisable at December 31, 2013			1,363			$	9.07			4.59		$	13,102


Restricted Stock		Number of				Weighted
		Shares				Average
		Outstanding				Grant Date
						Fair Value
Outstanding at January 1, 2013			504			$	7.93
Awarded			55				9.35
Forfeited			(184	)			8.2
Released			(127	)			8.49

Outstanding at December 31, 2013			248			$	7.75


Performance Stock Options		Number of				Weighted			Weighted			Aggregate
		Shares				Average			Average			Intrinsic
		Outstanding				Exercise			Remaining			Value
						Price			Contractual
									Term
									(years)
Outstanding at January 1, 2013			225			$	5.91
Granted			—				—

Outstanding at December 31, 2013			225			$	5.91			8.8		$	2,873

Exercisable at December 31, 2013			50			$	5.91			8.8		$	639

The total intrinsic value of options exercised during the years ended December 31, 2014, 2013 and 2012 was $2,311, $951 and $1,338, respectively. As a result of the Company’s tax position, no tax benefit was recognized related to the stock option exercises. For 2014, 2013 and 2012, $1,916, $1,718 and $659, respectively, in cash proceeds were included in the Company’s Consolidated Statements of Cash Flows as a result of the exercise of stock options. The total fair value of performance shares vested during 2014, 2013 and 2012 was $0, $0 and $99, respectively. The total fair value of restricted stock vested during 2014, 2013 and 2012 was $1,434, $1,442 and $1,292, respectively.
The exercise price per share of each option is equal to the fair market value of the underlying share on the date of grant. The Company issues registered shares of common stock to satisfy stock option exercises and restricted stock grants.

The Company recognized expense related to time-based stock options and restricted stock for 2014, 2013, and 2012 of $5,383, $2,489 and $3,211, respectively. As of December 31, 2014 there was $15,913 of unrecognized compensation costs related to non-vested stock option and restricted stock arrangements ($8,775 relating to stock options and $7,138 relating to restricted stock). This cost is expected to be recognized over a weighted-average period of 2.5 years for stock options and 2.7 years for restricted stock.
The Company awarded 225 performance options to its new President and Chief Executive Officer (CEO) when he joined the Company in November 2012, and an additional 225 performance options were awarded to the CEO in January 2014. The options expire ten years from the date of grant and vest in increments of 25 shares when the volume adjusted weighted average closing price of the common stock of the Company as reported by NASDAQ (or any other exchange on which the common stock of the Company is listed) for 30 consecutive days equals or exceeds each of $10.00 per share, $12.50 per share, $15.00 per share, $17.50 per share, $20.00 per share, $25.00 per share, $30.00 per share, $35.00 per share and $40.00 per share. In accordance with FASB ASC 718, a Monte Carlo simulation was performed for both grants to estimate the fair values, vesting terms and vesting probabilities for each tranche of options. Expense calculated using these estimates is being recorded over the estimated vesting terms. The Company recognized expense related to the performance options during 2014, 2013 and 2012 of $1,767, $272 and $36, respectively. As of December 31, 2014 there was $859 of unrecognized compensation costs related to non-vested performance options. This cost is expected to be recognized over a weighted-average period of 0.67 to 3.05 years.
In conjunction with the departure of the Company’s Chief Financial Officer on April 30, 2012, the Company extended the vesting terms of the share-based compensation of this former employee. This extension resulted in a modification per FASB ASC 718. As such, the Company recorded $396 in incremental compensation expense during the second quarter of 2012.
In conjunction with the departure of the Company’s Chief Executive Officer on September 30, 2012, the Company extended the vesting terms of the share-based compensation of this former employee. This extension resulted in a modification per FASB ASC 718. As such, the Company recorded $522 in incremental compensation expense during the third quarter of 2012.
Employee Stock Purchase Plan (ESPP)
During 2008 the Company established its 2008 Employee Stock Purchase Plan (ESPP) which 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 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 December 31, 2014, there were 578 shares available for future issuance under the ESPP. Share-based compensation expense with respect to the ESPP was $421, $319 and $257 for 2014, 2013, and 2012, respectively.

Valuation and Expense Information Under FASB ASC 718
The following table summarizes share-based compensation expense related to employee share-based compensation under FASB ASC 718 for 2014, 2013 and 2012. This expense was allocated as follows:


		2014				2013			2012
Cost of revenue		$	335			$	246		$	272
Research and development expenses			937				230			267
Selling, general and administrative expenses			6,299				2,604			2,929

Total		$	7,571			$	3,080		$	3,468

In calculating compensation expense, the fair value of the options is estimated on the grant date using the Black-Scholes model including the following assumptions:


		2014		2013		2012
Risk-free interest rate		1.56 – 2.12%		0.75 – 2.29%		0.65 – 1.37%
Expected life of option (years)		5.31 to 6.72		5.31 to 7.38		5.38 to 7.14
Expected volatility of stock		47.00 – 70.00%		69.00%		69.00 – 71.00%
Weighted-average volatility		69.19%		69.00%		69.50%
Dividend yield		0.00%		0.00%		0.00%
The Company’s estimate of volatility is based solely on the Company’s trading history. The risk-free interest rate assumption is based upon the U.S. treasury yield curve at the time of grant for the expected option life. The Company estimates the expected terms of options using historical employee exercise behavior.
The fair value of restricted stock awards is based on the market value of the Company’s stock on the date of the awards.
Based on the assumptions noted above, the weighted average estimated grant date fair value per share of the stock options and restricted stock granted for 2014, 2013 and 2012 was as follows:


		2014				2013			2012
Stock options		$	12.33			$	5.7		$	4.65
Restricted stock			20.25				9.35			7.69
In calculating compensation expense for performance options, the fair value of the options is estimated on the grant date using a Monte Carlo simulation including the following assumptions:


		2014		2013
Strike price		$5.91 – $21.04		$5.91
Contractual term (years)		10		10
Expected volatility of stock		60.50% – 69.60%		69.60%
Interest rate		1.75% – 2.73%		1.75%
Dividend yield		0.00%		0.00%
The contractual term assumes that the performance options issued to the CEO of the Company in 2012 and 2014 will be held until expiration. Expected volatility is estimated based on the Company’s trading history. The expected rate of return assumption is based upon the U.S. treasury yield curve at the time of grant for the expected option life.

Based on the assumptions noted above, the estimated grant date fair value per share of the performance options granted were as follows:


		Price Target				Fair Value of			Fair Value of
		Price Target				2012 Grant			2014 Grant
Tranche 1		$	10			$	4.32		$	14.74
Tranche 2			12.5				4.3			14.74
Tranche 3			15				4.27			14.74
Tranche 4			17.5				4.23			14.74
Tranche 5			20				4.19			14.73
Tranche 6			25				4.1			14.73
Tranche 7			30				4.01			14.71
Tranche 8			35				3.92			14.67
Tranche 9			40				3.83			14.61
Non-Employee Stock Compensation
Through 2008, the Company issued nonstatutory common stock options to consultants to purchase shares of common stock as a form of compensation for services provided to the Company. Such options vested over a service period ranging from immediately to four years. After January 1, 2006 all stock options granted to non-employee consultants had a four year vesting period and vested at a rate of 25% on the first anniversary date of the grant and ratably each month thereafter.
The Company accounted for the options granted to non-employees prior to their vesting date in accordance with ASC 505-50. Because these options did not contain specific performance provisions, there was no measurement date of fair value until the options vested. Therefore, the fair value of the options granted and outstanding prior to their vesting date was remeasured each reporting period. The fair value was determined using the Black-Scholes model. The values attributable to the unvested portion of the non-employee stock options were amortized over the service period on a graded vesting method, and the vested portion of these stock options was remeasured at each vesting date. As of December 31, 2014 all non-employee consultant options were fully vested.
Once these non-employee consultant stock options have vested, the awards no longer fall within the scope of ASC 505-50. Because the stock options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the award agreements allow the stock options to be partially net-cash settled, these vested stock options are no longer eligible for equity classification and are, thus, accounted for as derivative liabilities under FASB ASC 815 until the stock options are ultimately either exercised or forfeited. Accordingly, the vested non-employee consultant stock options are classified as liabilities and remeasured at fair value through earnings at each reporting period. During 2014, 2013 and 2012, ($183), $272 and ($179), respectively, of (income) expense was recorded as a result of the remeasurement of the fair value of these stock options. As of December 31, 2014 and 2013, fully vested stock options to acquire 20 and 38 shares of common stock held by non-employee consultants remained unexercised and a liability of $120 and $350 was included in accrued liabilities in the Consolidated Balance Sheets as of December 31, 2014 and December 31, 2013, respectively.

Segment_and_Geographic_Informa

Segment and Geographic Information	12 Months Ended
Segment and Geographic Information	Dec. 31, 2014
Segment Reporting [Abstract]
Segment and Geographic Information	16. 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 for the treatment of atrial fibrillation 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.
	Domestic revenue by product type was as follows:


	Revenue:	2014		2013		2012
	Open-heart	$	44,662	$	37,843	$	32,880
	Minimally invasive		16,050		13,648		12,733
	AtriClip		16,675		10,820		7,003
	Valve tools		2,816		—		—

	Total domestic	$	80,203	$	62,311	$	52,616

	International revenue by product type was as follows:


	Revenue:	2014		2013		2012
	Open-heart	$	16,445	$	13,064	$	11,972
	Minimally invasive		7,881		5,354		4,813
	AtriClip		2,158		1,160		846
	Valve tools		767		—		—

	Total international	$	27,251	$	19,578	$	17,631

	Revenue by geographic area, classified based on the country location of the customer, was as follows:


	Revenue:	2014		2013		2012
	United States	$	80,203	$	62,311	$	52,616
	Europe		18,163		11,384		10,344
	Asia		8,552		7,665		6,730
	Other international		536		529		557

	Total revenue	$	107,454	$	81,889	$	70,247

	The majority of the Company’s long-lived assets are located in the United States.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
Selected Quarterly Financial Data (Unaudited)	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	17. SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)


		For the Three Months Ended
		March 31,						June 30,						September 30,						December 31,
		2014			2013			2014			2013			2014			2013			2014			2013
	Operating Results:
	Revenue	$	24,847		$	19,430		$	26,514		$	20,429		$	26,678		$	20,146		$	29,415		$	21,884
	Gross profit		17,657			14,086			18,781			15,123			18,892			14,685			20,420			15,669
	Loss from operations		(7,925	)		(1,800	)		(2,853	)		(1,639	)		(803	)		(2,614	)		(4,779	)		(4,838	)
	Net loss		(7,709	)		(1,943	)		(2,692	)		(1,791	)		(466	)		(2,748	)		(5,344	)		(4,980	)
	Net loss per share (basic and diluted)	$	(0.31	)	$	(0.10	)	$	(0.10	)	$	(0.09	)	$	(0.02	)	$	(0.13	)	$	(0.20	)	$	(0.24	)
	Amounts may not sum to consolidated totals for the full year due to rounding. Basic and diluted net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per share amounts will not necessarily equal the total for the year.

Valuation_and_Qualifying_Accou

Valuation and Qualifying Accounts	12 Months Ended
Valuation and Qualifying Accounts	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	SCHEDULE II
	VALUATION AND QUALIFYING ACCOUNTS


		Beginning		Additions		Deductions		Ending
		Balance		Additions		Deductions		Balance

	Allowancefor doubtful accounts receivable
	Year ended December 31, 2014	$	94	$	84	$	110	$	68
	Year ended December 31, 2013		49		100		55		94
	Year ended December 31, 2012		37		75		63		49

	Reserve for sales returns and allowances
	Year ended December 31, 2014	$	105	$	34	$	4	$	135
	Year ended December 31, 2013		105		—		—		105
	Year ended December 31, 2012		40		262		197		105

	Allowance for inventory valuation
	Year ended December 31, 2014	$	782	$	441	$	701	$	522
	Year ended December 31, 2013		267		921		406		782
	Year ended December 31, 2012		206		381		320		267

	Valuation allowance for deferred tax assets
	Year ended December 31, 2014	$	54,211	$	5,343	$	—	$	59,554
	Year ended December 31, 2013		31,685		22,526		—		54,211
	Year ended December 31, 2012		29,316		2,369		—		31,685

Description_of_Business_and_Su1

Description of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
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 an innovator in surgical treatments for atrial fibrillation (Afib) and left atrial appendage management (LAAM). The Company sells its products to medical centers globally through a direct sales force and distributors.
Principles of Consolidation	Principles of Consolidation—The Consolidated Financial Statements include the accounts of the Company, AtriCure, LLC, the Company’s wholly-owned subsidiary organized in the State of Delaware, Endoscopic Technologies, LLC, the Company’s wholly-owned subsidiary 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 Consolidated Financial Statements. Money market funds are included in cash and cash equivalents.
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 to 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 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 $952, $786 and $723 in 2014, 2013 and 2012, 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.
Sales Returns and Allowances	Sales Returns and Allowances—While the Company’s products do not have return rights, 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 price adjustments. The Company estimates such provision quarterly based primarily on a specific identification basis, in addition to estimating a general reserve. Increases to the provision result in a reduction of revenue. The provision is included in accrued liabilities in the Consolidated Balance Sheets.
Allowance for Doubtful Accounts Receivable	Allowance for Uncollectible Accounts Receivable—The Company evaluates the collectability of accounts receivable in order 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 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) and 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 reserve 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. Write-offs are recorded when a product is destroyed. The Company’s history of write-offs against the reserve has not been significant.
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 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 useful lives of property and equipment annually, and assets are retired if they are no longer being used. Maintenance and repair costs are expensed as incurred.
	Generators and other capital equipment (such as the Company’s switchbox units and cryosurgical consoles) are loaned at no cost to 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.
	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. The Company’s amortization term for a non-compete agreement is eight years. Fusion technology is being amortized over ten years. Clamp and probe technology is being amortized over three years. The Estech trade name was amortized over one year. 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 uses readily available market information and income valuation approaches to estimate the fair value of the reporting unit. The income valuation approach is developed using the Company’s best estimates based on reasonable and supportable assumptions and projections. The Company’s goodwill is accounted for in a single reporting unit representing the Company as a whole.
Other Income	Other Income (Loss)—Other income (loss) consists primarily of foreign currency transaction gains and losses, grant income and non-employee option gains and losses related to the fair market value change for fully vested options outstanding for consultants which are accounted for as free-standing derivatives.
	The Company recorded foreign currency transaction (losses) gains of ($523), $269 and ($83) for the years ended December 31, 2014, 2013 and 2012, respectively, primarily in connection with settlements of its intercompany balances with AtriCure Europe.
	The Company periodically is awarded grants to support research and development or education activities. The Company recognizes grant income when the funds are earned. The Company recorded grant income of $731, $0 and $409 during 2014, 2013 and 2012, respectively.
	The Company historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. Because the non-employee options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the options to be partially net-cash settled, these options, when vested, are no longer eligible for equity classification and are, thus, subsequently accounted for as derivative liabilities under FASB ASC 815, “Derivatives and Hedging” (ASC 815) until the awards are ultimately either exercised or forfeited. Accordingly, the vested non-employee options are classified as liabilities and remeasured at fair value through earnings at each reporting period. During the years ended December 31, 2014, 2013 and 2012, ($183), $272 and ($179), respectively, of (income) expense was recorded as a result of the remeasurement of the fair value of these fully vested stock options.
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 (Affordable Care Act), required manufacturers of medical devices to pay an excise tax on all U.S. medical device sales beginning in January 2013. The Company’s expense related to the medical device excise tax, which was recorded in cost of revenue, was $592 and $417 for the years ended December 31, 2014 and 2013, 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 3,772, 2,721 and 3,676 stock options, restricted stock and performance-based shares as of December 31, 2014, 2013, and 2012, 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 Income (Loss)	Comprehensive Loss and Accumulated Other Comprehensive Income (Loss)—In addition to net loss, comprehensive loss includes foreign currency exchange rate adjustments and unrealized gains and losses on investments.
	Accumulated other comprehensive income (loss) consists of the following:


		2014			2013			2012
	Total accumulated other comprehensive income (loss) at beginning of period	$	(139	)	$	77		$	(37	)

	Unrealized (losses) gains on investments
	Balance at beginning of period	$	(6	)	$	1		$	2
	Other comprehensive loss before reclassifications		(48	)		(7	)		(1	)
	Amounts reclassified from accumulated other comprehensive income (loss) to other income		—			—			—

	Balance at end of period	$	(54	)	$	(6	)	$	1


	Foreign currency translation adjustment
	Balance at beginning of period	$	133		$	76		$	(39	)
	Other comprehensive income (loss) before reclassifications		362			(478	)		198
	Amounts reclassified from accumulated other comprehensive income (loss) to other income		(523	)		269			(83	)

	Balance at end of period	$	(294	)	$	(133	)	$	76


	Total accumulated other comprehensive (loss) income at end of period	$	(348	)	$	(139	)	$	77

Research and Development	Research and Development Costs—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 years ended December 31, 2014, 2013 and 2012, respectively.
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, performance shares 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 years ended December 31, 2014, 2013 and 2012 was $7,571, $3,080 and $3,468, respectively, on a before and after tax basis.
	FASB 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 Consolidated Statement of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures. FASB 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.
	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 vest.
	The Company also has an employee stock purchase plan (ESPP or Plan) which is available to all eligible employees as defined by the Plan. 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 Plan at the beginning of each purchase period. Compensation expense based upon the fair value of the stock at the beginning of the purchase period calculated using the Black-Scholes model is recognized over each purchase period.
	Also included in share-based compensation are stock options the Company has historically issued to non-employee consultants as a form of compensation for services provided to the Company. These options are accounted for as derivative liabilities under FASB ASC 815 until the stock options are ultimately either exercised or forfeited. Accordingly, the vested non-employee consultant stock options are classified as liabilities and remeasured at fair value through earnings at each reporting period (see Note 3—Fair Value and Note 15—Equity Compensation Plans for further information).
Use of Estimates	Use of Estimates—The preparation of the financial statements in conformity with accounting principles generally accepted in the United States of America (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 short-term 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 expenses 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. Other assets and other liabilities are classified as Level 1 within the fair value hierarchy. Cash equivalents and short-term investments in commercial paper 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 non-employee stock options are developed using Company data. When an input is changed, the Black-Scholes model is updated and the results are analyzed for reasonableness. Significant unobservable inputs with respect to the fair value measurement of the Level 3 acquisition-related contingent consideration are developed using Company data. When an input is changed, the expected present value calculation is updated and the results are analyzed for reasonableness.
Other Current Liabilities and Current Maturities of Debt and Capital Leases	Other Current Liabilities and Current Maturities of Debt and Capital Leases—Other current liabilities consists of a financing obligation related to the construction of the Company’s new headquarters (see Note 11 – Commitments and Contingencies). Current maturities of debt and capital leases consist of debt and capital lease obligations with maturities of less than one year (see Note 10 – Indebtedness).

Description_of_Business_and_Su2

Description of Business and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated other comprehensive income (loss) consists of the following:



		2014			2013			2012
	Total accumulated other comprehensive income (loss) at beginning of period	$	(139	)	$	77		$	(37	)
	Unrealized (losses) gains on investments
	Balance at beginning of period	$	(6	)	$	1		$	2
	Other comprehensive loss before reclassifications		(48	)		(7	)		(1	)
	Amounts reclassified from accumulated other comprehensive income (loss) to other income		—			—			—

	Balance at end of period	$	(54	)	$	(6	)	$	1


	Foreign currency translation adjustment
	Balance at beginning of period	$	(133	)	$	76		$	(39	)
	Other comprehensive income (loss) before reclassifications		362			(478	)		198
	Amounts reclassified from accumulated other comprehensive income (loss) to other income		(523	)		269			(83	)

	Balance at end of period	$	(294	)	$	(133	)	$	76

	Total accumulated other comprehensive (loss) income at end of period	$	(348	)	$	(139	)	$	77

Fair_Value_Tables

Fair Value (Tables)	12 Months Ended
Fair Value (Tables)	Dec. 31, 2014
Fair Value Disclosures [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 December 31, 2014:



		Quoted Prices in			Significant Other		Significant Other			Total
		Active Markets for			Observable Inputs		Unobservable
		Identical Assets			(Level 2)		Inputs
		(Level 1)					(Level 3)
	Assets:
	Money market funds	$	—		$	23,692	$	—		$	23,692
	Commercial paper		—			1,800		—			1,800
	U.S. government agencies and securities		3,022			—		—			3,022
	Corporate bonds		—			35,337		—			35,337

	Total assets	$	3,022		$	60,829	$	—		$	63,851

	Liabilities:
	Derivative instruments	$	—		$	—	$	120		$	120
	Acquisition-related contingent consideration		—			—		—			—

	Total liabilities	$	—		$	—	$	120		$	120


	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, 2013:



		Quoted Prices in			Significant Other		Significant Other			Total
		Active Markets for			Observable Inputs		Unobservable
		Identical Assets			(Level 2)		Inputs
		(Level 1)					(Level 3)
	Assets:
	Money market funds	$	—		$	4,295	$	—		$	4,295
	Commercial paper		—			2,598		—			2,598
	U.S. government agencies and securities		4,145			—		—			4,145
	Corporate bonds		—			12,490		—			12,490

	Total assets	$	4,145		$	19,383	$	—		$	23,528

	Liabilities:
	Derivative instruments	$	—		$	—	$	350		$	350
	Acquisition-related contingent consideration		—			—		8,032			8,032

	Total liabilities	$	—		$	—	$	8,382		$	8,382

Assumptions Used for Estimating Fair Value of Level 3 Derivative Instruments	The fair value of the Level 3 derivative instruments is estimated using the Black-Scholes model including the following assumptions:



		As of December 31, 2014		As of December 31, 2013
	Risk-free interest rate	0.07%		0.11% - 1.32%
	Expected life of option (years)	0.7		0.75 - 4.10
	Expected volatility of stock	39.91%		70.00%
	Dividend yield	0.00%		0.00%
Level 3 Fair Value Measurements Using Significant Other Unobservable Inputs for Derivative Instruments	The following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for derivative instruments as of December 31:



		2014			2013		2012
	Beginning Balance—January 1	$	350		$	78	$	208
	Total (gains) losses included in earnings		(183	)		272		(179	)
	Exercises		(47	)		—		(50	)
	Reclassification from equity to liability when fully vested		—			—		99

	Ending Balance—December 31	$	120		$	350	$	78

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 December 31:



		2014			2013		2012
	Beginning Balance—January 1	$	8,032		$	—	$	—
	Amounts acquired		—			8,032		—
	Transfers in (out) of Level 3		—			—		—
	Changes in fair value included in earnings		(8,032	)		—		—

	Ending Balance—December 31	$	—		$	8,032	$	—

Investments_Tables

Investments (Tables)	12 Months Ended
Investments (Tables)	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Summary of Short-term Investments	Investments as of December 31, 2014 consisted of the following:


		Cost Basis		Unrealized			Fair Value
		Cost Basis		Gains (Losses)			Fair Value
	Corporate bonds	$	35,389	$	(52	)	$	35,337
	U.S. government agencies and securities		3,024		(2	)		3,022
	Commercial paper		1,800		—			1,800

	Total	$	40,213	$	(54	)	$	40,159

	Investments as of December 31, 2013 consisted of the following:


		Cost Basis		Unrealized			Fair Value
		Cost Basis		Gains (Losses)			Fair Value
	Corporate bonds	$	12,498	$	(8	)	$	12,490
	U.S. government agencies and securities		4,143		2			4,145
	Commercial paper		2,598		—			2,598

	Total	$	19,239	$	(6	)	$	19,233

Business_Combination_Tables

Business Combination (Tables)	12 Months Ended
Business Combination (Tables)	Dec. 31, 2014
Business Combinations [Abstract]
Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed	The following table summarizes the estimated fair values of the assets acquired and liabilities assumed on the acquisition date:


		December 31,
		2013
	Cash and cash equivalents	$	3,708
	Accounts receivable		2,378
	Inventories		2,156
	Other current assets		271
	Property and equipment, net		1,026
	Intangible assets, net		10,279
	Other assets		51

	Total identifiable assets	$	19,869

	Accounts payable	$	1,761
	Accrued liabilities		5,742

	Total liabilities assumed	$	7,503

	Net identifiable assets acquired	$	12,366
	Goodwill		35,386

	Total consideration	$	47,752

Valuation of Intangible Assets Acquired and Related Amortization Periods	The valuation of the intangible assets acquired and related amortization periods are as follows:


		Valuation			Amortization Term
		Valuation			(in years)
	Fusion technology	$	9,242			10
	Clamp and probe technology		829			3
	Estech trade name		208			1

	Total	$	10,279

Pro-forma Acquisition Information	The following supplemental pro forma information presents the financial results of the Company for the years ended December 31, 2013 and 2012 as if the acquisition of Estech had occurred on January 1, 2012. This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the acquisition been made on January 1, 2012, nor are they indicative of any future results.


		Year Ended
		December 31, (unaudited)
		2013			2012
	Revenue	$	93,846		$	81,954
	Net loss		(21,161	)		(19,031	)
	Basic and diluted net loss per share		(0.91	)		(1.04	)

Intangible_Assets_and_Goodwill1

Intangible Assets and Goodwill (Tables)	12 Months Ended
Intangible Assets and Goodwill (Tables)	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Company's Intangible Assets with Definite Lives	The following table provides a summary of the Company’s intangible assets with definite lives at December 31:


		2014				2013
		Cost		Accumulated		Cost		Accumulated
		Cost		Amortization		Cost		Amortization
	Non-compete agreement	$	100	$	93	$	100	$	80
	Fusion technology		9,242		924		9,242		—
	Clamp & probe technology		829		276		829		—
	Estech trade name		208		208		208		—

	Total	$	10,379	$	1,501	$	10,379	$	80

Future Amortization Expense Related to Intangible Assets with Definite Lives	Future amortization expense related to intangible assets with definite lives is projected as follows:


	2015	$	1,208
	2016		1,201
	2017		924
	2018		924
	2019		924
	2020 and thereafter		3,697

	Total	$	8,878

Summary of Company's Goodwill	The following table provides a summary of the Company’s goodwill, which is not amortized, but rather tested annually for impairment:


	Net carrying amount as of December 31, 2012	$	—
	Additions		35,386

	Net carrying amount as of December 31, 2013		35,386
	Adjustments		—

	Net carrying amount as of December 31, 2014	$	35,386

Inventories_Tables

Inventories (Tables)	12 Months Ended
Inventories (Tables)	Dec. 31, 2014
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories consisted of the following at December 31:


		2014		2013
	Raw materials	$	4,429	$	3,279
	Work in process		1,397		1,472
	Finished goods		8,431		5,463

	Inventories	$	14,257	$	10,214

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
Property and Equipment (Tables)	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consisted of the following at December 31:


		2014			2013
	Generators and other capital equipment	$	8,578		$	6,896
	Machinery, equipment and vehicles		2,604			3,021
	Computer and other office equipment		2,436			1,522
	Furniture and fixtures		488			208
	Leasehold improvements		329			262
	Equipment under capital leases		162			153
	Construction in progress		4,642			411

	Total		19,239			12,473
	Less accumulated depreciation		(7,687	)		(6,830	)

	Property and equipment, net	$	11,552		$	5,643

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	12 Months Ended
Accrued Liabilities (Tables)	Dec. 31, 2014
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued liabilities consisted of the following at December 31:


		2014		2013
	Accrued bonus	$	4,915	$	6,849
	Accrued commissions		4,477		3,827
	Accrued payroll and employee-related expenses		2,281		1,404
	Accrued taxes and value-added taxes payable		1,272		907
	Accrued royalties		442		307
	Other accrued liabilities		399		1,062
	Sales returns allowance		135		105
	Accrued non-employee stock options		120		350
	Accrued settlement reserve (current portion)		—		1,259

	Total	$	14,041	$	16,070

Indebtedness_Tables

Indebtedness (Tables)	12 Months Ended
Indebtedness (Tables)	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-Term Debt and Capital Leases	Long-term debt and capital leases consisted of the following at December 31:


		2014			2013
	Credit facility	$	—		$	6,333
	Capital leases		114			117

	Total debt and capital leases		114			6,450
	Less: Current maturities		(40	)		(2,038	)

	Total long-term debt and capital leases	$	74		$	4,412

Future Maturities on Debt, Including Capital Lease Obligations	Future maturities on capital lease obligations are projected as follows:


	2015	$	45
	2016		44
	2017		24
	2018		10

	Total payments	$	123
	Imputed interest		(9	)

	Net capital lease obligations	$	114

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Lease Payments Under Non-cancellable Operating Leases	Future minimum lease payments under non-cancelable operating leases are projected as follows:


	2015	$	839
	2016		240
	2017		172
	2018		174
	2019		171
	2020 and thereafter		140

	Total	$	1,736

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Detail of Deferred Tax Assets and Liabilities	The detail of deferred tax assets and liabilities at December 31 is as follows:


		2014			2013
	Deferred tax assets (liabilities):
	Net operating loss carryforward	$	49,921		$	46,362
	Research and development and AMT credit carryforwards, net		4,799			4,425
	Equity compensation		4,497			2,477
	Accruals and reserves		536			1,007
	Inventories		669			290
	Intangible assets		(149	)		(186	)
	Property and equipment, net		(760	)		(173	)
	Other, net		41			9

	Subtotal		59,554			54,211
	Less valuation allowance		(59,554	)		(54,211	)

	Total	$	—		$	—
Company's Provision for Income Taxes	The Company’s provision for income taxes is as follows:


		2014			2013			2012
	Current income tax expense	$	33		$	18		$	50
	Deferred tax benefit		(5,306	)		(3,728	)		(2,336	)
	Increase in valuation allowance		5,306			3,728			2,336

	Total income tax expense	$	33		$	18		$	50

Difference Between Effective Income Tax Rates and Federal Statutory Rate	The Company’s 2014, 2013 and 2012 effective income tax rates differ from the federal statutory rate as follows:


		2014						2013						2012
	Federal tax at statutory rate		34	%	$	(5,501	)		34	%	$	(3,891	)		34	%	$	(2,483	)
	Federal R&D credit		2.32			(374	)		3.35			(383	)		0.08			(6	)
	Valuation allowance		(32.80	)		5,306			(29.63	)		3,391			(31.98	)		2,336
	State income taxes		2.68			(433	)		0.04			(5	)		0.67			(49	)
	Foreign NOL rate change		(4.29	)		694			2.47			(283	)		1.4			(102	)
	Foreign tax rate differential		(2.83	)		458			(1.60	)		183			(1.94	)		142
	Other		0.72			(117	)		(8.79	)		1,006			(2.91	)		212

	Effective tax rate		(0.20	)%	$	33			(0.16	)%	$	18			(0.68	)%	$	50

Reconciliation of Change in Federal and State Unrecognized Tax Benefits	A reconciliation of the change in federal and state unrecognized tax benefits for 2014, 2013, and 2012 is presented below:


		2014			2013			2012
	Balance at the beginning of the year	$	1,982		$	—		$	—
	Increases (decreases) for prior year tax positions		—			1,982			—
	Increases (decreases) for current year tax positions		—			—			—
	Increases (decreases) related to settlements		—			—			—
	Decreases related to statute lapse		—			—			—

	Balance at the end of the year	$	1,982		$	1,982		$	—

Equity_Compensation_Plans_Tabl

Equity Compensation Plans (Tables)	12 Months Ended
Equity Compensation Plans (Tables)	Dec. 31, 2014
Activity Under Stock Based Compensation Plans	Activity under the plans during 2014 was as follows:


	Time-Based Stock Options		Number of				Weighted			Weighted			Aggregate
			Shares				Average			Average			Intrinsic
			Outstanding				Exercise			Remaining			Value
							Price			Contractual
										Term
	Outstanding at January 1, 2014			2,423			$	8.61
	Granted			603				19.54
	Cancelled or forfeited			(49	)			10.65
	Exercised			(215	)			8.94

	Outstanding at December 31, 2014			2,762			$	10.93			6.54		$	25,335

	Vested and expected to vest			2,660			$	10.81			6.46		$	24,697

	Exercisable at December 31, 2014			1,516			$	8.85			4.86		$	16,836


	Restricted Stock		Number of				Weighted
			Shares				Average
			Outstanding				Grant Date
							Fair Value
	Outstanding at January 1, 2014			248			$	7.75
	Awarded			391				20.25
	Forfeited			(1	)			9.15
	Released			(78	)			8.79

	Outstanding at December 31, 2014			560			$	16.33


	Performance Stock Options		Number of				Weighted			Weighted			Aggregate
			Shares				Average			Average			Intrinsic
			Outstanding				Exercise			Remaining			Value
							Price			Contractual
										Term
										(years)
	Outstanding at January 1, 2014			225			$	5.91
	Granted			225				21.04

	Outstanding at December 31, 2014			450			$	13.48			8.5		$	3,161

	Exercisable at December 31, 2014			250			$	13.48			8.5		$	1,756


	Activity under the plans during 2013 was as follows:


	Time-Based Stock Options		Number of				Weighted			Weighted			Aggregate
			Shares				Average			Average			Intrinsic
			Outstanding				Exercise			Remaining			Value
							Price			Contractual
										Term
	Outstanding at January 1, 2013			3,172			$	8.81
	Granted			451				9.01
	Cancelled or forfeited			(912	)			10.34
	Exercised			(288	)			5.98

	Outstanding at December 31, 2013			2,423			$	8.61			6.47		$	24,403

	Vested and expected to vest			2,302			$	8.66			6.34		$	23,082

	Exercisable at December 31, 2013			1,363			$	9.07			4.59		$	13,102


Restricted Stock		Number of				Weighted
		Shares				Average
		Outstanding				Grant Date
						Fair Value
Outstanding at January 1, 2013			504			$	7.93
Awarded			55				9.35
Forfeited			(184	)			8.2
Released			(127	)			8.49

Outstanding at December 31, 2013			248			$	7.75


Performance Stock Options		Number of				Weighted			Weighted			Aggregate
		Shares				Average			Average			Intrinsic
		Outstanding				Exercise			Remaining			Value
						Price			Contractual
									Term
									(years)
Outstanding at January 1, 2013			225			$	5.91
Granted			—				—

Outstanding at December 31, 2013			225			$	5.91			8.8		$	2,873

Exercisable at December 31, 2013			50			$	5.91			8.8		$	639

Summary of Share-Based Compensation Expense Related to Employee Share-Based Compensation	The following table summarizes share-based compensation expense related to employee share-based compensation under FASB ASC 718 for 2014, 2013 and 2012. This expense was allocated as follows:


			2014				2013			2012
	Cost of revenue		$	335			$	246		$	272
	Research and development expenses			937				230			267
	Selling, general and administrative expenses			6,299				2,604			2,929

	Total		$	7,571			$	3,080		$	3,468

Assumptions Used for Determining Fair Value of Options	In calculating compensation expense, the fair value of the options is estimated on the grant date using the Black-Scholes model including the following assumptions:


			2014		2013		2012
	Risk-free interest rate		1.56 – 2.12%		0.75 – 2.29%		0.65 – 1.37%
	Expected life of option (years)		5.31 to 6.72		5.31 to 7.38		5.38 to 7.14
	Expected volatility of stock		47.00 – 70.00%		69.00%		69.00 – 71.00%
	Weighted-average volatility		69.19%		69.00%		69.50%
	Dividend yield		0.00%		0.00%		0.00%
Weighted Average Estimated Grant Date Fair Value Per Share of Stock Options and Restricted Stock Granted	Based on the assumptions noted above, the weighted average estimated grant date fair value per share of the stock options and restricted stock granted for 2014, 2013 and 2012 was as follows:


			2014				2013			2012
	Stock options		$	12.33			$	5.7		$	4.65
	Restricted stock			20.25				9.35			7.69
Estimated Grant Date Fair Value Per Share of Performance Options Granted	Based on the assumptions noted above, the estimated grant date fair value per share of the performance options granted were as follows:


			Price Target				Fair Value of			Fair Value of
			Price Target				2012 Grant			2014 Grant
	Tranche 1		$	10			$	4.32		$	14.74
	Tranche 2			12.5				4.3			14.74
	Tranche 3			15				4.27			14.74
	Tranche 4			17.5				4.23			14.74
	Tranche 5			20				4.19			14.73
	Tranche 6			25				4.1			14.73
	Tranche 7			30				4.01			14.71
	Tranche 8			35				3.92			14.67
	Tranche 9			40				3.83			14.61
Performance Shares [Member]
Assumptions Used for Determining Fair Value of Options	In calculating compensation expense for performance options, the fair value of the options is estimated on the grant date using a Monte Carlo simulation including the following assumptions:


			2014		2013
	Strike price		$5.91 – $21.04		$5.91
	Contractual term (years)		10		10
	Expected volatility of stock		60.50% – 69.60%		69.60%
	Interest rate		1.75% – 2.73%		1.75%
	Dividend yield		0.00%		0.00%

Segment_and_Geographic_Informa1

Segment and Geographic Information (Tables)	12 Months Ended
Segment and Geographic Information (Tables)	Dec. 31, 2014
Segment Reporting [Abstract]
Revenue by Product	Domestic revenue by product type was as follows:


	Revenue:	2014		2013		2012
	Open-heart	$	44,662	$	37,843	$	32,880
	Minimally invasive		16,050		13,648		12,733
	AtriClip		16,675		10,820		7,003
	Valve tools		2,816		—		—

	Total domestic	$	80,203	$	62,311	$	52,616

	International revenue by product type was as follows:


	Revenue:	2014		2013		2012
	Open-heart	$	16,445	$	13,064	$	11,972
	Minimally invasive		7,881		5,354		4,813
	AtriClip		2,158		1,160		846
	Valve tools		767		—		—

	Total international	$	27,251	$	19,578	$	17,631

Summary of Revenue by Geographic Area Classified Based on Country Location of Customer	Revenue by geographic area, classified based on the country location of the customer, was as follows:


	Revenue:	2014		2013		2012
	United States	$	80,203	$	62,311	$	52,616
	Europe		18,163		11,384		10,344
	Asia		8,552		7,665		6,730
	Other international		536		529		557

	Total revenue	$	107,454	$	81,889	$	70,247

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
Selected Quarterly Financial Data (Unaudited) (Tables)	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information
		For the Three Months Ended
		March 31,						June 30,						September 30,						December 31,
		2014			2013			2014			2013			2014			2013			2014			2013
	Operating Results:
	Revenue	$	24,847		$	19,430		$	26,514		$	20,429		$	26,678		$	20,146		$	29,415		$	21,884
	Gross profit		17,657			14,086			18,781			15,123			18,892			14,685			20,420			15,669
	Loss from operations		(7,925	)		(1,800	)		(2,853	)		(1,639	)		(803	)		(2,614	)		(4,779	)		(4,838	)
	Net loss		(7,709	)		(1,943	)		(2,692	)		(1,791	)		(466	)		(2,748	)		(5,344	)		(4,980	)
	Net loss per share (basic and diluted)	$	(0.31	)	$	(0.10	)	$	(0.10	)	$	(0.09	)	$	(0.02	)	$	(0.13	)	$	(0.20	)	$	(0.24	)

Description_of_Business_and_Su3

Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Description Of Business And Significant Accounting Policies [Line Items]
Maturity period of short term investment	1 year
Shipping and handling revenue	$952	$786	$723
Payment terms for end-users	30 days
Payment terms for distributors	60 days
Foreign currency transaction (losses) gains	-161	-209	115
Grant income	731	0	409
(Income) expense related to remeasurement of fair value of fully vested stock options	-183	272	-179
Company's expense related to the medical device excise tax	592	417
Options, restricted stock and performance based shares excluded from calculation of net loss per share	3,772	2,721	3,676
Share-based compensation expense recognized	7,571	3,080	3,468
Non-Compete Agreement [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Amortization period	8 years
Fusion Technology [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Amortization period	10 years
Clamp and Probe Technology [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Amortization period	3 years
Estech Trade Name [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Amortization period	1 year
Subsidiaries [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Foreign currency transaction (losses) gains	($523)	$269	($83)
Computer and Other Office Equipment [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category	3 years
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_Su4

Description of Business and Summary of Significant Accounting Policies - Accumulated Other Comprehensive Income (Loss) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance				($37)
Beginning Balance				-37
Ending Balance	-348	-139	77	-37
Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	-6	1	2
Other comprehensive income (loss) before reclassifications	-48	-7	-1
Beginning Balance	-6	1	2
Other comprehensive income (loss) before reclassifications	-48	-7	-1
Ending Balance	-54	-6	1
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	-133	76	-39
Other comprehensive income (loss) before reclassifications	362	-478	198
Amounts reclassified from accumulated other comprehensive income (loss) to other income	-523	269	-83
Beginning Balance	-133	76	-39
Other comprehensive income (loss) before reclassifications	362	-478	198
Ending Balance	($294)	($133)	$76

Fair_Value_Financial_Assets_an

Fair Value - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Liabilities:
Acquisition-related contingent consideration	$8,032
Significant Other Unobservable Inputs (Level 3) [Member]
Liabilities:
Acquisition-related contingent consideration	0	8,032
Fair Value, Measurements, Recurring [Member]
Assets:
Total assets	63,851	23,528
Liabilities:
Derivative instruments	120	350
Acquisition-related contingent consideration		8,032
Total liabilities	120	8,382
Fair Value, Measurements, Recurring [Member] \| Money Market Funds [Member]
Assets:
Total assets	23,692	4,295
Fair Value, Measurements, Recurring [Member] \| Commercial Paper [Member]
Assets:
Total assets	1,800	2,598
Fair Value, Measurements, Recurring [Member] \| U.S. Government Agencies and Securities [Member]
Assets:
Total assets	3,022	4,145
Fair Value, Measurements, Recurring [Member] \| Corporate Bonds [Member]
Assets:
Total assets	35,337	12,490
Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Total assets	3,022	4,145
Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| U.S. Government Agencies and Securities [Member]
Assets:
Total assets	3,022	4,145
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets	60,829	19,383
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Money Market Funds [Member]
Assets:
Total assets	23,692	4,295
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Commercial Paper [Member]
Assets:
Total assets	1,800	2,598
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Corporate Bonds [Member]
Assets:
Total assets	35,337	12,490
Fair Value, Measurements, Recurring [Member] \| Significant Other Unobservable Inputs (Level 3) [Member]
Liabilities:
Derivative instruments	120	350
Acquisition-related contingent consideration		8,032
Total liabilities	$120	$8,382

Fair_Value_Additional_Informat

Fair Value - Additional Information (Detail) (USD $)	12 Months Ended
Fair Value - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Changes in levels of financial assets and liabilities	$0	$0
Acquisition-related contingent consideration	8,032,000
Significant Other Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquisition-related contingent consideration	0	8,032,000
Maximum [Member] \| Estech [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquisition-related contingent consideration	$26,000,000

Fair_Value_Assumptions_Used_fo

Fair Value - Assumptions Used for Estimating Fair Value of Level 3 Liabilities (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Risk-free interest rate	0.07%
Expected life of option (years)	8 months 12 days
Expected volatility of stock	39.91%	70.00%
Dividend yield	0.00%	0.00%
Minimum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Risk-free interest rate		0.11%
Expected life of option (years)		9 months
Maximum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Risk-free interest rate		1.32%
Expected life of option (years)		4 years 1 month 6 days

Fair_Value_Level_3_Fair_Value_

Fair Value - Level 3 Fair Value Measurements Using Significant Other Unobservable Inputs for Derivative Instruments (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Beginning Balance	$350	$78	$208
Total (gains) losses included in earnings	-183	272	-179
Exercises	-47		-50
Reclassification from equity to liability when fully vested			99
Ending Balance	$120	$350	$78

Fair_Value_Level_3_Fair_Value_1

Fair Value - Level 3 Fair Value Measurements Using Significant Other Unobservable Inputs for Acquisition Related Contingent Consideration (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument Fair Value Carrying Value [Abstract]
Beginning Balance	$8,032
Amounts acquired		8,032
Transfers in (out) of Level 3	0	0	0
Changes in fair value included in earnings	-8,032
Ending Balance		$8,032

Investments_Summary_of_Shortte

Investments - Summary of Short-term Investments (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investment [Line Items]
Short-term investments, Cost Basis	$40,213	$19,239
Short-term investments, Fair value	40,159	19,233
Short-term investment, Unrealized gains (losses)	-54	-6
Corporate Bonds [Member]
Investment [Line Items]
Short-term investments, Cost Basis	35,389	12,498
Short-term investments, Fair value	35,337	12,490
Short-term investment, Unrealized gains (losses)	-52	-8
U.S. Government Agencies and Securities [Member]
Investment [Line Items]
Short-term investments, Cost Basis	3,024	4,143
Short-term investments, Fair value	3,022	4,145
Short-term investment, Unrealized gains (losses)	-2	2
Commercial Paper [Member]
Investment [Line Items]
Short-term investments, Cost Basis	1,800	2,598
Short-term investments, Fair value	$1,800	$2,598

Investments_Additional_Informa

Investments - Additional Information (Detail)	12 Months Ended
Investments - Additional Information (Detail)	Dec. 31, 2014	Dec. 31, 2013
Minimum [Member]
Investment [Line Items]
Long term marketable debt securities maturity period	1 year
Maximum [Member]
Investment [Line Items]
Long term marketable debt securities maturity period	5 years	5 years

Business_Combination_Additiona

Business Combination - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Business Combination Transactions [Line Items]
Consideration related to earnout calculation	$26,000
Contingent consideration on acquisition	8,032
Contingent consideration on acquisition, change in value	-8,032
Business combination, receivable	1,275
Minimum [Member]
Business Combination Transactions [Line Items]
Milestone payment	3,000
Milestone achievement payment	9000.00%
Maximum [Member]
Business Combination Transactions [Line Items]
Milestone payment	13,000
Milestone achievement payment	12500.00%
Estech [Member]
Business Combination Transactions [Line Items]
Acquisition of shares and voting interest		100.00%
Consideration paid to former shareholders		34,000
Acquisition related costs		1,207
Acquisition related costs expensed		298
Estech [Member] \| Bank Fees and Expenses [Member]
Business Combination Transactions [Line Items]
Acquisition related costs		509
Estech [Member] \| Legal, Audit, Tax and Other Costs [Member]
Business Combination Transactions [Line Items]
Acquisition related costs		698
Estech [Member] \| Maximum [Member]
Business Combination Transactions [Line Items]
Contingent consideration on acquisition	26,000
Estech [Member] \| Common Stock [Member]
Business Combination Transactions [Line Items]
Consideration paid to former shareholders		39,720
Issuance of common stock		2,126,343
Common stock, par value		$15.99
Common stock, closing price		$18.68
Selling, General and Administrative Expenses [Member]
Business Combination Transactions [Line Items]
Contingent consideration on acquisition	$8,032

Business_Combination_Summary_o

Business Combination - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Combinations [Abstract]
Cash and cash equivalents		$3,708
Accounts receivable		2,378
Inventories		2,156
Other current assets		271
Property and equipment, net		1,026
Intangible assets, net		10,279
Other assets		51
Total identifiable assets		19,869
Accounts payable		1,761
Accrued liabilities		5,742
Total liabilities assumed		7,503
Net identifiable assets acquired		12,366
Goodwill	35,386	35,386	0
Total consideration		$47,752

Business_Combination_Valuation

Business Combination - Valuation of Intangible Assets Acquired and Related Amortization Periods (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets		$10,279
Estech [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets	10,279
Estech [Member] \| Fusion Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets	9,242
Intangible assets amortization period	10 years
Estech [Member] \| Clamp and Probe Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets	829
Intangible assets amortization period	3 years
Estech [Member] \| Estech Trade Name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets	$208
Intangible assets amortization period	1 year

Business_Combination_Pro_forma

Business Combination - Pro forma Acquisition Information (Detail) (Estech [Member], USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Estech [Member]
Business Acquisition Pro Forma Information [Line Items]
Revenue	$93,846	$81,954
Net loss	($21,161)	($19,031)
Basic and diluted net loss per share	($0.91)	($1.04)

Intangible_Assets_and_Goodwill2

Intangible Assets and Goodwill - Summary of Company's Intangible Assets with Definite Lives (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Cost	$10,379	$10,379
Accumulated Amortization	1,501	80
Non-Compete Agreement [Member]
Goodwill [Line Items]
Cost	100	100
Accumulated Amortization	93	80
Fusion Technology [Member]
Goodwill [Line Items]
Cost	9,242	9,242
Accumulated Amortization	924
Clamp and Probe Technology [Member]
Goodwill [Line Items]
Cost	829	829
Accumulated Amortization	276
Estech Trade Name [Member]
Goodwill [Line Items]
Cost	208	208
Accumulated Amortization	$208

Intangible_Assets_and_Goodwill3

Intangible Assets and Goodwill - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$1,421	$12	$13

Intangible_Assets_and_Goodwill4

Intangible Assets and Goodwill - Future Amortization Expense Related to Intangible Assets with Definite Lives (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Expected amortization expense in 2015	$1,208
Expected amortization expense in 2016	1,201
Expected amortization expense in 2017	924
Expected amortization expense in 2018	924
Expected amortization expense in 2019	924
Expected amortization expense in 2020 and thereafter	3,697
Total	$8,878

Intangible_Assets_and_Goodwill5

Intangible Assets and Goodwill - Summary of Company's Goodwill (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Intangible Liability Disclosure [Abstract]
Net carrying amount, Beginning Balance	$35,386	$0
Adjustments	0
Additions		35,386
Net carrying amount, Ending Balance	$35,386	$35,386

Inventories_Summary_of_Invento

Inventories - Summary of Inventories (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials	$4,429	$3,279
Work in process	1,397	1,472
Finished goods	8,431	5,463
Inventories	$14,257	$10,214

Property_and_Equipment_Summary

Property and Equipment - Summary of Property and Equipment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$19,239	$12,473
Less accumulated depreciation	-7,687	-6,830
Property and equipment, net	11,552	5,643
Generators and Other Capital Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8,578	6,896
Property and equipment, net	4,141	3,173
Machinery, Equipment and Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,604	3,021
Computer and Other Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,436	1,522
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	488	208
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	329	262
New Headquarters Building [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	162	153
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$4,642	$411

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Depreciation	$3,353	$2,008	$1,886
Net carrying amount	11,552	5,643
Generators and Other Capital Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation	2,172	1,251	1,081
Net carrying amount	4,141	3,173
Building [Member]
Property, Plant and Equipment [Line Items]
Cost on construction of headquarters building	$4,234

Accrued_Liabilities_Accrued_Li

Accrued Liabilities - Accrued Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Payables and Accruals [Abstract]
Accrued bonus	$4,915,000	$6,849,000
Accrued commissions	4,477,000	3,827,000
Accrued payroll and employee-related expenses	2,281,000	1,404,000
Accrued taxes and value-added taxes payable	1,272,000	907,000
Accrued royalties	442,000	307,000
Other accrued liabilities	399,000	1,062,000
Sales returns allowance	135,000	105,000
Accrued non-employee stock options	120,000	350,000
Accrued settlement reserve (current portion)	0	1,259,000
Total	$14,041,000	$16,070,000

Indebtedness_LongTerm_Debt_and

Indebtedness - Long-Term Debt and Capital Leases (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Credit facility		$6,333
Capital leases	114	117
Total debt and capital leases	114	6,450
Less: Current maturities	-3,981	-2,038
Total long-term debt and capital leases	$74	$4,412

Indebtedness_Additional_Inform

Indebtedness - Additional Information (Detail)	12 Months Ended			12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014
	USD ($)	EUR (€)	Silicon Valley Bank [Member]	Revolving Credit Facility [Member]
	Milestone		Maximum [Member]	USD ($)
			USD ($)
Credit Facilities [Line Items]
Credit facility	$15,000			$12,383
Revolving credit facility maturity date				30-Apr-16
Term loan arrangements	10,000
Amortization expenses	37
Cash and investments with SVB			20,000
Covenant milestones met	0
Increase to the applicable interest rate	3.00%
Borrowing availability under the revolving credit facility				15,000
Borrowings under the revolving credit facility				0
Letter of credit outstanding		75
Expiry of outstanding letter of credit	30-Jun-15
Capital lease expiration period	2018
Cost of assets under lease	162
Accumulated amortization on the capital leases	$59

Indebtedness_Future_Maturities

Indebtedness - Future Maturities on Debt, Including Capital Lease Obligations (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Debt and capital leases obligation maturities in 2015	$45
Debt and capital leases obligation maturities in 2016	44
Debt and capital leases obligation maturities in 2017	24
Debt and capital leases obligation maturities in 2018	10
Total debt and capital leases	123
Imputed interest	-9
Net capital lease obligations	$114	$117

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies [Line Items]
Operating leases expire at various terms	2021
Operating lease rent expense	$1,331,000	$870,000	$769,000
Letter of credit to be issued to landlord, amount	1,250,000
Royalty expense	1,322,000	962,000	603,000
Expense related to the departure of the Company's Chief Financial Officer and Chief Executive Officer			1,600,000
Settlement agreement payments (including interest)	4,350,000
Liability related settlement current	0	1,259,000
Chief Financial Officer [Member]
Commitments and Contingencies [Line Items]
Officer salary			250,000
Chief Executive Officer [Member]
Commitments and Contingencies [Line Items]
Officer salary			225,000
Minimum [Member]
Commitments and Contingencies [Line Items]
Royalty rates	0.75%
Royalty payments	50,000
Royalty agreement term	3 years
Maximum [Member]
Commitments and Contingencies [Line Items]
Royalty rates	5.00%
Royalty payments	2,000,000
Royalty agreement term	20 years
New Headquarters Building [Member]
Commitments and Contingencies [Line Items]
Annual lease payments	1,400,000
Mason Lease [Member]
Commitments and Contingencies [Line Items]
Lease term period	15 years
Number of renewal options	3
Lease renewal option period	5 years
Initial annual base rent	1,353,000
Lease rate increase, percentage	2.00%
Area of lease	92
Project cost included in the construction of building	3,941,000
Mason Lease [Member] \| Leasehold Improvements [Member]
Commitments and Contingencies [Line Items]
Leases payable, amount	$750,000

Commitments_and_Contingencies_2

Commitments and Contingencies - Future Minimum Lease Payments Under Non-cancelable Operating Leases (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
2015	$839
2016	240
2017	172
2018	174
2019	171
2020 and thereafter	140
Total	$1,736

Income_Taxes_Detail_of_Deferre

Income Taxes - Detail of Deferred Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets (liabilities):
Net operating loss carryforward	$49,921	$46,362
Research and development and AMT credit carryforwards, net	4,799	4,425
Equity compensation	4,497	2,477
Accruals and reserves	536	1,007
Inventories	669	290
Intangible assets	-149	-186
Property and equipment, net	-760	-173
Other, net	41	9
Subtotal	59,554	54,211
Less valuation allowance	-59,554	-54,211
Total	$0	$0

Income_Taxes_Companys_Provisio

Income Taxes - Company's Provision for Income Taxes (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Current income tax expense	$33	$18	$50
Deferred tax benefit	-5,306	-3,728	-2,336
Increase in valuation allowance	5,306	3,728	2,336
Total income tax expense	$33	$18	$50

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
Income Taxes - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Research and development credit carryforward	$4,799,000	$4,425,000
Pre-tax book loss for domestic operations	-11,085,000	-9,409,000	-5,909,000
Pre-tax book loss for international operations	-5,093,000	-2,035,000	-1,575,000
Unrecognized deferred tax assets	3,873,000
Unrecognized tax benefits	0	0	0
Unrecognized tax benefits, increase resulting from prior period tax positions	1,982,000	1,982,000
Unrecognized tax benefits, accrued interest and penalties	0
Federal [Member]
Income Tax Contingency [Line Items]
Operating loss carryforward	129,976,000
Operating loss Carryforward expiration date	Begin to expire in 2019
Research and development credit carryforward	4,697,000
Federal research and development credit credit carry forward expiry	2022
State [Member]
Income Tax Contingency [Line Items]
Operating loss carryforward	71,470,000
Foreign [Member]
Income Tax Contingency [Line Items]
Operating loss carryforward	$14,098,000
Operating loss Carryforward expiration date	Begin to expire in 2016
Minimum [Member] \| State [Member]
Income Tax Contingency [Line Items]
State Operating loss carryforward expiry date	5 years
Maximum [Member] \| State [Member]
Income Tax Contingency [Line Items]
State Operating loss carryforward expiry date	20 years

Income_Taxes_Difference_Betwee

Income Taxes - Difference Between Effective Income Tax Rates and Federal Statutory Rate (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Federal tax at statutory rate	34.00%	34.00%	34.00%
Federal R&D credit	2.32%	3.35%	0.08%
Valuation allowance	-32.80%	-29.63%	-31.98%
State income taxes	2.68%	0.04%	0.67%
Foreign NOL rate change	-4.29%	2.47%	1.40%
Foreign tax rate differential	-2.83%	-1.60%	-1.94%
Other	0.72%	-8.79%	-2.91%
Effective tax rate	-0.20%	-0.16%	-0.68%
Federal tax at statutory rate	($5,501)	($3,891)	($2,483)
Federal R&D credit	-374	-383	-6
Valuation allowance	5,306	3,391	2,336
State income taxes	-433	-5	-49
Foreign NOL rate change	694	-283	-102
Foreign tax rate differential	458	183	142
Other	-117	1,006	212
Total income tax expense	$33	$18	$50

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of Change in Federal and State Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Balance at the beginning of the year	$1,982
Increases (decreases) for prior year tax positions	1,982	1,982
Increases (decreases) for current year tax positions	0	0	0
Increases (decreases) related to settlements	0	0	0
Decreases related to statute lapse	0	0	0
Balance at the end of the year	$1,982	$1,982

Concentrations_Additional_Info

Concentrations - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Customer	Dec. 31, 2013	Dec. 31, 2012
Concentration Risk [Line Items]
Percentage representation of significant customer	13.60%	20.40%	19.60%
Number of customers	10
Cash and cash equivalents balance in excess of FDIC limits	$28,457
Customer Concentration Risk [Member] \| Net Revenue [Member]
Concentration Risk [Line Items]
Percentage representation of significant customer	10.00%
Customer Concentration Risk [Member] \| Accounts Receivable [Member]
Concentration Risk [Line Items]
Percentage representation of significant customer	8.70%	11.50%
Number of customers	1	1

Employee_Benefit_Plans_Additio

Employee Benefit Plans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Employee contribution percent	50.00%	50.00%	25.00%
Maximum percentage of employee contribution to the plan	6.00%	6.00%	6.00%
Company's matching contribution	$807,000	$606,000	$234,000
Discretionary contributions made	0	0	0
Total contributions to retirement plan	$176,000	$176,000	$114,000

Equity_Compensation_Plans_2001

Equity Compensation Plans - 2001 Plan, 2005 Plan and 2014 Plan - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended			1 Months Ended
Share data in Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised			$2,311,000	$951,000	$1,338,000
Tax benefit recognized			0	0	0
Proceeds from stock option exercises			1,916,000	1,718,000	659,000
Share-based compensation expense recognized			7,571,000	3,080,000	3,468,000
Unrecognized compensation costs related to non-vested share-based compensation arrangements with performance shares			15,913,000
Recognized expense related to performance options			7,571,000	3,080,000	3,468,000
Incremental compensation expenses	522,000	396,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period of recognizing cost			8 months 1 day
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period of recognizing cost			3 years 18 days
2001 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiry of options from the date of grant			10 years
2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiry of options from the date of grant			10 years
Restricted stock awards granted annual vest rate			25.00%
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiry of options from the date of grant			10 years
Restricted stock awards granted annual vest rate			25.00%
Common stock reserved for issuance			8,949
Common stock authorized for issuance			1,300
Shares available for future grants under plans			2,233
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options compensation costs			8,775,000
Weighted average period of recognizing cost			2 years 6 months
Employee Stock Option [Member] \| 2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable period beginning			3 years
Options granted exercisable cumulative			25.00%
Employee Stock Option [Member] \| 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable period beginning			3 years
Options granted exercisable cumulative			25.00%
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of restricted stock vested			1,434,000	1,442,000	1,292,000
Unrecognized compensation costs related to non-vested performance options			7,138,000
Weighted average period of recognizing cost			2 years 8 months 12 days
Performance options awarded to President and CEO			391	55
Restricted Stock [Member] \| 2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted from the 2005 Plan generally vest			4 years
Restricted Stock [Member] \| 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted from the 2005 Plan generally vest			4 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiry of options from the date of grant			10 years
Total fair value of performance shares vested			0	0	99,000
Unrecognized compensation costs related to non-vested performance options			859,000
Performance options awarded to President and CEO						225
Number of shares options vest in			25
Period of considering closing price of common stock			30 days
Recognized expense related to performance options			1,767,000	272,000	36,000
Performance Shares [Member] \| Tranche 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$10
Performance Shares [Member] \| Tranche 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$12.50
Performance Shares [Member] \| Tranche 3 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$15
Performance Shares [Member] \| Tranche 4 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$17.50
Performance Shares [Member] \| Tranche 5 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$20
Performance Shares [Member] \| Tranche 6 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$25
Performance Shares [Member] \| Tranche 7 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$30
Performance Shares [Member] \| Tranche 8 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$35
Performance Shares [Member] \| Tranche 9 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price by which volume adjusted weighted average closing price exceeds under vesting condition			$40
Time Based Stock Options and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized			$5,383,000	$2,489,000	$3,211,000

Equity_Compensation_Plans_Acti

Equity Compensation Plans - Activity Under Stock Based Compensation Plans (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of Shares Outstanding, Stock Options	2,423	3,172
Granted, Number of Shares Outstanding, Stock Options	603	451
Cancelled or forfeited, Number of Shares Outstanding, Stock Options	-49	-912
Exercised, Number of Shares Outstanding, Stock Options	-215	-288
Ending balance, Number of Shares Outstanding, Stock Options	2,762	2,423
Vested and expected to vest, Number of Shares Outstanding, Stock Options	2,660	2,302
Exercisable, Ending balance, Number of Shares Outstanding, Stock Options	1,516	1,363
Beginning balance, Weighted Average Exercise Price, Stock Options	$8.61	$8.81
Granted, Weighted Average Exercise Price, Stock Options	$19.54	$9.01
Cancelled or forfeited, Weighted Average Exercise Price, Stock Options	$10.65	$10.34
Exercised, Weighted Average Exercise Price, Stock Options	$8.94	$5.98
Ending balance, Weighted Average Exercise Price, Stock Options	$10.93	$8.61
Vested And expected to vest, Weighted Average Exercise Price, Stock Options	$10.81	$8.66
Exercisable, Ending balance, Weighted Average Exercise Price, Stock Options	$8.85	$9.07
Outstanding, Ending balance, Weighted Average Remaining Contractual Term, Stock Options	6 years 6 months 15 days	6 years 5 months 19 days
Vested and expected to vest, Weighted Average Remaining Contractual Term, Stock Options	6 years 5 months 16 days	6 years 4 months 2 days
Exercisable, Ending balance, Weighted Average Remaining Contractual Term, Stock Options	4 years 10 months 10 days	4 years 7 months 2 days
Outstanding, Ending balance, Aggregate Intrinsic Value, Stock Options	$25,335	$24,403
Vested and expected to vest, Aggregate Intrinsic Value, Stock Options	24,697	23,082
Exercisable, Ending balance, Aggregate Intrinsic Value, Stock Options	16,836	13,102
Performance Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of Shares Outstanding, Stock Options	225	225
Granted, Number of Shares Outstanding, Stock Options	225
Ending balance, Number of Shares Outstanding, Stock Options	450	225
Exercisable, Ending balance, Number of Shares Outstanding, Stock Options	250	50
Beginning balance, Weighted Average Exercise Price, Stock Options	$5.91	$5.91
Granted, Weighted Average Exercise Price, Stock Options	$21.04
Ending balance, Weighted Average Exercise Price, Stock Options	$13.48	$5.91
Exercisable, Ending balance, Weighted Average Exercise Price, Stock Options	$13.48	$5.91
Outstanding, Ending balance, Weighted Average Remaining Contractual Term, Stock Options	8 years 6 months	8 years 9 months 18 days
Exercisable, Ending balance, Weighted Average Remaining Contractual Term, Stock Options	8 years 6 months	8 years 9 months 18 days
Outstanding, Ending balance, Aggregate Intrinsic Value, Stock Options	3,161	2,873
Exercisable, Ending balance, Aggregate Intrinsic Value, Stock Options	$1,756	$639
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of Shares Outstanding	248
Awarded, Number of Shares Outstanding	391	55
Forfeited, Number of Shares Outstanding	-1	-184
Released, Number of Shares Outstanding	-78	-127
Ending balance, Number of Shares Outstanding	560	248
Beginning balance, Weighted Average Grant Date Fair Value	$7.75	$7.93
Awarded, Weighted Average Grant Date Fair Value	$20.25	$9.35	$7.69
Forfeited, Weighted Average Grant Date Fair Value	$9.15	$8.20
Released, Weighted Average Grant Date Fair Value	$8.79	$8.49
Ending balance, Weighted Average Grant Date Fair Value	$16.33	$7.75	$7.93

Equity_Compensation_Plans_Empl

Equity Compensation Plans - Employee Stock Purchase Plan - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
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 more than 3 shares during an offering period.
Participants purchase limit shares	3,000
Offering period	6 months
Share-based compensation expense recognized	$7,571	$3,080	$3,468
ESPP [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	578,000
Share-based compensation expense recognized	$421	$319	$257

Equity_Compensation_Plans_Summ

Equity Compensation Plans - Summary of Share-Based Compensation Expense Related to Employee Share-Based Compensation (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	$7,571	$3,080	$3,468
Cost of Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	335	246	272
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	937	230	267
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	$6,299	$2,604	$2,929

Equity_Compensation_Plans_Assu

Equity Compensation Plans - Assumptions Used for Determining Fair Value of Options (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility of stock		69.00%
Weighted-average volatility	69.19%	69.00%	69.50%
Dividend yield	0.00%	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.56%	0.75%	0.65%
Expected life of option (years)	5 years 3 months 22 days	5 years 3 months 22 days	5 years 3 months 22 days
Expected volatility of stock	47.00%	69.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.12%	2.29%	1.37%
Expected life of option (years)	6 years 8 months 19 days	7 years 4 months 17 days	7 years 1 month 21 days
Expected volatility of stock	70.00%	71.00%

Equity_Compensation_Plans_Weig

Equity Compensation Plans - Weighted Average Estimated Grant Date Fair Value Per Share of Stock Options and Restricted Stock Granted (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average estimated grant date fair value per share of the stock options granted	$12.33	$5.70	$4.65
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average estimated grant date fair value per share of the restricted stock granted	$20.25	$9.35	$7.69

Equity_Compensation_Plans_Assu1

Equity Compensation Plans - Assumptions Used for Determining Fair Value of Option (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility of stock		69.00%
Dividend yield	0.00%	0.00%	0.00%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Strike price		5.91
Contractual term (years)	10 years	10 years
Expected volatility of stock		69.60%
Interest rate		1.75%
Dividend yield	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term (years)	5 years 3 months 22 days	5 years 3 months 22 days	5 years 3 months 22 days
Expected volatility of stock	47.00%	69.00%
Interest rate	1.56%	0.75%	0.65%
Minimum [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Strike price	5.91
Expected volatility of stock	60.50%
Interest rate	1.75%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term (years)	6 years 8 months 19 days	7 years 4 months 17 days	7 years 1 month 21 days
Expected volatility of stock	70.00%	71.00%
Interest rate	2.12%	2.29%	1.37%
Maximum [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Strike price	21.04
Expected volatility of stock	69.60%
Interest rate	2.73%

Equity_Compensation_Plans_Esti

Equity Compensation Plans - Estimated Grant Date Fair Value Per Share of Performance Options Granted (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$12.33	$5.70	$4.65
Performance Shares [Member] \| Tranche 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$10
Performance Shares [Member] \| Tranche 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$12.50
Performance Shares [Member] \| Tranche 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$15
Performance Shares [Member] \| Tranche 4 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$17.50
Performance Shares [Member] \| Tranche 5 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$20
Performance Shares [Member] \| Tranche 6 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$25
Performance Shares [Member] \| Tranche 7 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$30
Performance Shares [Member] \| Tranche 8 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$35
Performance Shares [Member] \| Tranche 9 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target	$40
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$4.32
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$4.30
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$4.27
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 4 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$4.23
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 5 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$4.19
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 6 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$4.10
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 7 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$4.01
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 8 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$3.92
Fair Value Of 2012 Grant [Member] \| Performance Shares [Member] \| Tranche 9 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$3.83
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.74
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.74
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.74
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 4 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.74
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 5 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.73
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 6 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.73
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 7 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.71
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 8 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.67
Fair Value Of 2014 Grant [Member] \| Performance Shares [Member] \| Tranche 9 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair Value	$14.61

Equity_Compensation_Plans_NonE

Equity Compensation Plans - Non-Employee Stock Compensation - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Nonstatutory common stock options vest period maximum	4 years
Stock options granted to non-employee consultants vesting period	4 years
Non-employee vesting stock rate	25.00%
(Income) expense related to remeasurement of fair value of fully vested stock options	($183)	$272	($179)
Unexercised shares of common stock held by non-employee consultants	20	38
Accrued non employee stock options	$120	$350

Segment_and_Geographic_Informa2

Segment and Geographic Information - Revenue by Product (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Product Type Reporting Information [Line Items]
Revenue	$29,415	$26,678	$26,514	$24,847	$21,884	$20,146	$20,429	$19,430	$107,454	$81,889	$70,247
United States [Member]
Product Type Reporting Information [Line Items]
Revenue									80,203	62,311	52,616
United States [Member] \| Open-heart [Member]
Product Type Reporting Information [Line Items]
Revenue									44,662	37,843	32,880
United States [Member] \| Minimally Invasive [Member]
Product Type Reporting Information [Line Items]
Revenue									16,050	13,648	12,733
United States [Member] \| AtriClip [Member]
Product Type Reporting Information [Line Items]
Revenue									16,675	10,820	7,003
United States [Member] \| Valve Tools [Member]
Product Type Reporting Information [Line Items]
Revenue									2,816
International [Member]
Product Type Reporting Information [Line Items]
Revenue									27,251	19,578	17,631
International [Member] \| Open-heart [Member]
Product Type Reporting Information [Line Items]
Revenue									16,445	13,064	11,972
International [Member] \| Minimally Invasive [Member]
Product Type Reporting Information [Line Items]
Revenue									7,881	5,354	4,813
International [Member] \| AtriClip [Member]
Product Type Reporting Information [Line Items]
Revenue									2,158	1,160	846
International [Member] \| Valve Tools [Member]
Product Type Reporting Information [Line Items]
Revenue									$767

Segment_and_Geographic_Informa3

Segment and Geographic Information - Summary of Revenue by Geographic Area Classified Based on Country Location of Customer (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Information About Revenue And Geographic Areas [Line Items]
Revenue	$29,415	$26,678	$26,514	$24,847	$21,884	$20,146	$20,429	$19,430	$107,454	$81,889	$70,247
United States [Member]
Information About Revenue And Geographic Areas [Line Items]
Revenue									80,203	62,311	52,616
Europe [Member]
Information About Revenue And Geographic Areas [Line Items]
Revenue									18,163	11,384	10,344
Asia [Member]
Information About Revenue And Geographic Areas [Line Items]
Revenue									8,552	7,665	6,730
Other International [Member]
Information About Revenue And Geographic Areas [Line Items]
Revenue									$536	$529	$557

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Unaudited) - Schedule of Quarterly Financial Information (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Results:
Revenue	$29,415	$26,678	$26,514	$24,847	$21,884	$20,146	$20,429	$19,430	$107,454	$81,889	$70,247
Gross profit	20,420	18,892	18,781	17,657	15,669	14,685	15,123	14,086	75,750	59,563	50,014
Loss from operations	-4,779	-803	-2,853	-7,925	-4,838	-2,614	-1,639	-1,800	-16,360	-10,891	-7,198
Net loss	($5,344)	($466)	($2,692)	($7,709)	($4,980)	($2,748)	($1,791)	($1,943)	($16,211)	($11,462)	($7,534)
Net loss per share (basic and diluted)	($0.20)	($0.02)	($0.10)	($0.31)	($0.24)	($0.13)	($0.09)	($0.10)

Valuation_and_Qualifying_Accou1

Valuation and Qualifying Accounts (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for doubtful accounts receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$94	$49	$37
Valuation and Qualifying Accounts, Additions	84	100	75
Valuation and Qualifying Accounts, Deductions	110	55	63
Ending Balance	68	94	49
Reserve for sales returns and allowances [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	105	105	40
Valuation and Qualifying Accounts, Additions	34		262
Valuation and Qualifying Accounts, Deductions	4		197
Ending Balance	135	105	105
Allowance for inventory valuation [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	782	267	206
Valuation and Qualifying Accounts, Additions	441	921	381
Valuation and Qualifying Accounts, Deductions	701	406	320
Ending Balance	522	782	267
Valuation allowance for deferred tax assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	54,211	31,685	29,316
Valuation and Qualifying Accounts, Additions	5,343	22,526	2,369
Ending Balance	$59,544	$54,211	$31,685