Axon Enterprise (AXON) 10-K 27 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 18, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	AXON ENTERPRISE, INC.
Entity Central Index Key	1,069,183
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		58,829,384
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 3,613

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 349,462	$ 75,105
Short-term investments	0	6,862
Accounts and notes receivable, net of allowance of $1,882 and $754 as of December 31, 2018 and 2017, respectively	130,579	56,064
Contract assets, net	13,960	0
Inventory	33,763	45,465
Prepaid expenses and other current assets	30,391	21,696
Total current assets	558,155	205,192
Property and equipment, net	37,893	31,172
Deferred income tax assets, net	19,347	15,755
Intangible assets, net	15,935	18,823
Goodwill	24,981	14,927
Long-term notes receivable, net of current portion	40,230	36,877
Other assets	22,999	15,366
Total assets	719,540	338,112
Current liabilities:
Accounts payable	15,164	8,592
Accrued liabilities	41,092	23,502
Contract with customer, liability, current	107,016	70,401
Current portion of business acquisition contingent consideration	0	1,693
Other current liabilities	37	89
Total current liabilities	166,011	107,950
Deferred revenue, net of current portion	74,417	54,881
Liability for unrecognized tax benefits	2,849	1,706
Long-term deferred compensation	3,235	3,859
Business acquisition contingent consideration, net of current portion	0	1,048
Other long-term liabilities	5,704	1,224
Total liabilities	252,216	170,668
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.00001 par value; 25,000,000 shares authorized; no shares issued and outstanding as of December 31, 2018 and 2017	0	0
Common stock, $0.00001 par value; 200,000,000 shares authorized; 58,810,637 and 52,969,869 shares issued and outstanding as of December 31, 2018 and 2017, respectively	1	1
Additional paid-in capital	453,400	201,672
Treasury stock at cost, 20,220,227 shares as of December 31, 2018 and 2017	(155,947)	(155,947)
Retained earnings	171,383	123,185
Accumulated other comprehensive loss	(1,513)	(1,467)
Total stockholders’ equity	467,324	167,444
Total liabilities and stockholders’ equity	719,540	338,112
Current portion of deferred revenue
Current liabilities:
Contract with customer, liability, current	107,016	70,401
Customer deposits
Current liabilities:
Contract with customer, liability, current	$ 2,702	$ 3,673

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance on accounts receivable	$ 1,882	$ 754
Preferred stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	58,810,637	52,969,869
Common stock, shares outstanding (in shares)	58,810,637	52,969,869
Treasury stock, shares (in shares)	20,220,227	20,220,227

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net sales	$ 420,068	$ 343,798	$ 268,245
Cost of sales	161,485	136,710	97,709
Gross margin	258,583	207,088	170,536
Sales, general and administrative	156,886	138,692	108,076
Research and development	76,856	55,373	30,609
Total operating expenses	233,742	194,065	138,685
Income from operations	24,841	13,023	31,851
Interest and other income (expense), net	3,263	2,738	(354)
Income before provision for income taxes	28,104	15,761	31,497
Provision (benefit) for income taxes	(1,101)	10,554	14,200
Net income	$ 29,205	$ 5,207	$ 17,297
Net income per share:
Basic (in dollars per share)	$ 0.52	$ 0.10	$ 0.33
Diluted (in dollars per share)	$ 0.50	$ 0.10	$ 0.32
Weighted average shares outstanding:
Basic (in shares)	56,392	52,726	52,667
Diluted (in shares)	57,922	53,898	53,536
Net income	$ 29,205	$ 5,207	$ 17,297
Foreign currency translation adjustments	(46)	(2,370)	820
Comprehensive income	29,159	2,837	18,117
Product
Net sales	327,635	285,859	238,573
Cost of sales	139,337	117,997	91,536
Service
Net sales	92,433	57,939	29,672
Cost of sales	$ 22,148	$ 18,713	$ 6,173

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2015		53,692,192		18,432,158
Beginning balance at Dec. 31, 2015	$ 157,004	$ 1	$ 178,143	$ (122,201)	$ 83	$ 100,978
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee plans (in shares)		421,128
Issuance of common stock under employee plans	(1,294)		(1,294)
Stock-based compensation	9,369		9,369
Excess tax benefit from stock-based compensation	1,438		1,438
Purchase of treasury stock (in shares)		(1,788,069)		(1,788,069)
Purchase of treasury stock	(33,746)			$ (33,746)
Net income	17,297					17,297
Foreign currency translation adjustments	820				820
Ending balance (in shares) at Dec. 31, 2016		52,325,251		20,220,227
Ending balance at Dec. 31, 2016	150,888	$ 1	187,656	$ (155,947)	903	118,275
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee plans (in shares)		644,618
Issuance of common stock under employee plans	(2,069)		(2,069)
Stock-based compensation	15,610		15,610
Net income	5,207					5,207
Foreign currency translation adjustments	(2,370)				(2,370)
Ending balance (in shares) at Dec. 31, 2017		52,969,869		20,220,227
Ending balance at Dec. 31, 2017	167,444	$ 1	201,672	$ (155,947)	(1,467)	123,185
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of applying a change in accounting principle	178		475			(297)
Issuance of common stock (in shares)		4,645,000
Issuance of common stock	233,993		233,993
Issuance of common stock for business combination (in shares)		58,843
Issuance of common stock for business combination	8,226		8,226
Issuance of common stock under employee plans (in shares)		1,136,925
Issuance of common stock under employee plans	(12,370)		(12,370)
Stock-based compensation	21,879		21,879
Net income	29,205					29,205
Foreign currency translation adjustments	(46)				(46)
Ending balance (in shares) at Dec. 31, 2018		58,810,637		20,220,227
Ending balance at Dec. 31, 2018	467,324	$ 1	$ 453,400	$ (155,947)	$ (1,513)	171,383
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of applying a change in accounting principle	$ 18,993					$ 18,993

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 29,205	$ 5,207	$ 17,297
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	10,615	8,041	3,658
Loss on disposal and abandonment of intangible assets	2,117	1,146	21
Purchase accounting adjustments to goodwill	0	(23)	520
Loss (gain) on disposal and impairment of property and equipment, net	303	(28)	42
Bond premium amortization	34	657	1,265
Stock-based compensation	21,879	15,610	9,369
Deferred income taxes	(3,592)	2,830	(5,167)
Unrecognized tax benefits	1,144	(191)	582
Tax benefit from stock-based compensation	0	0	(1,438)
Change in assets and liabilities:
Accounts and notes receivable	(67,643)	(35,305)	(28,438)
Inventory	14,804	(11,746)	(18,668)
Prepaid expenses and other assets	(12,739)	(8,992)	(10,611)
Accounts payable, accrued and other liabilities	13,506	1,530	18,399
Deferred revenue	54,242	39,735	34,304
Net cash provided by operating activities	63,875	18,471	21,135
Cash flows from investing activities:
Purchases of investments	(4,331)	(19,950)	(56,086)
Proceeds from call / maturity of investments	11,158	61,080	64,951
Purchases of property and equipment	(11,139)	(10,419)	(4,957)
Proceeds from disposal of property and equipment	0	24	42
Purchases of intangible assets	(558)	(1,024)	(3,495)
Business acquisitions, net of cash acquired	(4,990)	(10,629)	(3,500)
Net cash provided by (used in) investing activities	(9,860)	19,082	(3,045)
Cash flows from financing activities:
Net proceeds from equity offering	233,993	0	0
Repurchase of common stock	0	0	(33,746)
Proceeds from options exercised	1,757	1,383	478
Income and payroll tax payments for net-settled stock awards	(14,127)	(3,453)	(1,772)
Payment of contingent consideration for business acquisitions	(2,275)	(1,750)	(952)
Excess tax benefit from stock-based compensation	0	0	1,438
Net cash provided by (used in) financing activities	219,348	(3,820)	(34,554)
Effect of exchange rate changes on cash and cash equivalents	(774)	737	906
Net increase (decrease) in cash and cash equivalents	272,589	34,470	(15,558)
Cash and cash equivalents and restricted cash, beginning of year	78,438	43,968	59,526
Cash and cash equivalents and restricted cash, end of year	$ 349,462	$ 75,105	$ 40,651

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Summary of Significant Accounting Policies	Organization and Summary of Significant Accounting Policies Axon Enterprise, Inc. (“Axon”, the “Company”, "we", or "us") is a market-leading provider of law enforcement technology solutions. Our core mission is to protect life. We fulfill that mission through developing hardware and software products that advance the long term objectives of a) obsoleting the bullet, b) reducing social conflict, and c) enabling a fair and effective justice system. The accompanying consolidated financial statements include the accounts of Axon Enterprise, Inc. and our wholly owned subsidiaries. All material intercompany accounts, transactions, and profits have been eliminated. Basis of Presentation and Use of Estimates The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The preparation of these consolidated financial statements 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 consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions in these consolidated financial statements include: • product warranty reserves, • inventory valuation, • revenue recognition, • valuation of goodwill, intangible and long-lived assets, • recognition, measurement and valuation of current and deferred income taxes, • stock-based compensation, • recognition and measurement of contingencies and accrued litigation expense, and • fair values of identified tangible and intangible assets acquired and liabilities assumed in business combinations. Actual results could differ materially from those estimates. Cash, Cash Equivalents and Investments Cash, cash equivalents and investments include cash, money market funds, certificates of deposit, state and municipal obligations and corporate bonds. We place our cash and cash equivalents with high quality financial institutions. Although we deposit our cash with multiple financial institutions, our deposits regularly exceed federally insured limits. Cash and cash equivalents include funds on hand and highly liquid investments purchased with initial maturity of three months or less. Short-term investments include securities with an expected maturity date within one year of the balance sheet date that do not meet the definition of a cash equivalent, and long-term investments are securities with an expected maturity date greater than one year. Based on management’s intent and ability, our investments are classified as held to maturity investments and are recorded at amortized cost. Held-to-maturity investments are reviewed quarterly for impairment to determine if other-than-temporary declines in the fair value have occurred for any individual investment that may affect our intent and ability to hold the investment until recovery. Other-than-temporary declines in the value of held-to-maturity investments are recorded as expense in the period the determination is made. Inventory Inventories are stated at the lower of cost and net realizable value. Cost is determined using the weighted average cost of raw materials, which approximates the first-in, first-out (“FIFO”) method and includes allocations of manufacturing labor and overhead. Provisions are made to reduce potentially excess, obsolete or slow-moving inventories, as well as trial and evaluation inventories to their net realizable value. These provisions are based on management’s best estimate after considering historical demand, projected future demand, inventory purchase commitments, industry and market trends and conditions among other factors. We evaluate inventory costs for abnormal costs due to excess production capacity and treat such costs as period costs. Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation and amortization. Additions and improvements are capitalized, while ordinary maintenance and repair expenditures are charged to expense as incurred. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. Software Development Costs We expense software development costs, including costs to develop software products or the software component of products and services to be marketed to external users, before technological feasibility of such products is reached. We have determined that technological feasibility is reached shortly before the release of those products and as a result, the development costs incurred after the establishment of technological feasibility and before the release of those products are not material. Software development costs also include costs to develop software programs to be used solely to meet our internal needs and applications. We capitalize development costs related to these software applications once the preliminary project stage is complete and it is probable that the project will be completed and the software will be used to perform the intended function. Additionally, we capitalize qualifying costs incurred for upgrades and enhancements to existing software that result in additional functionality. Costs related to preliminary project planning activities, post-implementation activities, maintenance and minor modifications are expensed as incurred. Internal-use software is amortized on a straight line basis over its estimated useful life. We evaluate the useful lives of these assets on an annual basis and test for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets. Valuation of Goodwill, Intangible and Long-lived Assets We do not amortize goodwill and intangible assets with indefinite useful lives; rather, such assets are required to be tested for impairment at least annually, or sooner whenever events or changes in circumstances indicate that the assets may be impaired. We perform our annual impairment assessment in the fourth quarter of each year. Finite-lived intangible assets and other long-lived assets are amortized over their estimated useful lives. Management evaluates whether events and circumstances have occurred that indicate the remaining estimated useful life of long-lived assets and intangible assets may warrant revision or that the remaining balance of these assets, including intangible assets with indefinite lives, may not be recoverable. Circumstances that might indicate long-lived assets might not be recoverable could include, but are not limited to, a change in the product mix, a change in the way products and services are created, produced or delivered, or a significant change in the way our products are branded and marketed. When performing a review for recoverability, management estimates the future undiscounted cash flows expected to result from the use of the assets and their eventual disposition. The amount of the impairment loss, if impairment exists, is calculated based on the excess of the carrying amounts of the assets over their estimated fair value computed using discounted cash flows. During the year ended December 31, 2018 , we abandoned certain developed technology acquired in a business combination resulting in an impairment charge of $2.0 million which was included in sales, general and administrative expense in the accompanying statement of operations. During the year ended December 31, 2017, we abandoned certain developed technology acquired in a business combination resulting in an impairment charge of $1.0 million which was included in research and development expense in the accompanying statement of operations. The impairment charges were recorded within the Software and Sensors Segment. No impairment losses were recorded during the year ended December 31, 2016 . Customer Deposits We require deposits in advance of shipment for certain customer sales orders. Additionally, customers may elect to make deposits with us related to contracts for our products and services that were not executed as of the end of a reporting period. Customer deposits are recorded as a current liability in the accompanying consolidated balance sheets. Revenue Recognition, Deferred Revenue and Accounts and Notes Receivable We derive revenue from two primary sources: (1) the sale of physical products, including CEWs, Axon cameras, Axon Signal enabled devices, corresponding hardware extended warranties, and related accessories such as Axon docks, cartridges and batteries, among others, and (2) subscriptions to our Axon Evidence digital evidence management software as a service ("SaaS") (including data storage fees and other ancillary services), which includes varying levels of support. To a lesser extent, we also recognize training, professional services and revenue related to other software and SaaS services. We apply the five-step model outlined in Accounting Standards Codification Topic 606, Revenue from Contracts from Customers ("Topic 606"). For additional discussion of the adoption of Topic 606, see Note 2. Many of our products and services are sold on a standalone basis. We also bundle our hardware products and services together and sell them to our customers in single transactions, where the customer can make payments over a multi-year period. These sales may include payments for upfront hardware and services, as well as payments for hardware and services to be provided by us at a future date. Additionally, we offer customers the ability to purchase CEW cartridges and certain services on an unlimited basis over the contractual term. Due to the unlimited nature of these arrangements whereby we are obligated to deliver unlimited products at the customer’s request, we account for these arrangements as stand-ready obligations, and recognize revenue ratably over the contract period. Cost of product sales is recognized as the products are shipped to the customer. Revenues are recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration we expect to receive in exchange for those products or services. We enter into contracts that can include various combinations of products and services, each of which is generally distinct and accounted for as a separate performance obligation. Revenue is recognized net of allowances for returns and any taxes collected from customers, which are subsequently remitted to governmental taxing authorities. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer, and is the unit of account in Topic 606. For contracts with multiple performance obligations, we allocate the contract transaction price to each performance obligation using our estimate of the standalone selling price ("SSP") of each distinct good or service in the contract. Performance obligations to deliver products, including CEWs, cameras and related accessories such as cartridges, batteries and docks, are generally satisfied at the point in time we ship the product, as this is when the customer obtains control of the asset under our standard terms and conditions. In certain contracts with non-standard terms and conditions, these performance obligations may not be satisfied until formal customer acceptance occurs. Performance obligations to fulfill service-type extended warranties and provide our SaaS offerings, including Axon Evidence and other cloud services, are generally satisfied over time as the customer receives and consumes the benefits of these services over the stated service period. We have elected to recognize shipping costs as an expense in cost of product sales when the control of hardware products or accessories have transferred to the customer. Sales tax collected on sales is netted against government remittances and thus, recorded on a net basis. Deferred revenue consists of payments received and amounts invoiced in advance related to products and services for which the criteria for revenue recognition have not yet been met. Deferred revenue that will be recognized during the subsequent twelve month period from the balance sheet date is recorded as current deferred revenue and the remaining portion is recorded as long-term. Generally, customers are billed in annual installments. See Note 2 for further disclosures about our deferred revenue. Sales are typically made on credit, and we generally do not require collateral. Management performs ongoing credit evaluations of its customers’ financial condition, and maintains an allowance for doubtful accounts. Uncollectible accounts are charged to expense when deemed uncollectible, and accounts and notes receivable are presented net of an allowance for doubtful accounts. This allowance represents management’s best estimate and application of judgment considering a number of factors, including third-party credit reports, actual payment history, cash discounts, customer-specific financial information and broader market and economic trends and conditions. In the event that actual uncollectible amounts differ from our estimates, additional expense could be necessary. Cost of Product and Service Sales Cost of product sales represents manufacturing costs, consisting of materials, labor and overhead related to finished goods and components. Shipping costs incurred related to product delivery are also included in cost of products sold. Cost of service sales includes third-party cloud services, and software maintenance and support costs, including personnel costs, associated with supporting Evidence.com and other software related services. Advertising Costs We expense advertising costs in the period in which they are incurred. We incurred advertising costs of $1.1 million , $0.5 million and $0.4 million in the years ended December 31, 2018 , 2017 and 2016 , respectively. Advertising costs are included in sales, general and administrative expenses in the accompanying statements of operations. Standard Warranties We warranty our CEWs, Axon cameras and certain related accessories from manufacturing defects on a limited basis for a period of one year after purchase and, thereafter, will replace any defective unit for a fee. Estimated costs for the standard warranty are charged to cost of products sold when revenue is recorded for the related product. Future warranty costs are estimated based on historical data related to warranty claims on a quarterly basis and this rate is applied to current product sales. Historically, reserve amounts have been increased if management becomes aware of a component failure or other issue that could result in larger than anticipated warranty claims from customers. The warranty reserve is reviewed quarterly to verify that it sufficiently reflects the remaining warranty obligations based on the anticipated expenditures over the balance of the warranty obligation period, and adjustments are made when actual warranty claim experience differs from estimates. The warranty reserve is included in accrued liabilities on the accompanying consolidated balance sheets. Changes in our estimated warranty reserve were as follows (in thousands): 2018 2017 2016 Balance, January 1 $ 644 $ 780 $ 314 Utilization of reserve (458 ) (245 ) (155 ) Warranty expense 712 109 621 Balance, December 31 $ 898 $ 644 $ 780 Research and Development Expenses We expense as incurred research and development costs that do not meet the qualifications to be capitalized. We incurred research and development expense of $76.9 million , $55.4 million and $30.6 million in 2018 , 2017 and 2016 , respectively. Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement amounts of assets and liabilities and their respective tax bases and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in future years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rate is recognized in income in the period that includes the enactment date. Deferred tax assets are reduced through the establishment of a valuation allowance if, based upon available evidence, it is determined that it is more likely than not that the deferred tax assets will not be realized. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate resolution. Management also assesses whether uncertain tax positions, as filed, could result in the recognition of a liability for possible interest and penalties. Our policy is to include interest and penalties related to unrecognized tax benefits as a component of income tax expense. Refer to Note 10 for additional information regarding the change in unrecognized tax benefits. Concentration of Credit Risk and Major Customers / Suppliers Financial instruments that potentially subject us to concentrations of credit risk consist of accounts and notes receivable, contract assets, and cash. Sales are typically made on credit and we generally do not require collateral. Management performs ongoing credit evaluations of its customers’ financial condition and maintains an allowance for estimated losses. Uncollectible accounts are written off when deemed uncollectible, and accounts receivable are presented net of an allowance for doubtful accounts, which totaled $1.9 million and $0.8 million as of December 31, 2018 and 2017 , respectively. Historically, we have experienced a low level of write-offs related to uncollectible accounts. We maintain the majority of our cash at four depository institutions. As of December 31, 2018 , the aggregate balances in such accounts were $342.3 million . Our balances with these institutions regularly exceed Federal Deposit Insurance Corporation (“FDIC”) insured limits for domestic deposits and various deposit insurance programs covering our deposits in Australia, Germany, Finland, the Netherlands, the United Kingdom, and Vietnam. To manage the related credit exposure, management continually monitors the creditworthiness of the financial institutions where we have deposits. We sell some of our products through a network of unaffiliated distributors. We also sell directly to customers. No customer represented more than 10% of total net sales for the years ended December 31, 2018 , 2017 or 2016 . At December 31, 2018 , and 2017, no customer represented more than 10% of the aggregate balance of accounts and notes receivable and contract assets. We currently purchase finished circuit boards and injection-molded plastic components from suppliers located in the U.S., Mexico and Taiwan. Although we currently obtain many of these components from single source suppliers, we own the injection molded component tooling used in their production. As a result, management believes it could obtain alternative suppliers in most cases without incurring significant production delays. We also purchase small, machined parts from a vendor in Taiwan, custom cartridge components from a proprietary vendor in the U.S., and electronic components from a variety of international and domestic distributors. We believe that there are readily available alternative suppliers in most cases who could consistently meet our needs for these components. We acquire most of our components on a purchase order basis and do not have any significant long-term contracts with suppliers. Fair Value of Financial Instruments We use the fair value framework that prioritizes the inputs to valuation techniques for measuring financial assets and liabilities measured on a recurring basis and for non-financial assets and liabilities when these items are re-measured. Fair value is considered to be the exchange price in an orderly transaction between market participants, to sell an asset or transfer a liability at the measurement date. The hierarchy below lists three levels of fair value based on the extent to which inputs used in measuring fair value are observable in the market. We categorize each of our fair value measurements in one of these three levels based on the lowest level input that is significant to the fair value measurement in its entirety. These levels are: • Level 1 – Valuation techniques in which all significant inputs are unadjusted quoted prices from active markets for assets or liabilities that are identical to the assets or liabilities being measured. • Level 2 – Valuation techniques in which significant inputs include quoted prices from active markets for assets or liabilities that are similar to the assets or liabilities being measured and/or quoted prices for assets or liabilities that are identical or similar to the assets or liabilities being measured from markets that are not active. Also, model-derived valuations in which all significant inputs and significant value drivers are observable in active markets are Level 2 valuation techniques. • Level 3 – Valuation techniques in which one or more significant inputs or significant value drivers are unobservable. Unobservable inputs are valuation technique inputs that reflect our own assumptions about inputs that market participants would use in pricing an asset or liability. We have cash equivalents and investments, which at December 31, 2018 and 2017 , were comprised of money market funds, state and municipal obligations, corporate bonds, and certificates of deposits. See additional disclosure regarding the fair value of our cash equivalents and investments in Note 3. Included in the balance of other assets as of December 31, 2018 and 2017 was $3.6 million and $3.8 million , respectively, related to corporate-owned life insurance policies which are used to fund our deferred compensation plan. We determine the fair value of our insurance contracts by obtaining the cash surrender value of the contracts from the issuer, a Level 2 valuation technique. Our financial instruments also include accounts and notes receivable, accounts payable and accrued liabilities. Due to the short-term nature of these instruments, their fair values approximate their carrying values on the balance sheet. Segment and Geographic Information Our operations are comprised of two reportable segments: the manufacture and sale of CEWs, batteries, accessories, extended warranties and other products and services (the “TASER” segment); and the development, manufacture and sale of software and sensors, which includes the sale of devices, wearables, applications, cloud and mobile products (collectively, the "Software and Sensors" segment). Reportable segments are determined based on discrete financial information reviewed by our Chief Executive Officer who is our chief operating decision maker ("CODM"). We organize and review operations based on products and services, and currently there are no operating segments that are aggregated. We perform an analysis of our reportable segments at least annually. Additional information related to our business segments is summarized in Note 16. For the years ended December 31, 2018 , 2017 and 2016 , net sales by geographic area as well as the percentage relationship to total net sales included in the accompanying statements of operations were as follows (in thousands): Year Ended December 31, 2018 2017 (1) 2016 (1) United States $ 335,310 79.8 % $ 282,810 82.3 % $ 218,757 81.6 % Other Countries 84,758 20.2 60,988 17.7 49,488 18.4 Total $ 420,068 100.0 % $ 343,798 100.0 % $ 268,245 100.0 % (1) Amounts for the years ended December 31, 2017 and 2016 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605. Sales to customers outside of the U.S. are typically denominated in U.S. dollars and are attributed to each country based on the shipping address of the distributor or customer. For the years ended December 31, 2018 , 2017 and 2016 , no individual country outside the U.S. represented more than 10% of net sales. Substantially all of our assets are located in the U.S. Stock-Based Compensation We recognize expense related to stock-based compensation transactions in which we receive services in exchange for equity instruments of the Company. Stock-based compensation expense for RSUs is measured based on the closing fair market value of our common stock on the date of grant. We recognize stock-based compensation expense over the award’s requisite service period on a straight-line basis for time-based RSUs and on a graded basis for RSUs that are contingent on the achievement of performance conditions. We recognize forfeitures as they occur as a reduction to stock-based compensation expense and to additional paid-in-capital. Historically, we have calculated the fair value of stock options using the Black-Scholes-Merton option pricing valuation model, which incorporates various assumptions including expected volatility, expected life, expected dividends and risk-free interest rates. No stock options were awarded from 2012 to 2017. On May 24, 2018 (the “Grant Date”), our stockholders approved the Board of Directors’ grant of 6,365,856 stock option awards to Patrick W. Smith, our CEO (the “CEO Performance Award”). The CEO Performance Award consists of 12 vesting tranches with a vesting schedule based entirely on the attainment of both operational goals (performance conditions) and market capitalization goals (market conditions), assuming continued employment either as the CEO or as both Executive Chairman and Chief Product Officer and service through each vesting date. Stock-based compensation expense associated with the CEO Performance Award is recognized over the requisite service period, which is defined as the longer of the expected achievement period for each pair of market capitalization and operational goals, beginning at the point in time when the relevant operational goal is considered probable of being met. Given the complexity of the award, we utilized Monte Carlo simulations to simulate a range of possible future market capitalizations for the Company over the term of the options. The average of all iterations of the simulation was used as the basis for the valuation and market capitalization goal derived service period for each tranche. Additionally, we applied an illiquidity discount of 9.2% to the valuation because the award specifies a post-exercise holding period of 2.5 years. This discount was estimated using the Finnerty model and reduced by the impact of expected payroll and income taxes due upon exercise of the options, as the related proportion of shares are expected to be sold to satisfy such obligations. Additional assumptions used for the CEO Performance Award and the resulting estimates of weighted-average fair value per share of options granted are as follows: Volatility 47.71% Risk-free interest rate 2.98% Dividend rate — Expected life of options 9.76 years Weighted average grant date fair value of options granted $38.64 The expected life of the options represents the estimated period of time from grant date until exercise; in this case, exercise is assumed to occur at the full contractual term of ten years from grant and is based on input from the CEO and his historical behavior of not exercising vested options. Expected stock price volatility is based on the average of the 9.76-year historical volatility and the implied volatility on 1,080-day call option for the Company. The risk-free interest rate is based on the implied yield available on United States Treasury bill zero-coupon issuances with an equivalent remaining term to the term of the options. We have not paid dividends in the past and do not plan to pay any dividends in the near future. Other than the CEO Performance Award, no options were awarded during the year ended December 31, 2018. No options were awarded during the years ended December 31, 2017 or 2016 . Income per Common Share Basic income per common share is computed by dividing net income by the weighted average number of common shares outstanding during the periods presented. Diluted income per share reflects the potential dilution from outstanding stock options and unvested restricted stock units. The calculation of the weighted average number of shares outstanding and earnings per share are as follows (in thousands except per share data): For the Year Ended December 31, 2018 2017 2016 Numerator for basic and diluted earnings per share: Net income $ 29,205 $ 5,207 $ 17,297 Denominator: Weighted average shares outstanding—basic 56,392 52,726 52,667 Dilutive effect of stock-based awards 1,530 1,172 869 Diluted weighted average shares outstanding 57,922 53,898 53,536 Anti-dilutive stock-based awards excluded 6,757 386 443 Net income per common share: Basic $ 0.52 $ 0.10 $ 0.33 Diluted $ 0.50 $ 0.10 $ 0.32 Recently Issued Accounting Guidance Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”) and Accounting Standards Codification ("ASC") Subtopic 340-40, Other Assets and Deferred Costs - Contracts with Customers ("ASC 340-40"), (collectively, “Topic 606”). On January 1, 2018, we adopted Topic 606 by applying the modified retrospective method of adoption for all contracts that were not substantially completed as of the adoption date. ASU 2014-09 requires entities to recognize revenue through the application of a five-step model, which includes identification of the contract, identification of the performance obligations, determination of the transaction price, allocation of the transaction price to the performance obligations and recognition of revenue as the entity satisfies the performance obligations. Refer to Note 2 for further discussion. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 eliminates the diversity in practice related to the classification of certain cash receipts and payments. ASU 2016-15 designates the appropriate cash flow classification, including requirements to allocate certain components of these cash receipts and payments among operating, investing and financing activities. We adopted ASU 2016-15 effective January 1, 2018, and the adoption of this ASU did not have a material impact on our consolidated financial statements. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740) - Intra-Entity Transfers of Assets Other Than Inventory. ASU 2016-16 requires an entity to recognize income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. This removes the exception to postpone recognition until the asset has been sold to an outside party. We adopted ASU 2016-16 effective January 1, 2018, and the adoption of this ASU did not have a material impact on our consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows - Restricted Cash (Topic 230), which amends the existing guidance relating to the treatment of restricted cash and restricted cash equivalents on the statement of cash flows. We adopted ASU 2016-18 effective January 1, 2018, and retrospectively updated the presentation of our consolidated statements of cash flows to include amounts of restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805) to provide a more robust framework to use in determining when a set of acquired assets and activities is a business. The amendments in ASU 2017-01 provide a screen to determine when a set of acquired integrated assets and activities is not a business, and if the screen is not met it may result in fewer transactions that qualify as a business combination under ASC Topic 805. We adopted ASU 2017-01 effective January 1, 2018, and the adoption of this ASU did not have a material

Revenues

Revenues	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenues Adoption of ASC Topic 606, "Revenue from Contracts with Customers" On January 1, 2018, we adopted Topic 606 using the modified retrospective method applied to those contracts which were not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under Topic 606, while prior period amounts are not adjusted, and continue to be reported in accordance with our historic accounting under ASC 605. We recorded a net increase in stockholders’ equity (retained earnings) of $19.0 million as of January 1, 2018 due to the cumulative impact of adopting Topic 606 on contracts that were not complete as of that date. The areas most significantly impacted were contracts with contingent hardware revenue and the treatment of incremental costs of obtaining contracts with customers. The impact as a result of applying Topic 606 was a net increase to net sales of $5.0 million for the twelve months ended December 31, 2018, and a net decrease to sales, general and administrative expenses of approximately $3.6 million related to the costs of obtaining contracts for the same periods, as compared to what would have been recognized under ASC 605. The impacts to the December 31, 2017 balance sheet of adopting Topic 606 are presented below (in thousands): December 31, 2017 (As reported) Impact of Adoption of Topic 606 on Opening Balance Sheet January 1, 2018 (As adjusted) Accounts and notes receivable, net $ 56,064 $ 28,915 $ 84,979 Contract assets, net — 5,512 5,512 Prepaid expense and other current assets 21,696 2,003 23,699 Total impacted current assets 77,760 36,430 114,190 Deferred income tax assets, net 15,755 (5,158 ) 10,597 Long-term notes receivable 36,877 (12,977 ) 23,900 Other assets 15,366 5,323 20,689 Total impacted assets 145,758 23,618 169,376 Accrued liabilities 23,502 2,512 26,014 Current portion of deferred revenue 70,401 863 71,264 Total impacted current liabilities 93,903 3,375 97,278 Deferred revenue, net of current portion 54,881 1,249 56,130 Total impacted liabilities 148,784 4,624 153,408 Retained earnings 123,185 18,994 142,179 Total impacted stockholders' equity 123,185 18,994 142,179 Total impacted liabilities and stockholders' equity 271,969 23,618 295,587 Nature of Products and Services The following table presents our revenues by primary product and service offering (in thousands): Year Ended December 31, 2018 Year Ended December 31, 2017 (1) TASER Software and Sensors Total TASER Software and Sensors Total TASER 7 $ 7,358 $ — $ 7,358 $ — $ — $ — TASER X26P 70,638 — 70,638 64,426 — 64,426 TASER X2 78,837 — 78,837 81,417 — 81,417 TASER Pulse and Bolt 5,182 — 5,182 4,340 — 4,340 Cartridges 68,258 — 68,258 63,203 — 63,203 Axon Body — 21,883 21,883 — 15,184 15,184 Axon Flex — 6,509 6,509 — 10,083 10,083 Axon Fleet — 12,527 12,527 — 2,954 2,954 Axon Dock — 10,706 10,706 — 9,736 9,736 Axon Evidence and cloud services — 90,291 90,291 — 57,841 57,841 TASER Cam — 3,871 3,871 — 3,358 3,358 Extended warranties 15,753 11,860 27,613 12,426 7,110 19,536 Other 7,089 9,306 16,395 8,700 3,020 11,720 Total $ 253,115 $ 166,953 $ 420,068 $ 234,512 $ 109,286 $ 343,798 (1) Amounts for the year ended December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605. Contract Balances The timing of revenue recognition may differ from the timing of invoicing to customers. We generally have an unconditional right to consideration when we invoice our customers and record a receivable. We record a contract asset when revenue is recognized prior to invoicing, or a contract liability (deferred revenue) when revenue will be recognized subsequent to invoicing. Contract assets generally result from our subscription programs where we satisfy a hardware performance obligation upon shipment to the customer, and the right to the portion of the transaction price allocated to that hardware performance obligation is conditional on our future performance of a SaaS service obligation under the contract. We recognize a portion of the amount allocated to hardware products shipped to the customer as accounts receivable when invoiced to the customer, and record the remaining allocated value as a contract asset as we have generally fulfilled our hardware performance obligation upon shipment. Unbilled accounts receivable expected to be invoiced and collected within twelve months was $17.3 million as of December 31, 2018, and was included in accounts receivable on our consolidated balance sheet. Contract liabilities generally consist of deferred revenue on our subscription programs where we generally invoice customers at the beginning of each annual period and record a receivable at the time of invoicing when there is an unconditional right to consideration. Deferred revenue is comprised mainly of unearned revenue related to our Axon Evidence SaaS platform, secure cloud-based storage, service-type extended warranties, stand-ready obligations in our cartridge programs, and rights to future CEW, camera and related accessories hardware in our subscription programs. Revenue for Axon Evidence and cloud-based storage, our service-type extended warranties and stand-ready cartridge programs is generally recognized on a straight-line basis over the subscription term. Revenue for the rights to future hardware is generally recognized at the point in time the hardware products are shipped to the customer. Payment terms and conditions vary by contract type and geography, but our standard terms are that payments are due within 30 days from the date of invoice. The following table presents our contract assets, contract liabilities and certain information related to these balances as of and for the year ended December 31, 2018 (in thousands): December 31, 2018 Contract assets, net $ 13,960 Contract liabilities (deferred revenue) 181,433 Revenue recognized in the period from: Amounts included in contract liabilities at the beginning of the period 63,475 Contract liabilities (deferred revenue) consisted of the following (in thousands): December 31, 2018 December 31, 2017 (1) Current Long-Term Total Current Long-Term Total Warranty: TASER $ 12,797 $ 16,847 $ 29,644 $ 12,501 $ 18,619 $ 31,120 Software and Sensors 8,273 6,516 14,789 6,293 4,195 10,488 21,070 23,363 44,433 18,794 22,814 41,608 Hardware: TASER 9,355 15,598 24,953 4,164 11,401 15,565 Software and Sensors 20,878 24,685 45,563 16,956 14,781 31,737 30,233 40,283 70,516 21,120 26,182 47,302 Software and Sensors Services 55,713 10,771 66,484 30,487 5,885 36,372 Total $ 107,016 $ 74,417 $ 181,433 $ 70,401 $ 54,881 $ 125,282 December 31, 2018 December 31, 2017 (1) Current Long-Term Total Current Long-Term Total TASER $ 22,152 $ 32,445 $ 54,597 $ 16,665 $ 30,020 $ 46,685 Software and Sensors 84,864 41,972 126,836 53,736 24,861 78,597 Total $ 107,016 $ 74,417 $ 181,433 $ 70,401 $ 54,881 $ 125,282 (1) Amounts as of December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605. Remaining Performance Obligations As of December 31, 2018 , we had approximately $900 million of remaining performance obligations, which included both recognized contract liabilities as well as amounts that will be invoiced and recognized in future periods. The remaining performance obligations are limited only to arrangements that meet the definition of a contract under Topic 606 as of December 31, 2018 . We expect to recognize between 15% - 20% of this balance over the next twelve months, and expect the remainder to be recognized over the following five to seven years, subject to risks related to delayed deployments, budget appropriation or other contract cancellation clauses. Costs to Obtain a Contract We recognize an asset for the incremental costs of obtaining a contract with a customer, which consist primarily of sales commissions. These costs are ascribed to or allocated to the underlying performance obligations in the contract and amortized consistent with the recognition timing of the revenue for the underlying performance obligations. For contract costs related to performance obligations with an amortization period of one year or less, we apply the practical expedient to expense these sales commissions when incurred. These costs are recognized as incurred within sales, general and administrative expenses on the accompanying consolidated statements of operations and comprehensive income. As of December 31, 2018 , our assets for costs to obtain contracts were as follows (in thousands): December 31, 2018 Current deferred commissions (1) $ 7,062 Deferred commissions, net of current portion (2) 15,530 $ 22,592 (1) Current deferred commissions are included within prepaid expenses and other current assets on the accompanying consolidated balance sheet. (2) Deferred commissions, net of current portion, are included in other assets on the accompanying consolidated balance sheet. During the year ended December 31, 2018 , we recognized $5.3 million of amortization related to deferred commissions. These costs are recorded within sales, general and administrative expenses on the accompanying consolidated statements of operations and comprehensive income. Significant Judgments Our contracts with certain municipal government customers may be subject to budget appropriation, other contract cancellation clauses or future periods which are optional. In contracts where the customer’s performance is subject to budget appropriation clauses, we generally consider the likelihood of non-appropriation to be remote when determining the contract term and transaction price. Contracts with other cancellation provisions or optional periods may require judgment in determining the contract term, including the existence of material rights, transaction price and identifying the performance obligations. At times, customers may request changes that either amend, replace or cancel existing contracts. Judgment is required to determine whether the specific facts and circumstances within the contracts require the changes to be accounted for as a separate contract or as a modification. Generally, contract modifications containing additional goods and services that are determined to be distinct and sold at their SSP are accounted for as a separate contract. For contract modifications where both criteria are not met, the original contract is updated and the required adjustments to revenue and contract assets, liabilities, and other accounts will be made accordingly. Our contracts with customers often include promises to transfer multiple products and services to a customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately rather than together may require significant judgment. We consider CEW devices and related accessories, as well as cameras and related accessories, to be separately identifiable from each other as well as from extended warranties on these products and the SaaS subscriptions to Axon Evidence and other cloud services. In contracts where there are timing differences between when we transfer a promised good or service to the customer and when the customer pays for that good or service, we have determined that, with the exception of our TASER 60 installment purchase arrangements, our contracts generally do not include a significant financing component. For the year ended December 31, 2018 , we recorded revenue of $48.2 million , including $1.3 million of interest income, under our TASER 60 plan. For the year ended December 31, 2017, we recorded revenue of $40.7 million including $0.7 million of interest income under our TASER 60 plan. Amounts for the year ended December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606. Judgment is required to determine the SSP for each distinct performance obligation.We analyze separate sales of our products and services as a basis for estimating the SSP of our products and services and then use that SSP as the basis for allocating the transaction price when our products and services are sold together in a contract with multiple performance obligations. In instances where the SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include market conditions, time value of money and other observable inputs. We typically have more than one SSP for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, we may use information such as geographic region and distribution channel in determining the SSP.

Cash, Cash Equivalents and Inve

Cash, Cash Equivalents and Investments	12 Months Ended
	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Investments	Cash, Cash Equivalents and Investments The following tables summarize the Company's cash, cash equivalents, and held-to-maturity investments at December 31, 2018 and December 31, 2017 (in thousands): As of December 31, 2018 Amortized Cost Gross Unrealized Losses Fair Value Cash and Cash Equivalents Short-Term Investments Cash $ 144,095 $ — $ 144,095 $ 144,095 $ — Level 1: Money market funds 205,367 — 205,367 205,367 — Total $ 349,462 $ — $ 349,462 $ 349,462 $ — As of December 31, 2017 Amortized Cost Gross Unrealized Losses Fair Value Cash and Cash Equivalents Short-Term Investments Cash $ 53,459 $ — $ 53,459 $ 53,459 $ — Level 1: Money market funds 20,884 — 20,884 20,884 — Corporate bonds 6,632 (6 ) 6,626 — 6,632 Subtotal 27,516 (6 ) 27,510 20,884 6,632 Level 2: State and municipal obligations 992 — 992 762 230 Subtotal 992 — 992 762 230 Total $ 81,967 $ (6 ) $ 81,961 $ 75,105 $ 6,862

Inventory

Inventory	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventory	Inventory Inventories are stated at the lower of cost and net realizable value. Cost is determined using the weighted average cost of raw materials which approximates the FIFO method and includes allocations of manufacturing labor and overhead. Included in finished goods at December 31, 2018 and December 31, 2017 was $1.4 million and $1.4 million , respectively, of trial and evaluation hardware units. Provisions are made to reduce excess, obsolete or slow-moving inventories to their net realizable value. Inventories consisted of the following at December 31 (in thousands): 2018 2017 Raw materials $ 19,670 $ 20,119 Finished goods 14,093 25,346 Total inventory $ 33,763 $ 45,465

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment consisted of the following at December 31 (in thousands): Estimated Useful Life 2018 2017 Land N/A $ 2,900 $ 2,900 Building and leasehold improvements 3-39 years 19,578 18,383 Production equipment 3-7 years 19,817 19,075 Computers, equipment and software 3-5 years 8,392 6,780 Furniture and office equipment 5-7 years 6,529 5,262 Vehicles 5 years 1,385 1,057 Website development costs 3 years 687 687 Capitalized internal-use software development costs 3 years 3,670 3,695 Construction-in-process N/A 14,820 9,810 Total cost 77,778 67,649 Less: Accumulated depreciation (39,885 ) (36,477 ) Property and equipment, net $ 37,893 $ 31,172 Depreciation and amortization expense related to property and equipment was $4.9 million , $3.4 million and $2.5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, of which $1.4 million , $1.1 million and $0.7 million was included in cost of sales for the respective years.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The changes in the carrying amount of goodwill for the year ended December 31, 2018 were as follows (in thousands): TASER Software and Sensors Total Balance, January 1, 2018 $ 1,453 $ 13,474 $ 14,927 Goodwill acquired — 10,285 10,285 Foreign currency translation adjustments (115 ) (116 ) (231 ) Balance, December 31, 2018 $ 1,338 $ 23,643 $ 24,981 Intangible assets (other than goodwill) consisted of the following (in thousands): December 31, 2018 December 31, 2017 Useful Life Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Amortizable (definite-lived) intangible assets: Domain names 5-10 years $ 3,161 $ (732 ) $ 2,429 $ 3,161 $ (428 ) $ 2,733 Issued patents 4-15 years 2,940 (1,106 ) 1,834 2,697 (913 ) 1,784 Issued trademarks 3-11 years 1,053 (599 ) 454 860 (397 ) 463 Customer relationships 4-8 years 3,701 (880 ) 2,821 1,377 (451 ) 926 Non-compete agreements 3-4 years 540 (439 ) 101 556 (346 ) 210 Developed technology 3-7 years 13,404 (7,081 ) 6,323 13,469 (3,956 ) 9,513 Re-acquired distribution rights 2 years 1,928 (1,813 ) 115 2,133 (711 ) 1,422 Total amortizable 26,727 (12,650 ) 14,077 24,253 (7,202 ) 17,051 Non-amortizable (indefinite-lived) intangible assets: TASER trademark 900 900 900 900 Patents and trademarks pending 958 958 872 872 Total non-amortizable 1,858 1,858 1,772 1,772 Total intangible assets $ 28,585 $ (12,650 ) $ 15,935 $ 26,025 $ (7,202 ) $ 18,823 Amortization expense of intangible assets was $5.7 million , $4.7 million and $0.9 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Estimated amortization for intangible assets with definitive lives for the next five years ended December 31, and thereafter, is as follows (in thousands): 2019 $ 3,463 2020 3,294 2021 2,852 2022 1,211 2023 934 Thereafter 2,323 Total $ 14,077

Other Long-Term Assets

Other Long-Term Assets	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Long-Term Assets	Other Long-Term Assets Other long-term assets consisted of the following at December 31 (in thousands): 2018 2017 Cash surrender value of corporate-owned life insurance policies $ 3,596 $ 3,846 Deferred commissions (1) 15,530 6,803 Restricted cash (2) 661 3,333 Prepaid expenses, deposits and other 3,212 1,384 Total other long-term assets $ 22,999 $ 15,366 (1) Represents assets for the incremental costs of obtaining contracts with customers, which consist primarily of sales commissions. These costs are ascribed to or allocated to the underlying performance obligations in the contracts and amortized consistent with the recognition timing of the revenue for the underlying performance obligations. The amounts as of December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts. In connection with our adoption of Topic 606, we recorded an adjustment of $7.3 million as of January 1, 2018, and of that amount, $5.4 million was recorded within other assets. The adjusted balance of long-term deferred commissions as of January 1, 2018 was $12.2 million . (2) As of December 31, 2018, restricted cash primarily consisted of $0.6 million for a performance guarantee related to an international customer sales contract.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consisted of the following at December 31 (in thousands): 2018 2017 Accrued salaries, benefits and bonus $ 19,063 $ 8,957 Accrued professional, consulting and lobbying fees 4,894 3,870 Accrued warranty expense 898 644 Accrued income and other taxes 4,167 2,558 Other accrued expenses 12,070 7,473 Accrued liabilities $ 41,092 $ 23,502

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating and capital lease obligations We have entered into operating leases for various office space, storage facilities and equipment. As of December 31, 2018 , our leases are for terms ranging from less than one year to five years. Our leases generally contain multi-year renewal options and escalation clauses. Rent expense under all operating leases, including both cancelable and non-cancelable leases, was $4.2 million , $2.9 million and $1.8 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. Future minimum lease payments under non-cancelable leases at December 31, 2018 , are as follows (in thousands): Operating Capital 2019 $ 3,670 $ 40 2020 3,572 36 2021 2,961 — 2022 2,001 — 2023 573 — Thereafter — — Total minimum lease payments $ 12,777 76 Less: Amount representing interest (6 ) Capital lease obligation $ 70 Land Lease Purchase Agreement On December 13, 2018, we entered into a Purchase and Sale Agreement ("PSA") to purchase a leasehold interest to a parcel of land located in Maricopa County, Arizona for a period of 84 years, on which we intend to construct our new headquarters. The purchase price of the land lease was $13.1 million . It is also contemplated that we will prepay the rent under the lease in the amount of $10.9 million . The PSA includes a due diligence period, during which we may terminate and forfeit our initial deposit of $0.2 million . Purchase commitments We routinely enter into cancelable and non-cancelable purchase orders with many of our key vendors. Based on the strategic relationships with many of these vendors, our ability to cancel these purchase orders and maintain a favorable relationship would be limited. As of December 31, 2018 , we had approximately $66.6 million of open purchase orders. Litigation Product Litigation As a manufacturer of weapons and other law enforcement tools used in high-risk field environments, we are often the subject of products liability litigation concerning the use of our products. We are currently named as a defendant in eight lawsuits on the TASER weapons side of our business, all brought by individuals alleging either wrongful death or personal injury in connection with arrests. While the facts vary from case to case, these product liability claims typically allege defective product design, manufacturing, and/or failure to warn. They seek compensatory and sometimes punitive damages, often in unspecified amounts. We continue to aggressively defend all product litigation. As a general rule, it is our policy not to settle suspect injury or death cases. Exceptions are sometimes made where the settlement is strategically beneficial to us. Due to the confidential nature of our litigation strategy and the confidentiality agreements that are executed in the event of a settlement, we do not identify or comment on specific settlements by case or amount. Based on current information, we do not believe that the outcome of any such legal proceeding will have a material effect on our financial position, results of operations, or cash flows. We are self-insured for the first $5.0 million of any product claim made after 2014. No judgment or settlement has ever exceeded this amount in any products case. We continue to maintain product liability insurance coverage, including an insurance policy fronting arrangement, above our self-insured retention with various limits depending on the policy period. Other Litigation We are a defendant in a litigation matter filed by Digital Ally Inc. (“Digital”) in the District of Kansas alleging patent infringement regarding our Axon Signal technology. Digital seeks a judgment of infringement, monetary damages, a permanent injunction, punitive damages and attorneys’ fees and costs. Both fact and expert discovery are now complete. The parties filed motions for summary judgment on January 31, 2019 and briefing is expected to be complete by the end of March 2019. No trial date has yet been set but, if necessary, is expected to occur in Q4 2019 or Q1 2020. We are vigorously defending this litigation. The case has been substantially narrowed based on (1) the district court’s dismissal of all of Digital’s antitrust claims in January 2017; this ruling was affirmed by the Federal Circuit in May 2018 and the U.S. Supreme Court denied review; (2) the district court’s dismissal of Digital’s ‘292 patent from the litigation with prejudice in March 2018, and Digital’s execution of a covenant not to sue Axon on that patent on existing Axon products; and (3) Digital’s dismissal of certain inconsistent claims in the ‘452 patent, leaving only one independent claim for resolution by the court. We believe the ‘452 patent is both invalid and not infringed, and we do not believe it is probable that we will incur a material loss. The October 2018 litigation filed by former VIEVU, LLC employee Amani Kiogora in King County, Washington has been dismissed against Axon. Safariland, LLC has accepted the defense and indemnification of VIEVU for any alleged commissions owed. The April 2016 arbitration claim filed by Antoine di Zazzo, our former distributor in France, was successfully resolved in our favor in December 2018, including an award of fees and costs. The litigation information in this note is current through the date of these financial statements. U.S. Federal Trade Commission Investigation In June 2018 we received a letter from the U.S. Federal Trade Commission (“FTC”) with respect to its non-public investigation into our acquisition of VIEVU, LLC in May 2018. The FTC requested that we provide certain information and documentation relating to the acquisition. We are cooperating with the investigation. General From time to time, we are notified that we may be a party to a lawsuit or that a claim is being made against us. It is our policy to not disclose the specifics of any claim or threatened lawsuit until the summons and complaint are actually served on us. After carefully assessing the claim, and assuming we determine that we are not at fault or we disagree with the damages or relief demanded, we vigorously defend any lawsuit filed against us. We record a liability when losses are deemed probable and reasonably estimable. When losses are deemed reasonably possible but not probable, we determine whether it is possible to provide an estimate of the amount of the loss or range of possible losses for the claim, if material for disclosure. In evaluating matters for accrual and disclosure purposes, we take into consideration factors such as our historical experience with matters of a similar nature, the specific facts and circumstances asserted, the likelihood of our prevailing, the availability of insurance, and the severity of any potential loss. We reevaluate and update accruals as matters progress over time. Based on our assessment of outstanding litigation and claims as of December 31, 2018 , we have determined that it is not reasonably possible that these lawsuits will individually, or in the aggregate, materially affect our results of operations, financial condition or cash flows. However, the outcome of any litigation is inherently uncertain and there can be no assurance that any expense, liability or damages that may ultimately result from the resolution of these matters will be covered by our insurance or will not be in excess of amounts recognized or provided by insurance coverage and will not have a material adverse effect on our operating results, financial condition or cash flows. Off-Balance Sheet Arrangements Under certain circumstances, we use letters of credit and surety bonds to guarantee our performance under various contracts, principally in connection with the installation and integration of our Axon cameras and related technologies. Certain of our letters of credit contracts and surety bonds have stated expiration dates, with others being released as the contractual performance terms are completed. We expect to fulfill all contractual performance obligations related to outstanding guarantees. At December 31, 2018 , we had outstanding letters of credit of approximately $3.1 million , which are expected to expire in May 2019 and September 2021. Additionally, we had approximately $14.1 million of outstanding surety bonds at December 31, 2018 , with $0.4 million expiring in 2019, $0.7 million expiring in 2020, $2.3 million expiring in 2021, $3.1 million expiring in 2022 and the remaining $7.6 million expiring in 2023.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act made broad and complex changes to the U.S. tax code including, but not limited to, reducing the U.S. federal corporate tax rate from 35 percent to 21 percent for tax years beginning in 2018 and requiring companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred. The Tax Act established certain new provisions which are applicable to us including (1) creating a new provision designed to tax global intangible low-tax income ("GILTI"); (2) establishing a deduction for foreign derived intangible income ("FDII"); (3) repealing the domestic production activity deduction; and (4) establishing new limitations on certain executive compensation. During the year ended December 31, 2017, we recorded additional net tax expense of $7.6 million for the impact of the Tax Act using the current available information and technical guidance on the interpretations of the Tax Act. As permitted by SEC Staff Accounting Bulletin 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, we recorded provisional estimates and have subsequently finalized our accounting analysis based on the guidance, interpretations, and data available as of December 31, 2018. We recorded additional tax expense of $0.3 million during the three months ended December 31, 2018 upon finalization of our accounting analysis. Income before income taxes included the following components for the years ended December 31 (in thousands): 2018 2017 2016 United States $ 25,751 $ 14,978 $ 38,414 Foreign 2,353 783 (6,917 ) Total $ 28,104 $ 15,761 $ 31,497 Significant components of the provision for income taxes are as follows for the years ended December 31 (in thousands): 2018 2017 2016 Current: Federal $ 4,900 $ 6,039 $ 16,346 State 1,377 1,263 1,534 Foreign 228 656 1,050 Total current 6,505 7,958 18,930 Deferred: Federal (8,382 ) 4,539 (4,145 ) State (364 ) (1,631 ) (977 ) Foreign (3 ) (78 ) (45 ) Total deferred (8,749 ) 2,830 (5,167 ) Tax impact of unrecorded tax benefits liability 1,143 (234 ) 437 Provision for income taxes (Income tax benefit) $ (1,101 ) $ 10,554 $ 14,200 A reconciliation of our effective income tax rate to the federal statutory rate follows for the years ended December 31 (in thousands): 2018 2017 2016 Federal income tax at the statutory rate $ 5,902 $ 5,518 $ 11,024 State income taxes, net of federal benefit (215 ) 339 889 Difference between statutory and foreign tax rates 7 (560 ) 1,521 Permanent differences (1) 725 300 (457 ) Executive compensation limitation 1,167 — — Research and development (6,908 ) (2,380 ) (1,928 ) Return to provision adjustment 1,780 23 327 Change in liability for unrecognized tax benefits 1,768 7 700 Excess stock-based compensation benefit (2) (8,907 ) (1,819 ) (77 ) Change in valuation allowance 1,984 1,949 1,779 Tax effects of intercompany transactions 1,004 (277 ) 630 Adjustments to deferred tax assets, net resulting from enactment of new tax law (3) — 7,601 — Other 592 (147 ) (208 ) Provision for income taxes (Income tax benefit) $ (1,101 ) $ 10,554 $ 14,200 Effective tax rate (3.9 )% 66.9 % 45.1 % (1) Permanent differences include certain expenses that are not deductible for tax purposes including meals and entertainment, certain transaction costs, lobbying fees, and unfavorable income as a result of GILTI offset by favorable items including the domestic production activities deduction, for tax years 2017 and 2016, and a deduction for FDII for 2018. (2) For the years ended December 31, 2018 and 2017 , the provision for income taxes included $8.9 million and $1.8 million , respectively, of benefits resulting from excess stock-based compensation that were recorded as a decrease in the provision for income taxes. For the year ended December 31, 2016, we included $1.4 million of benefits resulting from excess stock-based compensation that were recorded as increases to additional paid-in capital in the consolidated statement of changes in stockholders' equity. (3) The adjustment to deferred tax assets of $7.6 million was a result of the impact of changes in the U.S. federal effective tax rate, as well as a reduction of the stock-based compensation deferred tax asset due to expected permanent limitations on its deductibility for certain key executives under the Tax Act. Significant components of our deferred income tax assets and liabilities are as follows at December 31 (in thousands): 2018 2017 Deferred income tax assets: Net operating loss carryforward $ 2,347 $ 3,691 Deferred revenue 13,304 9,442 Deferred compensation 858 1,109 Inventory reserve 1,294 702 Non-qualified and non-employee stock option expense 3,758 3,704 Capitalized research and development — 485 Amortization 412 — Research and development tax credit carryforward 5,193 3,817 Reserves, accruals, and other 3,094 1,921 Total deferred income tax assets 30,260 24,871 Deferred income tax liabilities: Depreciation (2,195 ) (2,027 ) Amortization (57 ) (1,398 ) Other (1,232 ) (256 ) Total deferred income tax liabilities (3,484 ) (3,681 ) Net deferred income tax assets before valuation allowance 26,776 21,190 Valuation allowance (7,429 ) (5,435 ) Net deferred income tax assets $ 19,347 $ 15,755 We have $2.5 million of state net operating losses (“NOLs”) which expire at various dates between 2029 and 2036 . We also have a federal NOL of $1.5 million which expires in 2036 , and is subject to limitation under Internal Revenue Code (“IRC”) Section 382. We have $0.1 million of federal R&D credits, which expire in 2024 and 2027, and are also subject to limitation under IRC Section 382. We have $9.7 million of Arizona R&D credits carrying forward, which expire at various dates between 2019 and 2033 . In the U.K., Canada, and Germany, we have $8.9 million , $1.4 million , and $0.1 million of NOLs, respectively, which expire at various dates or may be carried forward indefinitely. In preparing our consolidated financial statements, management has assessed the likelihood that deferred income tax assets will be realized from future taxable income. In evaluating the ability to recover its deferred income tax assets, management considers all available evidence, positive and negative, including our operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction by jurisdiction basis. A valuation allowance is established if it is determined that it is more likely than not that some portion or all of the net deferred income tax assets will not be realized. Management exercises significant judgment in determining our provisions for income taxes, our deferred income tax assets and liabilities, and our future taxable income for purposes of assessing our ability to utilize any future tax benefit from our deferred income tax assets. As of December 31, 2018, we continue to demonstrate positive income in the U.S. federal and state tax jurisdictions; however, we have Arizona R&D tax credits expiring unutilized each year. Therefore, management has concluded that it is more likely than not that our Arizona R&D deferred tax asset will not be realized. As of December 31, 2018 , we have cumulative pre-tax losses in Australia, the U.K., and Canada, which limits the ability to consider other subjective evidence, such as projections for future growth. On the basis of this evaluation, a full valuation allowance has been recorded for these jurisdictions. The amount of the deferred tax asset considered realizable; however, could be adjusted in future periods if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as projections for growth. We consider the undistributed earnings of certain non-U.S. subsidiaries to be indefinitely reinvested outside of the United States on the basis of estimates that future domestic cash generation will be sufficient to meet future domestic cash needs and our specific plans for reinvestment of those subsidiary earnings. We project that our foreign earnings will be utilized offshore for working capital and future foreign growth. The determination of the unrecognized deferred tax liability on those undistributed earnings is not practicable due to our legal entity structure and the complexity of U.S. and local country tax laws. If we decide to repatriate the undistributed foreign earnings, we will need to recognize the income tax effects in the period we change our assertion on indefinite reinvestment. We complete R&D tax credit studies for each year that an R&D tax credit is claimed for federal, Arizona, and California income tax purposes. Management has made the determination that it is more likely than not that the full benefit of the R&D tax credit will not be sustained on examination and recorded a liability for unrecognized tax benefits of $5.2 million as of December 31, 2018 . In addition, management accrued approximately $0.1 million for estimated uncertain tax positions related to certain federal income tax liabilities. Should the unrecognized tax benefit of $5.3 million be recognized, our effective tax rate would be favorably impacted. The following table presents a roll forward of our liability for unrecognized tax benefits, exclusive of accrued interest, as of December 31 (in thousands): 2018 2017 2016 Balance, beginning of period $ 4,243 $ 4,050 $ 3,396 Increase in previous year tax positions 213 379 206 Increase in current year tax positions 1,982 587 448 Decrease due to lapse of statutes of limitations (380 ) (773 ) — Balance, end of period $ 6,058 $ 4,243 $ 4,050 Federal income tax returns for 2015 through 2017 remain open to examination by the U.S. Internal Revenue Service (the “IRS”), while state and local income tax returns for 2014 through 2017 also generally remain open to examination by state taxing authorities. The 2004 through 2013 income tax returns are only open to the extent that net operating loss or other tax attributes carrying forward from those years were utilized in 2014 through 2017. The foreign tax returns for 2014 through 2017 also generally remain open to examination. Our U.S. federal income tax return for fiscal year 2016 is currently under audit by the Internal Revenue Service. We recognize interest and penalties related to unrecognized tax benefits within the provision (benefit) for income tax expense line in the accompanying consolidated statements of operations and comprehensive income. As of December 31, 2018 and 2017, we had accrued interest of $0.1 million .

Line of Credit

Line of Credit	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Line of Credit	Line of Credit We have a $100.0 million unsecured revolving line of credit with a domestic bank, of which $10.0 million is available for letters of credit. The credit agreement matures on December 31, 2021 and has an accordion feature which allows for an increase in the total line of credit up to $100.0 million , subject to certain conditions, including the availability of additional bank commitments. At December 31, 2018 and 2017 , there were no borrowings under the line. Under the terms of the line of credit, available borrowings are reduced by outstanding letters of credit. As of December 31, 2018 , we had letters of credit outstanding of approximately $3.1 million under the facility and available borrowing of $96.9 million . Advances under the line of credit bear interest at LIBOR plus 1.0 to 1.5% per year determined in accordance with a pricing grid based on our funded debt to earnings before interest, taxes, depreciation and amortization ("EBITDA") ratio. We are required to comply with a maximum funded debt to EBITDA ratio of no greater than 2.50 to 1.00 based upon a trailing four fiscal quarter period. At December 31, 2018 , our funded debt to EBITDA ratio was 0.001 to 1.00.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock and Preferred Stock We have authorized the issuance of two classes of stock designated as “common stock” and “preferred stock,” each having a par value of $0.00001 per share. We are authorized to issue 200 million shares of common stock and 25 million shares of preferred stock. Follow-On Offering In May 2018, we sold 4,645,000 shares of our common stock, which included 645,000 shares pursuant to the full exercise of the underwriters' option to purchase additional shares, in an underwritten public offering at a price of $53.00 per share, which resulted in gross proceeds of $246.2 million . Net proceeds after deducting fees, commissions, and other expenses related to the offering were $234.0 million . CEO Performance Award On May 24, 2018, our stockholders approved the CEO Performance Award of 6,365,856 stock option awards. The CEO Performance Award consists of 12 vesting tranches with a vesting schedule based entirely on the attainment of both operational goals (performance conditions) and market capitalization goals (market conditions), assuming continued employment either as the CEO or as both Executive Chairman and Chief Product Officer and service through each vesting date. Each of the 12 vesting tranches of the CEO Performance Award have a 10-year contractual term and will vest upon certification by the Compensation Committee of the Board of Directors that both (i) the market capitalization goal for such tranche, which begins at $2.5 billion for the first tranche and increases by increments of $1.0 billion thereafter, and (ii) any one of the following eight operational goals focused on revenue or eight operational goals focused on Adjusted EBITDA have been met for the previous four consecutive fiscal quarters. Adjusted EBITDA for purposes of the CEO Performance Award ("Adjusted EBITDA (CEO Performance Award)") is defined as net income (loss) attributable to common stockholders before interest expense, investment interest income, provision (benefit) for income taxes, depreciation and amortization, and stock-based compensation expense. Eight Separate Revenue Goals (1) (in thousands) Eight Separate Adjusted EBITDA (CEO Performance Award) Goals (in thousands) Goal #1, $710,058 Goal #9, $125,000 Goal #2, $860,058 Goal #10, $155,000 Goal #3, $1,010,058 Goal #11, $175,000 Goal #4, $1,210,058 Goal #12, $190,000 Goal #5, $1,410,058 Goal #13, $200,000 Goal #6, $1,610,058 Goal #14, $210,000 Goal #7, $1,810,058 Goal #15, $220,000 Goal #8, $2,010,058 Goal #16, $230,000 (1) In connection with the business acquisition that was completed during the three months ended June 30, 2018 (Note 15), the revenue goals have been adjusted for the acquiree's Target Revenue, as defined in the CEO Performance Award agreement. As of December 31, 2018 , the following operational goals were considered probable of achievement: • Total revenue of $710.1 million ; and • Adjusted EBITDA (CEO Performance Award) of $125.0 million . Stock-based compensation expense associated with the CEO Performance Award is recognized over the longer of the expected achievement period for each pair of market capitalization and operational goals, beginning at the point in time when the relevant operational goal is considered probable of being met. The probability of meeting an operational goal and the expected achievement point in time for meeting a probable operational goal are based on a subjective assessment of our forward-looking financial projections, taking into consideration statistical analysis. Even though no tranches of the CEO Performance Award vest unless a market capitalization and a matching operational goal are both achieved, stock-based compensation expense is recognized when an operational goal is considered probable of achievement regardless of whether a market capitalization goal is actually achieved. Additionally, stock-based compensation represents a non-cash expense and is recorded in sales, general, and administrative operating expense on our consolidated statements of operations and comprehensive income. The first two market capitalization goals have been achieved as of December 31, 2018. However, none of the stock options granted under the CEO Performance Award have vested thus far as the operational goals have not yet been achieved as of December 31, 2018 . As there are two operational goals considered probable of achievement, we recorded stock-based compensation expense of $3.3 million related to the CEO Performance Award from the Grant Date through December 31, 2018 . The number of stock options that would vest related to the two tranches is approximately 1.1 million shares. As of December 31, 2018 , we had $42.0 million of total unrecognized stock-based compensation expense for the operational goals that were considered probable of achievement, which will be recognized over a weighted-average period of 7.2 years. As of December 31, 2018 , we had unrecognized stock-based compensation expense of $200.7 million for the operational goals that were considered not probable of achievement. Stock-based Compensation Plans We have historically utilized stock-based compensation, consisting of RSUs and stock options, for key employees and non-employee directors as a means of attracting and retaining quality personnel. Service-based grants generally have a vesting period of 3 to 5 years and a contractual maturity of ten years . Performance-based grants generally have vesting periods ranging from 1 to 5 years and a contractual maturity of ten years . On March 29, 2018, our Board of Directors approved the 2018 Stock Incentive Plan (the “2018 Plan"), which was subsequently approved by stockholders at the Annual Meeting of Stockholders on May 24, 2018. Under the 2018 Plan, we reserved for future grants: (i) 1.0 million shares of common stock, plus (ii) the number of shares of common stock that were authorized but unissued under our 2016 Stock Incentive Plan (the “2016 Plan”) and all prior Company equity plans as of the effective date of the 2018 Plan, and (iii) the number of shares of stock that have been granted under the prior plans that either terminate, expire or lapse for any reason after the effective date of the 2016 Plan. As of December 31, 2018 , approximately 1.7 million shares remain available for future grants. Shares issued upon exercise of stock awards from these plans have historically been issued from our authorized unissued shares. Performance-based stock awards We have issued performance-based stock options and performance-based RSUs, the vesting of which is generally contingent upon the achievement of certain performance criteria related to our operating performance, as well as successful and timely development and market acceptance of future product introductions. In addition, certain of the performance RSUs have additional service requirements subsequent to the achievement of the performance criteria. Compensation expense is recognized over the requisite service period, which is defined as the longest explicit, implicit or derived service period based on management’s estimate of the probability of the performance criteria being satisfied, adjusted at each balance sheet date. Restricted Stock Units The following table summarizes RSU activity for the years ended December 31 (number of units and aggregate intrinsic value in thousands): 2018 2017 2016 Number of Units Weighted Average Grant-Date Fair Value Number of Units Weighted Average Grant-Date Fair Value Number of Units Weighted Average Grant-Date Fair Value Units outstanding, beginning of year 2,348 $ 23.47 1,330 $ 20.40 1,139 $ 19.30 Granted 381 46.06 1,731 24.59 718 19.75 Released (772 ) 23.85 (519 ) 18.85 (414 ) 15.91 Forfeited (302 ) 24.73 (194 ) 24.61 (113 ) 21.65 Units outstanding, end of year 1,655 28.34 2,348 23.47 1,330 20.40 Aggregate intrinsic value at year end $ 72,406 Aggregate intrinsic value represents our closing stock price on the last trading day of the period, which was $43.75 per share at December 31, 2018 , multiplied by the number of RSUs. The fair value as of the respective vesting dates of RSUs that vested during the year ended December 31, 2018 was $36.6 million . Certain RSUs that vested in 2018 were net-share settled, such that we withheld shares with value equivalent to the employees’ minimum statutory obligation for the applicable income and other employment taxes, and remitted the cash to the appropriate taxing authorities. Total shares withheld during 2018 were 0.2 million and had a value of approximately $7.8 million on their respective vesting dates as determined by the closing stock price of our stock. Payments for the employees’ tax obligations are reflected as a financing activity within the statement of cash flows. These net-share settlements had the effect of share repurchases by us as they reduced the amount of shares that would have otherwise been issued as a result of the vesting. In 2018 , 2017 and 2016 , we granted approximately 94,000 , 353,000 and 79,000 performance-based RSUs, respectively (included in the table above). Certain of the performance-based RSUs outstanding as of December 31, 2018 can vest with a range of shares earned being between 0% and 200% of the targeted shares granted, depending on the final achievement of pre-determined performance criteria as of the vesting date. As of December 31, 2018 , the performance criteria had been met for approximately 4,000 of the 0.4 million performance-based RSUs outstanding. We recognized $4.8 million , $2.5 million and $2.1 million of compensation expense related to performance-based RSUs during the years ended December 2018 , 2017 and 2016 , respectively. As of December 31, 2018 , there was $35.9 million in unrecognized compensation costs related to RSUs under our stock plans. We expect to recognize the cost related to the RSUs over a weighted average period of 2.26 years . Stock Option Activity The following table summarizes stock option activity for the years ended December 31 (number of options in thousands): 2018 2017 2016 Number of Options Weighted Average Exercise Price Number of Options Weighted Average Exercise Price Number of Options Weighted Average Exercise Price Options outstanding, beginning of year 804 $ 4.99 1,008 $ 5.40 1,103 $ 5.37 Granted 6,366 28.58 — — — — Exercised (664 ) 5.09 (198 ) 6.99 (95 ) 5.02 Expired / terminated (48 ) 4.55 (6 ) 8.32 — — Options outstanding, end of year 6,458 28.24 804 4.99 1,008 5.40 Options exercisable, end of year 92 4.45 775 5.00 977 5.42 6.4 million stock options were granted in 2018 and none were granted in 2017 or 2016 . The total intrinsic value of options exercised was $28.5 million , $3.2 million and $2.0 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. The intrinsic value for options exercised was calculated as the difference between the exercise price of the underlying stock option awards and the market price of our common stock on the date of exercise. Of the total stock options exercised during the year ended December 31, 2018, 0.3 million were exercised and the shares then sold by our CEO in connection with our follow-on offering. The CEO surrendered already owned shares to cover the exercise price of the option exercises. The option exercises were net-share settled such that we withheld shares with value equivalent to the CEO’s minimum statutory obligation for the applicable income and other employment taxes, and remitted the cash to the appropriate taxing authorities. Total shares withheld for tax purposes and surrendered to cover the option exercises were 0.1 million and 29,854 , respectively, and had a value of $6.2 million and $1.6 million , respectively, on the exercise date as determined by the closing stock price on that day. Payments for the employee's tax obligations are reflected as a financing activity within the statement of cash flows. We recorded a liability for the tax withholding to be paid by us as a reduction to additional paid-in capital. The following table summarizes information about stock options that were fully vested or expected to vest as of December 31, 2018 (number of options in thousands): Options Outstanding Options Exercisable Range of Exercise Price Number of Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Number of Options Exercisable Weighted Weighted Average Remaining Contractual Life (Years) $4.20 - $6.30 92 $ 4.45 1.54 92 $ 4.45 1.54 The aggregate intrinsic value of options outstanding and options exercisable at December 31, 2018 was $3.6 million and $3.6 million , respectively. Aggregate intrinsic value represents the difference between the exercise price of the underlying stock option awards and the closing market price of our common stock of $43.75 on December 31, 2018 . At December 31, 2018 , we had 6,365,856 unvested options outstanding with a weighted average exercise price of $28.58 per share, weighted average grant-date fair value of $38.64 per share and weighted average remaining contractual life of 9.8 years . The aggregate intrinsic value of unvested options at December 31, 2018 was $96.6 million . We granted approximately 1.0 million performance-based stock options (included in the table above) from 2008 through 2011. As of December 31, 2018 , approximately 0.1 million performance-based stock options are outstanding and exercisable. The aggregate grant-date fair value of the 0.1 million performance-based stock options vested as of December 31, 2018 was approximately $3.6 million . Stock-based Compensation Expense We account for stock-based compensation using the fair-value method. Reported stock-based compensation was classified as follows for the years ended December 31 (in thousands): 2018 2017 2016 Cost of product and service sales $ 511 $ 508 $ 342 Sales, general and administrative expenses 12,710 9,047 5,707 Research and development expenses 8,658 6,055 3,320 Total stock-based compensation expense $ 21,879 $ 15,610 $ 9,369 Income tax benefit $ 4,049 $ 5,791 $ 3,526 Stock Repurchase In February 2016, our Board of Directors authorized a stock repurchase program to acquire up to $50.0 million of our outstanding common stock subject to stock market conditions and corporate considerations. During the year ended December 31, 2016, we purchased, under a Rule 10b5-1 plan, approximately 1.8 million common shares for a total cost of approximately $33.7 million , or a weighted average cost of $18.90 per share. As of December 31, 2018 and 2017, $16.3 million remained available under the plan for future purchases. We suspended our 10b5-1 plan during 2016, and any future purchases will be discretionary. Stock Incentive Plan In February 2019, our shareholders approved a new stock incentive plan (the “2019 Plan”) authorizing an additional 6.0 million shares, plus remaining available shares under prior plans, for issuance under the new plan. eXponential Stock Performance Plan On February 12, 2019 , our shareholders approved the 2019 Plan, which was adopted by the Board of Directors to reserve a sufficient number of shares to facilitate our eXponential Stock Performance Plan (“XSPP”) and grants of eXponential Stock Units (“XSUs”) under the plan. Pursuant to the XSPP, all eligible full-time U.S. employees were granted an award of 60 XSUs in January 2019, and certain employees had the opportunity to elect to receive a percentage of the value of their target compensation over the next nine years (2019-2027) in the form of additional XSUs. For employees who elected to receive XSUs, the XSU grants were made as an up front, lump sum grant in January 2019, and are intended to replace that portion of the target compensation they elected to receive in the form of XSUs for the next nine years. Accordingly, their go forward target compensation will be reduced until 2027 by the amount of such compensation that the employees elected to receive in the form of the January 2019 XSU grants. A total of approximately 5.1 million XSUs were granted in January 2019. The XSUs are grants of restricted stock units, each with a term of approximately nine years, that vest in 12 equal tranches. Each of the 12 tranches will vest upon certification by the Compensation Committee of the Board of Directors that both (i) the market capitalization goal for such tranche, which begins at $2.5 billion for the first tranche and increases by increments of $1.0 billion thereafter, and (ii) any one of eight operational goals focused on revenue or eight operational goals focused on Adjusted EBITDA have been met for the previous four consecutive fiscal quarters. The XSPP contains an anti-dilution provision, which is used to calculate a maximum number of shares outstanding for purposes of determining achievement of the market capitalization goals whereby the maximum number of shares used to calculate the market capitalization goal is calculated by organically growing the current number of shares outstanding by 3% per year (the "XSU Maximum"). Any shares of Stock issued to Patrick W. Smith upon the exercise of the stock options granted to Mr. Smith under the CEO Performance Award shall increase the XSU Maximum. The XSU Maximum shall also be adjusted for acquisitions, spin-offs or other changes in the number of outstanding shares of common stock, if such changes have a corresponding adjustment on the market capitalization goals. The market capitalization and operational goals are identical to the CEO Performance Award, except for the number of shares that are used to calculate the market capitalization goals if shares outstanding exceed the XSU Maximum. Additionally, because the grant date is different than that of the CEO Performance Award, the measurement period for market capitalization is not identical.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions We subscribe to a mobile collaboration software suite from Quip, a company that was co-founded and managed by Bret Taylor, a member of our Board of Directors. In April 2016, Quip was acquired by Salesforce, and subsequent to the acquisition, we continue to consider Quip a related party. In November 2017, Mr. Taylor was appointed to President and Chief Product Officer of Salesforce. We now consider the consolidated Salesforce entity to be a related party. The cost to subscribe to various cloud-based hosting arrangements from Salesforce and Quip was $1.8 million , $1.2 million and $0.8 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Amounts owed as of December 31, 2018 and 2017 were negligible.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans We have a defined contribution profit sharing 401 (k) plan for eligible employees, which is qualified under Sections 401 (a) and 401 (k) of the Internal Revenue Code of 1986, as amended. Employees are entitled to make tax-deferred contributions of up to the maximum allowed by law of their eligible compensation. We also have a non-qualified deferred compensation plan for certain executives, key employees and non-employee directors through which participants may elect to postpone the receipt and taxation of a portion of their compensation, including stock-based compensation, received from us. The non-qualified deferred compensation plan allows eligible participants to defer up to 80% of their base salary and up to 100% of other types of compensation. The plan also allows for matching and discretionary employer contributions. Employee deferrals are deemed 100% vested upon contribution. Distributions from the plan generally commence upon retirement, death, separation of service, specified date or upon the occurrence of an unforeseeable emergency. Distributions can be paid in a variety of forms from lump sum to installments over a period of years. Participants in the plan are entitled to select from a wide variety of investments available under the plan and are allocated gains or losses based upon the performance of the investments selected by the participant. All gains or losses are allocated fully to plan participants and we do not guarantee a rate of return on deferred balances. Assets related to this plan consist of corporate-owned life insurance contracts and are included in other assets in the consolidated balance sheets. Participants have no rights or claims with respect to any plan assets and any such assets are subject to the claims of our general creditors. Contributions to the plans are made by both the employee and us. Our contributions are based on the level of employee contributions and are immediately vested. Our matching contributions to the 401(k) plan for the years ended December 31, 2018 , 2017 and 2016 , were approximately $3.2 million , $2.5 million and $1.6 million , respectively. Future matching or profit sharing contributions to the plans are at our sole discretion.

Business Acquisitions

Business Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Acquisitions	Business Acquisitions Dextro, Inc. On February 8, 2017, we acquired all of the outstanding common stock of Dextro for a total purchase price of $7.5 million . Dextro's technology provides one of the first computer-vision and deep learning systems to make the visual contents in video searchable in real time. This technology will allow law enforcement agencies and departments to quickly isolate and analyze critical seconds of footage from massive amounts of video data. The technology acquired, along with the Dextro employees that joined Axon, were key additions to the Axon Artificial Intelligence team. The purchase price of $7.5 million consisted primarily of cash, net of cash acquired, and contingent consideration of $1.0 million representing potential earn-outs to former stockholders based on predetermined future metrics. As of December 31, 2018, 0.6 million was earned and paid relative to the former stockholder earn-out provisions. We also agreed to additional earn-out provisions to former Dextro employees totaling approximately $1.4 million based, in part, on predetermined future metrics. The additional earn-outs were not included as part of the purchase price and are being expensed as compensation for the employees in the period earned. The major classes of assets and liabilities to which we allocated the purchase price were as follows (in thousands): Accounts receivable $ 12 Property and equipment 46 Developed technology 5,800 Goodwill 2,703 Deferred income tax liabilities, net (1,074 ) Total purchase price $ 7,487 We assigned the goodwill to the Software and Sensors segment. Identifiable definite-lived intangible assets were assigned a total weighted average amortization period of 3.4 years. Dextro has been included in our consolidated results of operations subsequent to the acquisition date. Pro forma results of operations for Dextro have not been presented because they are not material to the consolidated results of operations. In connection with the acquisition, we incurred and expensed costs of approximately $0.2 million , which included legal, accounting and other third-party expenses related to the transaction. Breon Enterprises On July 1, 2017, we acquired certain tangible and intangible assets from Breon, which was our distributor in the Australia region. This transaction, which was accounted for as a business combination under ASC 805, is intended to expand our growth across Australia and surrounding regions by growing our in-country sales and support team. The purchase price of $4.2 million was paid in full in July 2017. As of the acquisition date, we had a $2.2 million pre-existing accounts receivable balance from Breon for our sales of goods and services to Breon prior to the acquisition date. This receivable balance was cash settled in full separately from the business combination at its book value, which was considered to be the fair value due to the short-term nature of the receivable. The major classes of assets to which we allocated the purchase price were as follows (in thousands): Re-acquired distribution rights $ 2,100 Customer relationships 400 Goodwill 1,650 Total purchase price $ 4,150 We assigned $0.8 million of the goodwill to each of the TASER and Software and Sensors segments. The assignment of goodwill was based on our estimate of how the acquired assets would contribute cash flows to us over time. Identifiable definite-lived intangible assets were assigned a total weighted average amortization period of 2.1 years. Breon has been included in our consolidated results of operations subsequent to the acquisition date. Pro forma results of operations for Breon have not been presented because they are not material to the consolidated results of operations. Costs related to the acquisition were expensed as incurred and were considered insignificant. VIEVU On May 3, 2018, we acquired all of the outstanding ownership interests of VIEVU, a public safety camera and cloud-based evidence management system provider for law enforcement agencies. The estimated purchase price of $17.6 million consisted of $5.0 million in cash, net of cash acquired of $0.1 million , and $2.4 million , or 58,843 shares, of our common stock issued to VIEVU’s parent company, Safariland, LLC (“Safariland”). Additionally, the purchase price consisted of contingent consideration of up to $6.0 million , or 141,226 additional shares of common stock, if certain conditions relating to retention of certain VIEVU customers are met as of the first and second anniversaries of the acquisition date. The fair value of the contingent consideration as of the acquisition date was $5.8 million . The purchase price also included the fair value of a long-term Product Development and Supplier Agreement (the “Supply Agreement”) with Safariland, pursuant to which Safariland will be our preferred provider of holsters for our CEW products. The estimated fair value of the Supply Agreement as of the acquisition date was $4.5 million , a portion of which was recorded within accrued liabilities and the remaining portion recorded within other long-term liabilities. Pursuant to ASC 805, the acquisition of VIEVU has been accounted for as a business combination, under the acquisition method of accounting, which resulted in acquired assets and assumed liabilities being measured at their estimated fair values as of the acquisition date. As of the acquisition date, goodwill was measured as the excess of consideration transferred, which is also generally measured at fair value, over the net acquisition date fair values of the assets acquired and liabilities assumed. Goodwill includes the value of intangible assets that do not qualify for separate recognition as well as strategic benefits we expect to realize from the acquisition. $5.2 million of the acquired goodwill is expected to be deductible for tax purposes. The major classes of assets and liabilities to which we have allocated the purchase price were as follows (in thousands): Accounts receivable $ 1,776 Inventory 2,626 Prepaid expenses and other assets 362 Property and equipment 459 Contract assets 1,472 Intangible assets 4,510 Goodwill 10,285 Accounts payable and accrued liabilities (3,345 ) Deferred revenue (543 ) Total purchase price $ 17,602 We have assigned the goodwill to the Software and Sensors segment. Identifiable definite-lived intangible assets were assigned a total weighted average amortization period of 5.1 years. VIEVU has been included in our consolidated results of operations subsequent to the acquisition date. Revenue included in our consolidated financial statements from the acquisition date through December 31, 2018 was $6.7 million . Direct costs incurred by the VIEVU legal entity and costs attributable to legacy VIEVU employees were approximately $16.9 million through December 31, 2018. The following unaudited pro forma financial information presents the combined results of operations for the years ending December 31, 2018, and 2017, respectively, as though the VIEVU acquisition that occurred during the reporting period had occurred as of January 1, 2017. The unaudited pro forma results include certain adjustments, which are primarily comprised of the change in amortization of intangible assets established in purchase accounting compared to VIEVU's legacy intangible assets, and reclassifying the expense recorded during the three months ended June 30, 2018 related to assumed purchase commitments to the pro forma 2017 results. In addition, we have made pro forma adjustments in 2018 to exclude nonrecurring transaction costs directly attributable to the acquisition. These unaudited pro forma results of operations are presented for informational purposes only as required by U.S. GAAP, and do not include any anticipated cost savings or other effects of future integration efforts associated with the Company's acquisition strategy to secure major city customer relationships. As such, they may not be indicative of the results we would have achieved if the acquisition had taken place on January 1, 2017, nor are they indicative of future results of operations (in thousands, except per share amounts): For the Years Ended December 31, 2018 2017 Net sales $ 423,890 $ 352,985 Net income (loss) $ 27,035 $ (2,145 ) Net income (loss) per share: Basic $ 0.49 $ (0.04 ) Diluted $ 0.47 $ (0.04 ) In connection with the acquisition, we incurred and expensed costs of approximately $0.8 million , which included legal, accounting and other third-party expenses related to the transaction. Subsequent to the acquisition date, we recorded expenses of $1.2 million related to purchase commitments assumed in the VIEVU business combination that exceeded estimated future demand.

Segment Data

Segment Data	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Data	Segment Data Our operations are comprised of two reportable segments: the manufacture and sale of CEWs, batteries, accessories, extended warranties and other products and services (the “TASER” segment); and the development, manufacture, and sale of software and sensors, which includes the sale of devices, wearables, applications, cloud and mobile products (collectively, the “Software and Sensors” segment). Within the Software and Sensors segment, we specify sales of products and services. Revenue from our “products” in the Software and Sensors segment are generally from sales of sensors, including on-officer body cameras, Axon Fleet cameras, other hardware sensors, warranties on sensors,and other products, and is sometimes referred to as "Sensors and Other revenue." Revenue from our “services” in the Software and Sensors segment comprise sales related to the Axon Cloud, which includes Axon Evidence, cloud-based evidence management software revenue, other recurring cloud-hosted software revenue and related professional services, and is sometimes referred to as "Axon Cloud revenue." Within the Software and Sensors segment, we include only revenues and costs attributable to that segment which costs include: costs of sales for both products and services, direct labor, selling expenses for the sales team, product management and R&D for products included, or to be included, within the Software and Sensors segment. All other costs are included in the TASER segment. Our Chief Executive Officer, who is the CODM, is not provided asset information by segment, and therefore, no asset information is provided. Information relative to our reportable segments was as follows (in thousands): For the year ended December 31, 2018 TASER Software and Sensors Total Net sales from products $ 253,115 $ 74,520 $ 327,635 Net sales from services — 92,433 92,433 Net sales 253,115 166,953 420,068 Cost of product sales 80,354 58,983 139,337 Cost of service sales — 22,148 22,148 Cost of sales 80,354 81,131 161,485 Gross margin 172,761 85,822 258,583 Sales, general and administrative 90,910 65,976 156,886 Research and development 17,012 59,844 76,856 Income (loss) from operations $ 64,839 $ (39,998 ) $ 24,841 For the year ended December 31, 2017 TASER Software and Sensors Total Net sales from products (1) $ 234,512 $ 51,347 $ 285,859 Net sales from services (1) — 57,939 57,939 Net sales (1) 234,512 109,286 343,798 Cost of product sales 72,054 45,943 117,997 Cost of service sales — 18,713 18,713 Cost of sales 72,054 64,656 136,710 Gross margin 162,458 44,630 207,088 Sales, general and administrative (1) 78,202 60,490 138,692 Research and development 8,377 46,996 55,373 Income (loss) from operations $ 75,879 $ (62,856 ) $ 13,023 For the year ended December 31, 2016 TASER Software and Sensors Total Net sales from products (1) $ 202,644 $ 35,929 $ 238,573 Net sales from services (1) — 29,672 29,672 Net sales (1) 202,644 65,601 268,245 Cost of product sales 61,930 29,606 91,536 Cost of service sales — 6,173 6,173 Cost of sales 61,930 35,779 97,709 Gross margin 140,714 29,822 170,536 Sales, general and administrative (1) 63,617 44,459 108,076 Research and development 5,887 24,722 30,609 Income (loss) from operations $ 71,210 $ (39,359 ) $ 31,851 (1) Amounts for the years ended December 31, 2017 and 2016 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (unaudited)	Selected Quarterly Financial Data (unaudited) Selected quarterly financial data for years ended December 31, 2018 and 2017 follows (in thousands, except per share data): Quarter Ended March 31, June 30, September 30, December 31, 2018 2018 2018 2018 (1) Net sales $ 101,215 $ 99,226 $ 104,836 $ 114,791 Gross margin 64,461 63,143 65,633 65,346 Net income 12,926 8,485 5,711 2,083 Earnings per share (2) : Basic $ 0.24 $ 0.15 $ 0.10 $ 0.04 Diluted $ 0.24 $ 0.15 $ 0.10 $ 0.03 Quarter Ended March 31, June 30, September 30, December 31, 2017 2017 2017 2017 Net sales (3) $ 79,242 $ 79,643 $ 90,262 $ 94,651 Gross margin 48,670 45,637 49,765 63,016 Net income (loss) (3) 4,580 2,276 422 (2,071 ) Earnings (loss) per share (2) (3) : Basic $ 0.09 $ 0.04 $ 0.01 $ (0.04 ) Diluted $ 0.09 $ 0.04 $ 0.01 $ (0.04 ) (1) Results of operations for the three months ended December 31, 2018 included out of period adjustments related to prior quarterly periods in 2018 and 2017. The aggregate out of period adjustment was approximately $1.8 million , reflecting a $0.9 million decrease to net sales, a $1.3 million increase to sales, general and administrative expense, and a $0.4 million decrease to provision for income taxes. Based on our quantitative and qualitative analysis, we do not consider the out of period impact to be material to our financial position or results of operations for any prior periods or for the quarter or year ended December 31, 2018. (2) Basic and diluted earnings per share are computed independently for each of the quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted earnings per share. (3) Amounts for 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605.

Supplemental Disclosure to Cash

Supplemental Disclosure to Cash Flows	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure to Cash Flows	Supplemental Disclosure to Cash Flows Supplemental non-cash and other cash flow information were as follows as of and for the years ended December 31 (in thousands): 2018 2017 2016 Supplemental disclosures: Cash and cash equivalents $ 349,462 $ 75,105 $ 40,651 Restricted cash $ 1,565 $ 3,333 $ 3,317 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 351,027 $ 78,438 $ 43,968 Cash paid for income taxes, net of refunds $ 10,609 $ 11,487 $ 14,048 Non-cash transactions: Contingent consideration related to business combinations $ — $ 1,007 $ 3,325 Property and equipment purchases in accounts payable 501 133 82 Non-cash purchase consideration related to business combinations 12,508 — — Purchase of assets under capital lease obligations — — 134

Schedule II- Valuation and Qual

Schedule II- Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS (Dollars in thousands) Description Balance at Beginning of Period Charged to Costs and Expenses Charged to Other Accounts Deductions Balance at End of Period Allowance for doubtful accounts: Year ended December 31, 2018 $ 729 $ 1,189 $ — $ (36 ) $ 1,882 Year ended December 31, 2017 443 592 — (306 ) 729 Year ended December 31, 2016 322 205 — (84 ) 443

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The preparation of these consolidated financial statements 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 consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions in these consolidated financial statements include: • product warranty reserves, • inventory valuation, • revenue recognition, • valuation of goodwill, intangible and long-lived assets, • recognition, measurement and valuation of current and deferred income taxes, • stock-based compensation, • recognition and measurement of contingencies and accrued litigation expense, and • fair values of identified tangible and intangible assets acquired and liabilities assumed in business combinations. Actual results could differ materially from those estimates.
Cash, Cash Equivalents and Investments	Cash, Cash Equivalents and Investments Cash, cash equivalents and investments include cash, money market funds, certificates of deposit, state and municipal obligations and corporate bonds. We place our cash and cash equivalents with high quality financial institutions. Although we deposit our cash with multiple financial institutions, our deposits regularly exceed federally insured limits. Cash and cash equivalents include funds on hand and highly liquid investments purchased with initial maturity of three months or less. Short-term investments include securities with an expected maturity date within one year of the balance sheet date that do not meet the definition of a cash equivalent, and long-term investments are securities with an expected maturity date greater than one year. Based on management’s intent and ability, our investments are classified as held to maturity investments and are recorded at amortized cost. Held-to-maturity investments are reviewed quarterly for impairment to determine if other-than-temporary declines in the fair value have occurred for any individual investment that may affect our intent and ability to hold the investment until recovery. Other-than-temporary declines in the value of held-to-maturity investments are recorded as expense in the period the determination is made.
Inventory	Inventory Inventories are stated at the lower of cost and net realizable value. Cost is determined using the weighted average cost of raw materials, which approximates the first-in, first-out (“FIFO”) method and includes allocations of manufacturing labor and overhead. Provisions are made to reduce potentially excess, obsolete or slow-moving inventories, as well as trial and evaluation inventories to their net realizable value. These provisions are based on management’s best estimate after considering historical demand, projected future demand, inventory purchase commitments, industry and market trends and conditions among other factors. We evaluate inventory costs for abnormal costs due to excess production capacity and treat such costs as period costs.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation and amortization. Additions and improvements are capitalized, while ordinary maintenance and repair expenditures are charged to expense as incurred. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets.
Software Development Costs	Software Development Costs We expense software development costs, including costs to develop software products or the software component of products and services to be marketed to external users, before technological feasibility of such products is reached. We have determined that technological feasibility is reached shortly before the release of those products and as a result, the development costs incurred after the establishment of technological feasibility and before the release of those products are not material. Software development costs also include costs to develop software programs to be used solely to meet our internal needs and applications. We capitalize development costs related to these software applications once the preliminary project stage is complete and it is probable that the project will be completed and the software will be used to perform the intended function. Additionally, we capitalize qualifying costs incurred for upgrades and enhancements to existing software that result in additional functionality. Costs related to preliminary project planning activities, post-implementation activities, maintenance and minor modifications are expensed as incurred. Internal-use software is amortized on a straight line basis over its estimated useful life. We evaluate the useful lives of these assets on an annual basis and test for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets.
Valuation of Goodwill, Intangibles and Long-lived Assets	Valuation of Goodwill, Intangible and Long-lived Assets We do not amortize goodwill and intangible assets with indefinite useful lives; rather, such assets are required to be tested for impairment at least annually, or sooner whenever events or changes in circumstances indicate that the assets may be impaired. We perform our annual impairment assessment in the fourth quarter of each year. Finite-lived intangible assets and other long-lived assets are amortized over their estimated useful lives. Management evaluates whether events and circumstances have occurred that indicate the remaining estimated useful life of long-lived assets and intangible assets may warrant revision or that the remaining balance of these assets, including intangible assets with indefinite lives, may not be recoverable. Circumstances that might indicate long-lived assets might not be recoverable could include, but are not limited to, a change in the product mix, a change in the way products and services are created, produced or delivered, or a significant change in the way our products are branded and marketed. When performing a review for recoverability, management estimates the future undiscounted cash flows expected to result from the use of the assets and their eventual disposition. The amount of the impairment loss, if impairment exists, is calculated based on the excess of the carrying amounts of the assets over their estimated fair value computed using discounted cash flows.
Customer Deposits	Customer Deposits We require deposits in advance of shipment for certain customer sales orders. Additionally, customers may elect to make deposits with us related to contracts for our products and services that were not executed as of the end of a reporting period. Customer deposits are recorded as a current liability in the accompanying consolidated balance sheets.
Revenue Recognition, Deferred Revenue and Accounts and Notes Receivable	Revenue Recognition, Deferred Revenue and Accounts and Notes Receivable We derive revenue from two primary sources: (1) the sale of physical products, including CEWs, Axon cameras, Axon Signal enabled devices, corresponding hardware extended warranties, and related accessories such as Axon docks, cartridges and batteries, among others, and (2) subscriptions to our Axon Evidence digital evidence management software as a service ("SaaS") (including data storage fees and other ancillary services), which includes varying levels of support. To a lesser extent, we also recognize training, professional services and revenue related to other software and SaaS services. We apply the five-step model outlined in Accounting Standards Codification Topic 606, Revenue from Contracts from Customers ("Topic 606"). For additional discussion of the adoption of Topic 606, see Note 2. Many of our products and services are sold on a standalone basis. We also bundle our hardware products and services together and sell them to our customers in single transactions, where the customer can make payments over a multi-year period. These sales may include payments for upfront hardware and services, as well as payments for hardware and services to be provided by us at a future date. Additionally, we offer customers the ability to purchase CEW cartridges and certain services on an unlimited basis over the contractual term. Due to the unlimited nature of these arrangements whereby we are obligated to deliver unlimited products at the customer’s request, we account for these arrangements as stand-ready obligations, and recognize revenue ratably over the contract period. Cost of product sales is recognized as the products are shipped to the customer. Revenues are recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration we expect to receive in exchange for those products or services. We enter into contracts that can include various combinations of products and services, each of which is generally distinct and accounted for as a separate performance obligation. Revenue is recognized net of allowances for returns and any taxes collected from customers, which are subsequently remitted to governmental taxing authorities. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer, and is the unit of account in Topic 606. For contracts with multiple performance obligations, we allocate the contract transaction price to each performance obligation using our estimate of the standalone selling price ("SSP") of each distinct good or service in the contract. Performance obligations to deliver products, including CEWs, cameras and related accessories such as cartridges, batteries and docks, are generally satisfied at the point in time we ship the product, as this is when the customer obtains control of the asset under our standard terms and conditions. In certain contracts with non-standard terms and conditions, these performance obligations may not be satisfied until formal customer acceptance occurs. Performance obligations to fulfill service-type extended warranties and provide our SaaS offerings, including Axon Evidence and other cloud services, are generally satisfied over time as the customer receives and consumes the benefits of these services over the stated service period. We have elected to recognize shipping costs as an expense in cost of product sales when the control of hardware products or accessories have transferred to the customer. Sales tax collected on sales is netted against government remittances and thus, recorded on a net basis. Deferred revenue consists of payments received and amounts invoiced in advance related to products and services for which the criteria for revenue recognition have not yet been met. Deferred revenue that will be recognized during the subsequent twelve month period from the balance sheet date is recorded as current deferred revenue and the remaining portion is recorded as long-term. Generally, customers are billed in annual installments. See Note 2 for further disclosures about our deferred revenue. Sales are typically made on credit, and we generally do not require collateral. Management performs ongoing credit evaluations of its customers’ financial condition, and maintains an allowance for doubtful accounts. Uncollectible accounts are charged to expense when deemed uncollectible, and accounts and notes receivable are presented net of an allowance for doubtful accounts. This allowance represents management’s best estimate and application of judgment considering a number of factors, including third-party credit reports, actual payment history, cash discounts, customer-specific financial information and broader market and economic trends and conditions. In the event that actual uncollectible amounts differ from our estimates, additional expense could be necessary. Cost of Product and Service Sales Cost of product sales represents manufacturing costs, consisting of materials, labor and overhead related to finished goods and components. Shipping costs incurred related to product delivery are also included in cost of products sold. Cost of service sales includes third-party cloud services, and software maintenance and support costs, including personnel costs, associated with supporting Evidence.com and other software related services.
Advertising Costs	Advertising Costs We expense advertising costs in the period in which they are incurred. We incurred advertising costs of $1.1 million , $0.5 million and $0.4 million in the years ended December 31, 2018 , 2017 and 2016 , respectively. Advertising costs are included in sales, general and administrative expenses in the accompanying statements of operations.
Standard Warranties	Standard Warranties We warranty our CEWs, Axon cameras and certain related accessories from manufacturing defects on a limited basis for a period of one year after purchase and, thereafter, will replace any defective unit for a fee. Estimated costs for the standard warranty are charged to cost of products sold when revenue is recorded for the related product. Future warranty costs are estimated based on historical data related to warranty claims on a quarterly basis and this rate is applied to current product sales. Historically, reserve amounts have been increased if management becomes aware of a component failure or other issue that could result in larger than anticipated warranty claims from customers. The warranty reserve is reviewed quarterly to verify that it sufficiently reflects the remaining warranty obligations based on the anticipated expenditures over the balance of the warranty obligation period, and adjustments are made when actual warranty claim experience differs from estimates. The warranty reserve is included in accrued liabilities on the accompanying consolidated balance sheets.
Research and Development Expenses	Research and Development Expenses We expense as incurred research and development costs that do not meet the qualifications to be capitalized.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement amounts of assets and liabilities and their respective tax bases and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in future years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rate is recognized in income in the period that includes the enactment date. Deferred tax assets are reduced through the establishment of a valuation allowance if, based upon available evidence, it is determined that it is more likely than not that the deferred tax assets will not be realized. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate resolution. Management also assesses whether uncertain tax positions, as filed, could result in the recognition of a liability for possible interest and penalties. Our policy is to include interest and penalties related to unrecognized tax benefits as a component of income tax expense.
Concentration of Credit Risk and Major Customers / Suppliers	Concentration of Credit Risk and Major Customers / Suppliers Financial instruments that potentially subject us to concentrations of credit risk consist of accounts and notes receivable, contract assets, and cash. Sales are typically made on credit and we generally do not require collateral. Management performs ongoing credit evaluations of its customers’ financial condition and maintains an allowance for estimated losses. Uncollectible accounts are written off when deemed uncollectible, and accounts receivable are presented net of an allowance for doubtful accounts, which totaled $1.9 million and $0.8 million as of December 31, 2018 and 2017 , respectively. Historically, we have experienced a low level of write-offs related to uncollectible accounts. We maintain the majority of our cash at four depository institutions. As of December 31, 2018 , the aggregate balances in such accounts were $342.3 million . Our balances with these institutions regularly exceed Federal Deposit Insurance Corporation (“FDIC”) insured limits for domestic deposits and various deposit insurance programs covering our deposits in Australia, Germany, Finland, the Netherlands, the United Kingdom, and Vietnam. To manage the related credit exposure, management continually monitors the creditworthiness of the financial institutions where we have deposits. We sell some of our products through a network of unaffiliated distributors. We also sell directly to customers. No customer represented more than 10% of total net sales for the years ended December 31, 2018 , 2017 or 2016 . At December 31, 2018 , and 2017, no customer represented more than 10% of the aggregate balance of accounts and notes receivable and contract assets. We currently purchase finished circuit boards and injection-molded plastic components from suppliers located in the U.S., Mexico and Taiwan. Although we currently obtain many of these components from single source suppliers, we own the injection molded component tooling used in their production. As a result, management believes it could obtain alternative suppliers in most cases without incurring significant production delays. We also purchase small, machined parts from a vendor in Taiwan, custom cartridge components from a proprietary vendor in the U.S., and electronic components from a variety of international and domestic distributors. We believe that there are readily available alternative suppliers in most cases who could consistently meet our needs for these components. We acquire most of our components on a purchase order basis and do not have any significant long-term contracts with suppliers.
Fair Value of Financial Instruments	Fair Value of Financial Instruments We use the fair value framework that prioritizes the inputs to valuation techniques for measuring financial assets and liabilities measured on a recurring basis and for non-financial assets and liabilities when these items are re-measured. Fair value is considered to be the exchange price in an orderly transaction between market participants, to sell an asset or transfer a liability at the measurement date. The hierarchy below lists three levels of fair value based on the extent to which inputs used in measuring fair value are observable in the market. We categorize each of our fair value measurements in one of these three levels based on the lowest level input that is significant to the fair value measurement in its entirety. These levels are: • Level 1 – Valuation techniques in which all significant inputs are unadjusted quoted prices from active markets for assets or liabilities that are identical to the assets or liabilities being measured. • Level 2 – Valuation techniques in which significant inputs include quoted prices from active markets for assets or liabilities that are similar to the assets or liabilities being measured and/or quoted prices for assets or liabilities that are identical or similar to the assets or liabilities being measured from markets that are not active. Also, model-derived valuations in which all significant inputs and significant value drivers are observable in active markets are Level 2 valuation techniques. • Level 3 – Valuation techniques in which one or more significant inputs or significant value drivers are unobservable. Unobservable inputs are valuation technique inputs that reflect our own assumptions about inputs that market participants would use in pricing an asset or liability. We have cash equivalents and investments, which at December 31, 2018 and 2017 , were comprised of money market funds, state and municipal obligations, corporate bonds, and certificates of deposits. See additional disclosure regarding the fair value of our cash equivalents and investments in Note 3. Included in the balance of other assets as of December 31, 2018 and 2017 was $3.6 million and $3.8 million , respectively, related to corporate-owned life insurance policies which are used to fund our deferred compensation plan. We determine the fair value of our insurance contracts by obtaining the cash surrender value of the contracts from the issuer, a Level 2 valuation technique. Our financial instruments also include accounts and notes receivable, accounts payable and accrued liabilities. Due to the short-term nature of these instruments, their fair values approximate their carrying values on the balance sheet.
Segment and Geographic Information	Segment and Geographic Information Our operations are comprised of two reportable segments: the manufacture and sale of CEWs, batteries, accessories, extended warranties and other products and services (the “TASER” segment); and the development, manufacture and sale of software and sensors, which includes the sale of devices, wearables, applications, cloud and mobile products (collectively, the "Software and Sensors" segment). Reportable segments are determined based on discrete financial information reviewed by our Chief Executive Officer who is our chief operating decision maker ("CODM"). We organize and review operations based on products and services, and currently there are no operating segments that are aggregated. We perform an analysis of our reportable segments at least annually. Additional information related to our business segments is summarized in Note 16.
Sales to Customers Outside of the U.S.	Sales to customers outside of the U.S. are typically denominated in U.S. dollars and are attributed to each country based on the shipping address of the distributor or customer.
Stock-Based Compensation	Stock-Based Compensation We recognize expense related to stock-based compensation transactions in which we receive services in exchange for equity instruments of the Company. Stock-based compensation expense for RSUs is measured based on the closing fair market value of our common stock on the date of grant. We recognize stock-based compensation expense over the award’s requisite service period on a straight-line basis for time-based RSUs and on a graded basis for RSUs that are contingent on the achievement of performance conditions. We recognize forfeitures as they occur as a reduction to stock-based compensation expense and to additional paid-in-capital. Historically, we have calculated the fair value of stock options using the Black-Scholes-Merton option pricing valuation model, which incorporates various assumptions including expected volatility, expected life, expected dividends and risk-free interest rates.
Income per Common Share	Income per Common Share Basic income per common share is computed by dividing net income by the weighted average number of common shares outstanding during the periods presented. Diluted income per share reflects the potential dilution from outstanding stock options and unvested restricted stock units.
Recently Issued Accounting Guidance	Recently Issued Accounting Guidance Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”) and Accounting Standards Codification ("ASC") Subtopic 340-40, Other Assets and Deferred Costs - Contracts with Customers ("ASC 340-40"), (collectively, “Topic 606”). On January 1, 2018, we adopted Topic 606 by applying the modified retrospective method of adoption for all contracts that were not substantially completed as of the adoption date. ASU 2014-09 requires entities to recognize revenue through the application of a five-step model, which includes identification of the contract, identification of the performance obligations, determination of the transaction price, allocation of the transaction price to the performance obligations and recognition of revenue as the entity satisfies the performance obligations. Refer to Note 2 for further discussion. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 eliminates the diversity in practice related to the classification of certain cash receipts and payments. ASU 2016-15 designates the appropriate cash flow classification, including requirements to allocate certain components of these cash receipts and payments among operating, investing and financing activities. We adopted ASU 2016-15 effective January 1, 2018, and the adoption of this ASU did not have a material impact on our consolidated financial statements. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740) - Intra-Entity Transfers of Assets Other Than Inventory. ASU 2016-16 requires an entity to recognize income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. This removes the exception to postpone recognition until the asset has been sold to an outside party. We adopted ASU 2016-16 effective January 1, 2018, and the adoption of this ASU did not have a material impact on our consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows - Restricted Cash (Topic 230), which amends the existing guidance relating to the treatment of restricted cash and restricted cash equivalents on the statement of cash flows. We adopted ASU 2016-18 effective January 1, 2018, and retrospectively updated the presentation of our consolidated statements of cash flows to include amounts of restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805) to provide a more robust framework to use in determining when a set of acquired assets and activities is a business. The amendments in ASU 2017-01 provide a screen to determine when a set of acquired integrated assets and activities is not a business, and if the screen is not met it may result in fewer transactions that qualify as a business combination under ASC Topic 805. We adopted ASU 2017-01 effective January 1, 2018, and the adoption of this ASU did not have a material impact on our consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718), which provides guidance on determining which changes to the terms and conditions of share-based payment awards require an entity to apply modification accounting under Topic 718. We adopted ASU 2017-09 effective January 1, 2018, and the adoption of this ASU did not have a material impact on our consolidated financial statements. In September 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The guidance reduces complexity for the accounting for costs of implementing a cloud computing service arrangement and aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by the amendments. We adopted ASU 2018-15 prospectively effective July 1, 2018, and the adoption of this ASU did not have a material impact on our consolidated financial statements. Effective the first quarter of 2019: In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which is intended to increase transparency and comparability among organizations by requiring the recognition of right-of-use (“ROU”) assets and lease liabilities on the balance sheet. In July 2018, the FASB issued additional guidance which provided an additional transition method for adopting the updated guidance. Under the additional transition method, entities may elect to recognize a cumulative-effect adjustment to the opening balance of retained earnings in the year of adoption. We currently plan to adopt this standard using the modified retrospective approach. Most prominent among the changes in the standard is the requirement for lessees to recognize ROU assets and lease liabilities for those leases classified as operating leases under current U.S. GAAP. The standard requires additional disclosures to enable users of financial statements to assess the amount, timing, and certainty of cash flows arising from leases. We intend to elect certain of the available practical expedients upon adoption. We have evaluated our existing lease portfolio and believe that our population of leases is relatively low in number. We have implemented key processes and controls to enable the accurate assessment of leases and preparation of related financial information. We are nearing completion of the opening balance sheet adjustment related to ASU 2016-02. We expect adoption of the standard will result in the recognition of ROU assets of approximately $11 million and lease liabilities of approximately $12 million for operating leases as of January 1, 2019, with no impact to retained earnings. Additionally, we anticipate that our accounting for capital leases will remain substantially unchanged. In June 2018, the FASB issued ASU 2018-07, Compensation - Stock Compensation (Topic 718), expanding the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The adoption of this ASU is not expected to have a material impact on our consolidated financial statements. Effective the first quarter of 2020: In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 includes an impairment model (known as the current expected credit loss model) that is based on expected losses rather than incurred losses. Under the new guidance, an entity recognizes as an allowance its estimate of expected credit losses, which the FASB believes will result in more timely recognition of such losses. The use of forecasted information is intended to incorporate more timely information in the estimate of expected credit loss. Early adoption is permitted.We are currently in the process of evaluating the impact of adoption of ASU 2016-13 on our consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 eliminates, adds and modifies certain disclosure requirements for fair value measurements. The amendments applicable to the disclosures of changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted, and an entity is also permitted to early adopt any removed or modified disclosures and delay adoption of the additional disclosures until their effective date. As ASU 2018-13 only revises disclosure requirements, it will not have a material impact on our consolidated financial statements.
Reclassification of Prior Year Presentation	Reclassification of Prior Year Presentation Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported results of operations.

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	Additional assumptions used for the CEO Performance Award and the resulting estimates of weighted-average fair value per share of options granted are as follows: Volatility 47.71% Risk-free interest rate 2.98% Dividend rate — Expected life of options 9.76 years Weighted average grant date fair value of options granted $38.64
Summary of Changes in Estimated Product Warranty Liabilities	Changes in our estimated warranty reserve were as follows (in thousands): 2018 2017 2016 Balance, January 1 $ 644 $ 780 $ 314 Utilization of reserve (458 ) (245 ) (155 ) Warranty expense 712 109 621 Balance, December 31 $ 898 $ 644 $ 780
Net Sales by Geographic Area	For the years ended December 31, 2018 , 2017 and 2016 , net sales by geographic area as well as the percentage relationship to total net sales included in the accompanying statements of operations were as follows (in thousands): Year Ended December 31, 2018 2017 (1) 2016 (1) United States $ 335,310 79.8 % $ 282,810 82.3 % $ 218,757 81.6 % Other Countries 84,758 20.2 60,988 17.7 49,488 18.4 Total $ 420,068 100.0 % $ 343,798 100.0 % $ 268,245 100.0 % (1) Amounts for the years ended December 31, 2017 and 2016 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605.
Weighted Average Number of Shares Outstanding and Income Per Share	The calculation of the weighted average number of shares outstanding and earnings per share are as follows (in thousands except per share data): For the Year Ended December 31, 2018 2017 2016 Numerator for basic and diluted earnings per share: Net income $ 29,205 $ 5,207 $ 17,297 Denominator: Weighted average shares outstanding—basic 56,392 52,726 52,667 Dilutive effect of stock-based awards 1,530 1,172 869 Diluted weighted average shares outstanding 57,922 53,898 53,536 Anti-dilutive stock-based awards excluded 6,757 386 443 Net income per common share: Basic $ 0.52 $ 0.10 $ 0.33 Diluted $ 0.50 $ 0.10 $ 0.32

Revenues (Tables)

Revenues (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The impacts to the December 31, 2017 balance sheet of adopting Topic 606 are presented below (in thousands): December 31, 2017 (As reported) Impact of Adoption of Topic 606 on Opening Balance Sheet January 1, 2018 (As adjusted) Accounts and notes receivable, net $ 56,064 $ 28,915 $ 84,979 Contract assets, net — 5,512 5,512 Prepaid expense and other current assets 21,696 2,003 23,699 Total impacted current assets 77,760 36,430 114,190 Deferred income tax assets, net 15,755 (5,158 ) 10,597 Long-term notes receivable 36,877 (12,977 ) 23,900 Other assets 15,366 5,323 20,689 Total impacted assets 145,758 23,618 169,376 Accrued liabilities 23,502 2,512 26,014 Current portion of deferred revenue 70,401 863 71,264 Total impacted current liabilities 93,903 3,375 97,278 Deferred revenue, net of current portion 54,881 1,249 56,130 Total impacted liabilities 148,784 4,624 153,408 Retained earnings 123,185 18,994 142,179 Total impacted stockholders' equity 123,185 18,994 142,179 Total impacted liabilities and stockholders' equity 271,969 23,618 295,587 The following table presents our revenues by primary product and service offering (in thousands): Year Ended December 31, 2018 Year Ended December 31, 2017 (1) TASER Software and Sensors Total TASER Software and Sensors Total TASER 7 $ 7,358 $ — $ 7,358 $ — $ — $ — TASER X26P 70,638 — 70,638 64,426 — 64,426 TASER X2 78,837 — 78,837 81,417 — 81,417 TASER Pulse and Bolt 5,182 — 5,182 4,340 — 4,340 Cartridges 68,258 — 68,258 63,203 — 63,203 Axon Body — 21,883 21,883 — 15,184 15,184 Axon Flex — 6,509 6,509 — 10,083 10,083 Axon Fleet — 12,527 12,527 — 2,954 2,954 Axon Dock — 10,706 10,706 — 9,736 9,736 Axon Evidence and cloud services — 90,291 90,291 — 57,841 57,841 TASER Cam — 3,871 3,871 — 3,358 3,358 Extended warranties 15,753 11,860 27,613 12,426 7,110 19,536 Other 7,089 9,306 16,395 8,700 3,020 11,720 Total $ 253,115 $ 166,953 $ 420,068 $ 234,512 $ 109,286 $ 343,798 (1) Amounts for the year ended December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605.
Summary of Deferred Revenue	The following table presents our contract assets, contract liabilities and certain information related to these balances as of and for the year ended December 31, 2018 (in thousands): December 31, 2018 Contract assets, net $ 13,960 Contract liabilities (deferred revenue) 181,433 Revenue recognized in the period from: Amounts included in contract liabilities at the beginning of the period 63,475 Contract liabilities (deferred revenue) consisted of the following (in thousands): December 31, 2018 December 31, 2017 (1) Current Long-Term Total Current Long-Term Total Warranty: TASER $ 12,797 $ 16,847 $ 29,644 $ 12,501 $ 18,619 $ 31,120 Software and Sensors 8,273 6,516 14,789 6,293 4,195 10,488 21,070 23,363 44,433 18,794 22,814 41,608 Hardware: TASER 9,355 15,598 24,953 4,164 11,401 15,565 Software and Sensors 20,878 24,685 45,563 16,956 14,781 31,737 30,233 40,283 70,516 21,120 26,182 47,302 Software and Sensors Services 55,713 10,771 66,484 30,487 5,885 36,372 Total $ 107,016 $ 74,417 $ 181,433 $ 70,401 $ 54,881 $ 125,282 December 31, 2018 December 31, 2017 (1) Current Long-Term Total Current Long-Term Total TASER $ 22,152 $ 32,445 $ 54,597 $ 16,665 $ 30,020 $ 46,685 Software and Sensors 84,864 41,972 126,836 53,736 24,861 78,597 Total $ 107,016 $ 74,417 $ 181,433 $ 70,401 $ 54,881 $ 125,282 (1) Amounts as of December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605. December 31, 2018 December 31, 2017 (1) Current Long-Term Total Current Long-Term Total Warranty: TASER $ 12,797 $ 16,847 $ 29,644 $ 12,501 $ 18,619 $ 31,120 Software and Sensors 8,273 6,516 14,789 6,293 4,195 10,488 21,070 23,363 44,433 18,794 22,814 41,608 Hardware: TASER 9,355 15,598 24,953 4,164 11,401 15,565 Software and Sensors 20,878 24,685 45,563 16,956 14,781 31,737 30,233 40,283 70,516 21,120 26,182 47,302 Software and Sensors Services 55,713 10,771 66,484 30,487 5,885 36,372 Total $ 107,016 $ 74,417 $ 181,433 $ 70,401 $ 54,881 $ 125,282 December 31, 2018 December 31, 2017 (1) Current Long-Term Total Current Long-Term Total TASER $ 22,152 $ 32,445 $ 54,597 $ 16,665 $ 30,020 $ 46,685 Software and Sensors 84,864 41,972 126,836 53,736 24,861 78,597 Total $ 107,016 $ 74,417 $ 181,433 $ 70,401 $ 54,881 $ 125,282 (1) Amounts as of December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605. Remaining Performance Obligations As of December 31, 2018 , we had approximately $900 million of remaining performance obligations, which included both recognized contract liabilities as well as amounts that will be invoiced and recognized in future periods. The remaining performance obligations are limited only to arrangements that meet the definition of a contract under Topic 606 as of December 31, 2018 . We expect to recognize between 15% - 20% of this balance over the next twelve months, and expect the remainder to be recognized over the following five to seven years, subject to risks related to delayed deployments, budget appropriation or other contract cancellation clauses. Costs to Obtain a Contract We recognize an asset for the incremental costs of obtaining a contract with a customer, which consist primarily of sales commissions. These costs are ascribed to or allocated to the underlying performance obligations in the contract and amortized consistent with the recognition timing of the revenue for the underlying performance obligations. For contract costs related to performance obligations with an amortization period of one year or less, we apply the practical expedient to expense these sales commissions when incurred. These costs are recognized as incurred within sales, general and administrative expenses on the accompanying consolidated statements of operations and comprehensive income. As of December 31, 2018 , our assets for costs to obtain contracts were as follows (in thousands): December 31, 2018 Current deferred commissions (1) $ 7,062 Deferred commissions, net of current portion (2) 15,530 $ 22,592 (1) Current deferred commissions are included within prepaid expenses and other current assets on the accompanying consolidated balance sheet. (2) Deferred commissions, net of current portion, are included in other assets on the accompanying consolidated balance sheet. During the year ended December 31, 2018 , we recognized $5.3 million of amortization related to deferred commissions. These costs are recorded within sales, general and administrative expenses on the accompanying consolidated statements of operations and comprehensive income. Significant Judgments Our contracts with certain municipal government customers may be subject to budget appropriation, other contract cancellation clauses or future periods which are optional. In contracts where the customer’s performance is subject to budget appropriation clauses, we generally consider the likelihood of non-appropriation to be remote when determining the contract term and transaction price. Contracts with other cancellation provisions or optional periods may require judgment in determining the contract term, including the existence of material rights, transaction price and identifying the performance obligations. At times, customers may request changes that either amend, replace or cancel existing contracts. Judgment is required to determine whether the specific facts and circumstances within the contracts require the changes to be accounted for as a separate contract or as a modification. Generally, contract modifications containing additional goods and services that are determined to be distinct and sold at their SSP are accounted for as a separate contract. For contract modifications where both criteria are not met, the original contract is updated and the required adjustments to revenue and contract assets, liabilities, and other accounts will be made accordingly. Our contracts with customers often include promises to transfer multiple products and services to a customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately rather than together may require significant judgment. We consider CEW devices and related accessories, as well as cameras and related accessories, to be separately identifiable from each other as well as from extended warranties on these products and the SaaS subscriptions to Axon Evidence and other cloud services. In contracts where there are timing differences between when we transfer a promised good or service to the customer and when the customer pays for that good or service, we have determined that, with the exception of our TASER 60 installment purchase arrangements, our contracts generally do not include a significant financing component. For the year ended December 31, 2018 , we recorded revenue of $48.2 million , including $1.3 million of interest income, under our TASER 60 plan. For the year ended December 31, 2017, we recorded revenue of $40.7 million including $0.7 million of interest income under our TASER 60 plan. Amounts for the year ended December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606. Judgment is required to determine the SSP for each distinct performance obligation.We analyze separate sales of our products and services as a basis for estimating the SSP of our products and services and then use that SSP as the basis for allocating the transaction price when our products and services are sold together in a contract with multiple performance obligations. In instances where the SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include market conditions, time value of money and other observable inputs. We typically have more than one SSP for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, we may use information such as geographic region and distribution channel in determining the SSP.
Capitalized Contract Cost	As of December 31, 2018 , our assets for costs to obtain contracts were as follows (in thousands): December 31, 2018 Current deferred commissions (1) $ 7,062 Deferred commissions, net of current portion (2) 15,530 $ 22,592 (1) Current deferred commissions are included within prepaid expenses and other current assets on the accompanying consolidated balance sheet. (2) Deferred commissions, net of current portion, are included in other assets on the accompanying consolidated balance sheet.

Cash, Cash Equivalents and In_2

Cash, Cash Equivalents and Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Summary of Cash, Cash Equivalents and Held-to-Maturity Investments by Type	The following tables summarize the Company's cash, cash equivalents, and held-to-maturity investments at December 31, 2018 and December 31, 2017 (in thousands): As of December 31, 2018 Amortized Cost Gross Unrealized Losses Fair Value Cash and Cash Equivalents Short-Term Investments Cash $ 144,095 $ — $ 144,095 $ 144,095 $ — Level 1: Money market funds 205,367 — 205,367 205,367 — Total $ 349,462 $ — $ 349,462 $ 349,462 $ — As of December 31, 2017 Amortized Cost Gross Unrealized Losses Fair Value Cash and Cash Equivalents Short-Term Investments Cash $ 53,459 $ — $ 53,459 $ 53,459 $ — Level 1: Money market funds 20,884 — 20,884 20,884 — Corporate bonds 6,632 (6 ) 6,626 — 6,632 Subtotal 27,516 (6 ) 27,510 20,884 6,632 Level 2: State and municipal obligations 992 — 992 762 230 Subtotal 992 — 992 762 230 Total $ 81,967 $ (6 ) $ 81,961 $ 75,105 $ 6,862

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventory	Provisions are made to reduce excess, obsolete or slow-moving inventories to their net realizable value. Inventories consisted of the following at December 31 (in thousands): 2018 2017 Raw materials $ 19,670 $ 20,119 Finished goods 14,093 25,346 Total inventory $ 33,763 $ 45,465

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consisted of the following at December 31 (in thousands): Estimated Useful Life 2018 2017 Land N/A $ 2,900 $ 2,900 Building and leasehold improvements 3-39 years 19,578 18,383 Production equipment 3-7 years 19,817 19,075 Computers, equipment and software 3-5 years 8,392 6,780 Furniture and office equipment 5-7 years 6,529 5,262 Vehicles 5 years 1,385 1,057 Website development costs 3 years 687 687 Capitalized internal-use software development costs 3 years 3,670 3,695 Construction-in-process N/A 14,820 9,810 Total cost 77,778 67,649 Less: Accumulated depreciation (39,885 ) (36,477 ) Property and equipment, net $ 37,893 $ 31,172

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amount of goodwill for the year ended December 31, 2018 were as follows (in thousands): TASER Software and Sensors Total Balance, January 1, 2018 $ 1,453 $ 13,474 $ 14,927 Goodwill acquired — 10,285 10,285 Foreign currency translation adjustments (115 ) (116 ) (231 ) Balance, December 31, 2018 $ 1,338 $ 23,643 $ 24,981
Intangible Assets Other than goodwill	Intangible assets (other than goodwill) consisted of the following (in thousands): December 31, 2018 December 31, 2017 Useful Life Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Amortizable (definite-lived) intangible assets: Domain names 5-10 years $ 3,161 $ (732 ) $ 2,429 $ 3,161 $ (428 ) $ 2,733 Issued patents 4-15 years 2,940 (1,106 ) 1,834 2,697 (913 ) 1,784 Issued trademarks 3-11 years 1,053 (599 ) 454 860 (397 ) 463 Customer relationships 4-8 years 3,701 (880 ) 2,821 1,377 (451 ) 926 Non-compete agreements 3-4 years 540 (439 ) 101 556 (346 ) 210 Developed technology 3-7 years 13,404 (7,081 ) 6,323 13,469 (3,956 ) 9,513 Re-acquired distribution rights 2 years 1,928 (1,813 ) 115 2,133 (711 ) 1,422 Total amortizable 26,727 (12,650 ) 14,077 24,253 (7,202 ) 17,051 Non-amortizable (indefinite-lived) intangible assets: TASER trademark 900 900 900 900 Patents and trademarks pending 958 958 872 872 Total non-amortizable 1,858 1,858 1,772 1,772 Total intangible assets $ 28,585 $ (12,650 ) $ 15,935 $ 26,025 $ (7,202 ) $ 18,823
Estimated Amortization Expense of Intangible Assets	Estimated amortization for intangible assets with definitive lives for the next five years ended December 31, and thereafter, is as follows (in thousands): 2019 $ 3,463 2020 3,294 2021 2,852 2022 1,211 2023 934 Thereafter 2,323 Total $ 14,077

Other Long-Term Assets (Tables)

Other Long-Term Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Long-Term Assets	Other long-term assets consisted of the following at December 31 (in thousands): 2018 2017 Cash surrender value of corporate-owned life insurance policies $ 3,596 $ 3,846 Deferred commissions (1) 15,530 6,803 Restricted cash (2) 661 3,333 Prepaid expenses, deposits and other 3,212 1,384 Total other long-term assets $ 22,999 $ 15,366 (1) Represents assets for the incremental costs of obtaining contracts with customers, which consist primarily of sales commissions. These costs are ascribed to or allocated to the underlying performance obligations in the contracts and amortized consistent with the recognition timing of the revenue for the underlying performance obligations. The amounts as of December 31, 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts. In connection with our adoption of Topic 606, we recorded an adjustment of $7.3 million as of January 1, 2018, and of that amount, $5.4 million was recorded within other assets. The adjusted balance of long-term deferred commissions as of January 1, 2018 was $12.2 million . (2) As of December 31, 2018, restricted cash primarily consisted of $0.6 million for a performance guarantee related to an international customer sales contract.

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued liabilities consisted of the following at December 31 (in thousands): 2018 2017 Accrued salaries, benefits and bonus $ 19,063 $ 8,957 Accrued professional, consulting and lobbying fees 4,894 3,870 Accrued warranty expense 898 644 Accrued income and other taxes 4,167 2,558 Other accrued expenses 12,070 7,473 Accrued liabilities $ 41,092 $ 23,502

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Lease Payments Under Non-Cancelable Leases	Future minimum lease payments under non-cancelable leases at December 31, 2018 , are as follows (in thousands): Operating Capital 2019 $ 3,670 $ 40 2020 3,572 36 2021 2,961 — 2022 2,001 — 2023 573 — Thereafter — — Total minimum lease payments $ 12,777 76 Less: Amount representing interest (6 ) Capital lease obligation $ 70

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	Income before income taxes included the following components for the years ended December 31 (in thousands): 2018 2017 2016 United States $ 25,751 $ 14,978 $ 38,414 Foreign 2,353 783 (6,917 ) Total $ 28,104 $ 15,761 $ 31,497
Significant Components of the Provision for Income Taxes	Significant components of the provision for income taxes are as follows for the years ended December 31 (in thousands): 2018 2017 2016 Current: Federal $ 4,900 $ 6,039 $ 16,346 State 1,377 1,263 1,534 Foreign 228 656 1,050 Total current 6,505 7,958 18,930 Deferred: Federal (8,382 ) 4,539 (4,145 ) State (364 ) (1,631 ) (977 ) Foreign (3 ) (78 ) (45 ) Total deferred (8,749 ) 2,830 (5,167 ) Tax impact of unrecorded tax benefits liability 1,143 (234 ) 437 Provision for income taxes (Income tax benefit) $ (1,101 ) $ 10,554 $ 14,200
Reconciliation of the Company's Effective Income Tax Rate to the Federal Statutory Rate	A reconciliation of our effective income tax rate to the federal statutory rate follows for the years ended December 31 (in thousands): 2018 2017 2016 Federal income tax at the statutory rate $ 5,902 $ 5,518 $ 11,024 State income taxes, net of federal benefit (215 ) 339 889 Difference between statutory and foreign tax rates 7 (560 ) 1,521 Permanent differences (1) 725 300 (457 ) Executive compensation limitation 1,167 — — Research and development (6,908 ) (2,380 ) (1,928 ) Return to provision adjustment 1,780 23 327 Change in liability for unrecognized tax benefits 1,768 7 700 Excess stock-based compensation benefit (2) (8,907 ) (1,819 ) (77 ) Change in valuation allowance 1,984 1,949 1,779 Tax effects of intercompany transactions 1,004 (277 ) 630 Adjustments to deferred tax assets, net resulting from enactment of new tax law (3) — 7,601 — Other 592 (147 ) (208 ) Provision for income taxes (Income tax benefit) $ (1,101 ) $ 10,554 $ 14,200 Effective tax rate (3.9 )% 66.9 % 45.1 % (1) Permanent differences include certain expenses that are not deductible for tax purposes including meals and entertainment, certain transaction costs, lobbying fees, and unfavorable income as a result of GILTI offset by favorable items including the domestic production activities deduction, for tax years 2017 and 2016, and a deduction for FDII for 2018. (2) For the years ended December 31, 2018 and 2017 , the provision for income taxes included $8.9 million and $1.8 million , respectively, of benefits resulting from excess stock-based compensation that were recorded as a decrease in the provision for income taxes. For the year ended December 31, 2016, we included $1.4 million of benefits resulting from excess stock-based compensation that were recorded as increases to additional paid-in capital in the consolidated statement of changes in stockholders' equity. (3) The adjustment to deferred tax assets of $7.6 million was a result of the impact of changes in the U.S. federal effective tax rate, as well as a reduction of the stock-based compensation deferred tax asset due to expected permanent limitations on its deductibility for certain key executives under the Tax Act.
Components of Deferred Income Tax Assets and Liabilities	Significant components of our deferred income tax assets and liabilities are as follows at December 31 (in thousands): 2018 2017 Deferred income tax assets: Net operating loss carryforward $ 2,347 $ 3,691 Deferred revenue 13,304 9,442 Deferred compensation 858 1,109 Inventory reserve 1,294 702 Non-qualified and non-employee stock option expense 3,758 3,704 Capitalized research and development — 485 Amortization 412 — Research and development tax credit carryforward 5,193 3,817 Reserves, accruals, and other 3,094 1,921 Total deferred income tax assets 30,260 24,871 Deferred income tax liabilities: Depreciation (2,195 ) (2,027 ) Amortization (57 ) (1,398 ) Other (1,232 ) (256 ) Total deferred income tax liabilities (3,484 ) (3,681 ) Net deferred income tax assets before valuation allowance 26,776 21,190 Valuation allowance (7,429 ) (5,435 ) Net deferred income tax assets $ 19,347 $ 15,755
Roll Forward of Liability for Unrecognized Tax Benefits Exclusive of Accrued Interest	The following table presents a roll forward of our liability for unrecognized tax benefits, exclusive of accrued interest, as of December 31 (in thousands): 2018 2017 2016 Balance, beginning of period $ 4,243 $ 4,050 $ 3,396 Increase in previous year tax positions 213 379 206 Increase in current year tax positions 1,982 587 448 Decrease due to lapse of statutes of limitations (380 ) (773 ) — Balance, end of period $ 6,058 $ 4,243 $ 4,050

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Equity Compensation Goals	Eight Separate Revenue Goals (1) (in thousands) Eight Separate Adjusted EBITDA (CEO Performance Award) Goals (in thousands) Goal #1, $710,058 Goal #9, $125,000 Goal #2, $860,058 Goal #10, $155,000 Goal #3, $1,010,058 Goal #11, $175,000 Goal #4, $1,210,058 Goal #12, $190,000 Goal #5, $1,410,058 Goal #13, $200,000 Goal #6, $1,610,058 Goal #14, $210,000 Goal #7, $1,810,058 Goal #15, $220,000 Goal #8, $2,010,058 Goal #16, $230,000 (1) In connection with the business acquisition that was completed during the three months ended June 30, 2018 (Note 15), the revenue goals have been adjusted for the acquiree's Target Revenue, as defined in the CEO Performance Award agreement.
Summary of Restricted Stock Unit Activity	The following table summarizes RSU activity for the years ended December 31 (number of units and aggregate intrinsic value in thousands): 2018 2017 2016 Number of Units Weighted Average Grant-Date Fair Value Number of Units Weighted Average Grant-Date Fair Value Number of Units Weighted Average Grant-Date Fair Value Units outstanding, beginning of year 2,348 $ 23.47 1,330 $ 20.40 1,139 $ 19.30 Granted 381 46.06 1,731 24.59 718 19.75 Released (772 ) 23.85 (519 ) 18.85 (414 ) 15.91 Forfeited (302 ) 24.73 (194 ) 24.61 (113 ) 21.65 Units outstanding, end of year 1,655 28.34 2,348 23.47 1,330 20.40 Aggregate intrinsic value at year end $ 72,406
Summary of the Company's Stock Options Activity	The following table summarizes stock option activity for the years ended December 31 (number of options in thousands): 2018 2017 2016 Number of Options Weighted Average Exercise Price Number of Options Weighted Average Exercise Price Number of Options Weighted Average Exercise Price Options outstanding, beginning of year 804 $ 4.99 1,008 $ 5.40 1,103 $ 5.37 Granted 6,366 28.58 — — — — Exercised (664 ) 5.09 (198 ) 6.99 (95 ) 5.02 Expired / terminated (48 ) 4.55 (6 ) 8.32 — — Options outstanding, end of year 6,458 28.24 804 4.99 1,008 5.40 Options exercisable, end of year 92 4.45 775 5.00 977 5.42
Summary of Stock Options Outstanding and Exercisable	The following table summarizes information about stock options that were fully vested or expected to vest as of December 31, 2018 (number of options in thousands): Options Outstanding Options Exercisable Range of Exercise Price Number of Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Number of Options Exercisable Weighted Weighted Average Remaining Contractual Life (Years) $4.20 - $6.30 92 $ 4.45 1.54 92 $ 4.45 1.54
Reported Share-Based Compensation	account for stock-based compensation using the fair-value method. Reported stock-based compensation was classified as follows for the years ended December 31 (in thousands): 2018 2017 2016 Cost of product and service sales $ 511 $ 508 $ 342 Sales, general and administrative expenses 12,710 9,047 5,707 Research and development expenses 8,658 6,055 3,320 Total stock-based compensation expense $ 21,879 $ 15,610 $ 9,369 Income tax benefit $ 4,049 $ 5,791 $ 3,526

Business Acquisitions (Tables)

Business Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The major classes of assets to which we allocated the purchase price were as follows (in thousands): Re-acquired distribution rights $ 2,100 Customer relationships 400 Goodwill 1,650 Total purchase price $ 4,150 The major classes of assets and liabilities to which we allocated the purchase price were as follows (in thousands): Accounts receivable $ 12 Property and equipment 46 Developed technology 5,800 Goodwill 2,703 Deferred income tax liabilities, net (1,074 ) Total purchase price $ 7,487 The major classes of assets and liabilities to which we have allocated the purchase price were as follows (in thousands): Accounts receivable $ 1,776 Inventory 2,626 Prepaid expenses and other assets 362 Property and equipment 459 Contract assets 1,472 Intangible assets 4,510 Goodwill 10,285 Accounts payable and accrued liabilities (3,345 ) Deferred revenue (543 ) Total purchase price $ 17,602
Business Acquisition, Pro Forma Information, Nonrecurring Adjustments	These unaudited pro forma results of operations are presented for informational purposes only as required by U.S. GAAP, and do not include any anticipated cost savings or other effects of future integration efforts associated with the Company's acquisition strategy to secure major city customer relationships. As such, they may not be indicative of the results we would have achieved if the acquisition had taken place on January 1, 2017, nor are they indicative of future results of operations (in thousands, except per share amounts): For the Years Ended December 31, 2018 2017 Net sales $ 423,890 $ 352,985 Net income (loss) $ 27,035 $ (2,145 ) Net income (loss) per share: Basic $ 0.49 $ (0.04 ) Diluted $ 0.47 $ (0.04 )

Segment Data (Tables)

Segment Data (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Summary of Operational Information Relative to the Company's Reportable Segments	Information relative to our reportable segments was as follows (in thousands): For the year ended December 31, 2018 TASER Software and Sensors Total Net sales from products $ 253,115 $ 74,520 $ 327,635 Net sales from services — 92,433 92,433 Net sales 253,115 166,953 420,068 Cost of product sales 80,354 58,983 139,337 Cost of service sales — 22,148 22,148 Cost of sales 80,354 81,131 161,485 Gross margin 172,761 85,822 258,583 Sales, general and administrative 90,910 65,976 156,886 Research and development 17,012 59,844 76,856 Income (loss) from operations $ 64,839 $ (39,998 ) $ 24,841 For the year ended December 31, 2017 TASER Software and Sensors Total Net sales from products (1) $ 234,512 $ 51,347 $ 285,859 Net sales from services (1) — 57,939 57,939 Net sales (1) 234,512 109,286 343,798 Cost of product sales 72,054 45,943 117,997 Cost of service sales — 18,713 18,713 Cost of sales 72,054 64,656 136,710 Gross margin 162,458 44,630 207,088 Sales, general and administrative (1) 78,202 60,490 138,692 Research and development 8,377 46,996 55,373 Income (loss) from operations $ 75,879 $ (62,856 ) $ 13,023 For the year ended December 31, 2016 TASER Software and Sensors Total Net sales from products (1) $ 202,644 $ 35,929 $ 238,573 Net sales from services (1) — 29,672 29,672 Net sales (1) 202,644 65,601 268,245 Cost of product sales 61,930 29,606 91,536 Cost of service sales — 6,173 6,173 Cost of sales 61,930 35,779 97,709 Gross margin 140,714 29,822 170,536 Sales, general and administrative (1) 63,617 44,459 108,076 Research and development 5,887 24,722 30,609 Income (loss) from operations $ 71,210 $ (39,359 ) $ 31,851 (1) Amounts for the years ended December 31, 2017 and 2016 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605.

Selected Quarterly Financial _2

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data	Selected quarterly financial data for years ended December 31, 2018 and 2017 follows (in thousands, except per share data): Quarter Ended March 31, June 30, September 30, December 31, 2018 2018 2018 2018 (1) Net sales $ 101,215 $ 99,226 $ 104,836 $ 114,791 Gross margin 64,461 63,143 65,633 65,346 Net income 12,926 8,485 5,711 2,083 Earnings per share (2) : Basic $ 0.24 $ 0.15 $ 0.10 $ 0.04 Diluted $ 0.24 $ 0.15 $ 0.10 $ 0.03 Quarter Ended March 31, June 30, September 30, December 31, 2017 2017 2017 2017 Net sales (3) $ 79,242 $ 79,643 $ 90,262 $ 94,651 Gross margin 48,670 45,637 49,765 63,016 Net income (loss) (3) 4,580 2,276 422 (2,071 ) Earnings (loss) per share (2) (3) : Basic $ 0.09 $ 0.04 $ 0.01 $ (0.04 ) Diluted $ 0.09 $ 0.04 $ 0.01 $ (0.04 ) (1) Results of operations for the three months ended December 31, 2018 included out of period adjustments related to prior quarterly periods in 2018 and 2017. The aggregate out of period adjustment was approximately $1.8 million , reflecting a $0.9 million decrease to net sales, a $1.3 million increase to sales, general and administrative expense, and a $0.4 million decrease to provision for income taxes. Based on our quantitative and qualitative analysis, we do not consider the out of period impact to be material to our financial position or results of operations for any prior periods or for the quarter or year ended December 31, 2018. (2) Basic and diluted earnings per share are computed independently for each of the quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted earnings per share. (3) Amounts for 2017 have not been adjusted under the modified retrospective method of adoption of Topic 606, and are presented consistent with the prior period amounts reported under ASC 605.

Supplemental Disclosure to Ca_2

Supplemental Disclosure to Cash Flows (Tables)	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Non-Cash and Other Cash Flow Information	Supplemental non-cash and other cash flow information were as follows as of and for the years ended December 31 (in thousands): 2018 2017 2016 Supplemental disclosures: Cash and cash equivalents $ 349,462 $ 75,105 $ 40,651 Restricted cash $ 1,565 $ 3,333 $ 3,317 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 351,027 $ 78,438 $ 43,968 Cash paid for income taxes, net of refunds $ 10,609 $ 11,487 $ 14,048 Non-cash transactions: Contingent consideration related to business combinations $ — $ 1,007 $ 3,325 Property and equipment purchases in accounts payable 501 133 82 Non-cash purchase consideration related to business combinations 12,508 — — Purchase of assets under capital lease obligations — — 134

Organization and Summary of S_4

Organization and Summary of Significant Accounting Policies - Additional Information (Detail)	May 24, 2018trancheshares	Dec. 31, 2018USD ($)sourcedepository_institutionsegmentshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2011shares	Jan. 01, 2019USD ($)	Jan. 01, 2018USD ($)
Summary Of Significant Accounting Policy [Line Items]
Impairment losses		$ 2,000,000	$ 1,000,000	$ 0
Number of revenue sources | source		2
Cost of sales		$ 161,485,000	136,710,000	97,709,000
Warranty period		1 year
Research and development costs		$ 76,856,000	55,373,000	$ 30,609,000
Allowance for doubtful accounts		$ (1,882,000)	(754,000)
Number of depository institutions | depository_institution		4
Aggregate balances in depository institution accounts		$ 342,300,000
Cash surrender value of corporate-owned life insurance policies		$ 3,596,000	$ 3,846,000
Number of reportable segments of company | segment		2
New option granted (in shares) | shares		0	0	0
Retained earnings		$ 171,383,000	$ 123,185,000				$ 142,179,000
Cumulative effect of applying a change in accounting principle		18,993,000	178,000
Advertising
Summary Of Significant Accounting Policy [Line Items]
Cost of sales		1,100,000	500,000	$ 400,000
Additional Paid-in Capital
Summary Of Significant Accounting Policy [Line Items]
Cumulative effect of applying a change in accounting principle			475,000
Retained Earnings
Summary Of Significant Accounting Policy [Line Items]
Cumulative effect of applying a change in accounting principle		18,993,000	$ (297,000)
Impact of Adoption of Topic 606 on Opening Balance Sheet | Accounting Standards Update 2014-09
Summary Of Significant Accounting Policy [Line Items]
Retained earnings		$ 19,000,000					$ 18,994,000
Performance Shares
Summary Of Significant Accounting Policy [Line Items]
New option granted (in shares) | shares	6,365,856				1,000,000
Chief Executive Officer
Summary Of Significant Accounting Policy [Line Items]
Number of vesting tranches of share-based awards | tranche	12
Subsequent Event | Restatement Adjustment | Accounting Standards Update 2016-02
Summary Of Significant Accounting Policy [Line Items]
Operating Lease, Right-of-Use Asset						$ 11,000,000
Operating Lease, Liability						$ 12,000,000

Organization and Summary of S_5

Organization and Summary of Significant Accounting Policies - Summary of Changes in Estimated Product Warranty Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement in Standard and Extended Product Warranty
Balance, January 1	$ 644	$ 780	$ 314
Utilization of reserve	(458)	(245)	(155)
Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties	712	109	621
Balance, December 31	$ 898	$ 644	$ 780

Organization and Summary of S_6

Organization and Summary of Significant Accounting Policies - Net Sales by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Percentage of net sales by geographic area									100.00%	100.00%	100.00%
Net sales	$ 114,791	$ 104,836	$ 99,226	$ 101,215	$ 94,651	$ 90,262	$ 79,643	$ 79,242	$ 420,068	$ 343,798	$ 268,245
United States
Segment Reporting Information [Line Items]
Percentage of net sales by geographic area									79.80%	82.30%	81.60%
Net sales									$ 335,310	$ 282,810	$ 218,757
Other Countries
Segment Reporting Information [Line Items]
Percentage of net sales by geographic area									20.20%	17.70%	18.40%
Net sales									$ 84,758	$ 60,988	$ 49,488

Organization and Summary of S_7

Organization and Summary of Significant Accounting Policies - Weighted Average Number of Shares Outstanding and Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator for basic and diluted earnings per share:
Net income	$ 2,083	$ 5,711	$ 8,485	$ 12,926	$ (2,071)	$ 422	$ 2,276	$ 4,580	$ 29,205	$ 5,207	$ 17,297
Denominator:
Weighted average shares outstanding—basic (in shares)									56,392	52,726	52,667
Dilutive effect of stock-based awards (in shares)									1,530	1,172	869
Diluted weighted average shares outstanding (in shares)									57,922	53,898	53,536
Anti-dilutive stock-based awards excluded (in shares)									6,757	386	443
Net income per common share:
Basic (in dollars per share)	$ 0.04	$ 0.10	$ 0.15	$ 0.24	$ (0.04)	$ 0.01	$ 0.04	$ 0.09	$ 0.52	$ 0.10	$ 0.33
Diluted (in dollars per share)	$ 0.03	$ 0.10	$ 0.15	$ 0.24	$ (0.04)	$ 0.01	$ 0.04	$ 0.09	$ 0.50	$ 0.10	$ 0.32

Organization and Summary of S_8

Organization and Summary of Significant Accounting Policies Organization and Summary of Significant Accounting Policies - Share-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2018$ / shares
Accounting Policies [Abstract]
Volatility	47.71%
Risk-free interest rate	2.98%
Dividend rate	0.00%
Expected life of options	9 years 9 months 3 days
Weighted average fair value (in dollars per share)	$ 38,640

Organization and Summary of S_9

Organization and Summary of Significant Accounting Policies - Share-based Compensation Plans (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 26, 2016
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Illiquidity rate	9.20%
Post exercise holding period	2 years 6 months
Service Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration Period	10 years
Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration Period	10 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration Period	10 years
Minimum | Service Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Minimum | Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Maximum | Service Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Maximum | Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future grants (in shares)		1
Shares available for future grants (in shares)	1.7

Revenues - Additional Informati

Revenues - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Unbilled Receivables, Current	$ 17,300									$ 17,300
Payment due date from date of invoice									30 days
Retained earnings	171,383				$ 123,185					171,383	$ 123,185		$ 142,179
Net sales	114,791	$ 104,836	$ 99,226	$ 101,215	$ 94,651	$ 90,262	$ 79,643	$ 79,242		420,068	343,798	$ 268,245
Sales, general and administrative										156,886	138,692	$ 108,076
Impact of Adoption of Topic 606 on Opening Balance Sheet | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings	$ 19,000									19,000			$ 18,994
Net sales										5,000
Sales, general and administrative										(3,600)
Taser 60 Plan
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales										48,200	40,700
Interest Income (Expense), Net										1,300	$ 700
Sales, general and administrative expenses
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Amortization related to deferred commissions										$ 5,300
Minimum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, remaining performance obligation to be recognized in the next twelve months, percent	15.00%									15.00%
Maximum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, remaining performance obligation to be recognized in the next twelve months, percent	20.00%									20.00%

Revenues - Impact of Adopting N

Revenues - Impact of Adopting New Revenue Recognition Standard (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts and notes receivable, net	$ 130,579	$ 84,979	$ 56,064
Contract assets, net	13,960	5,512	0
Prepaid expenses and other current assets	30,391	23,699	21,696
Total current assets	558,155	114,190	205,192
Deferred income tax assets, net	19,347	10,597	15,755
Long-term notes receivable	40,230	23,900	36,877
Other assets	22,999	20,689	15,366
Total assets	719,540	169,376	338,112
Accrued liabilities	41,092	26,014	23,502
Contract with customer, liability, current	107,016	71,264	70,401
Total current liabilities	166,011	97,278	107,950
Deferred revenue, net of current portion	74,417	56,130	54,881
Total liabilities	252,216	153,408	170,668
Retained earnings	171,383	142,179	123,185
Total stockholders’ equity	467,324	142,179	167,444	$ 150,888	$ 157,004
Total liabilities and stockholders’ equity	719,540	295,587	338,112
December 31, 2017 (As reported)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts and notes receivable, net			56,064
Contract assets, net			0
Prepaid expenses and other current assets			21,696
Total current assets			77,760
Deferred income tax assets, net			15,755
Long-term notes receivable			36,877
Other assets			15,366
Total assets			145,758
Accrued liabilities			23,502
Contract with customer, liability, current			70,401
Total current liabilities			93,903
Deferred revenue, net of current portion			54,881
Total liabilities			148,784
Retained earnings			123,185
Total stockholders’ equity			123,185
Total liabilities and stockholders’ equity			$ 271,969
Impact of Adoption of Topic 606 on Opening Balance Sheet | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts and notes receivable, net		28,915
Contract assets, net		5,512
Prepaid expenses and other current assets		2,003
Total current assets		36,430
Deferred income tax assets, net		(5,158)
Long-term notes receivable		(12,977)
Other assets		5,323
Total assets		23,618
Accrued liabilities		2,512
Contract with customer, liability, current		863
Total current liabilities		3,375
Deferred revenue, net of current portion		1,249
Total liabilities		4,624
Retained earnings	$ 19,000	18,994
Total stockholders’ equity		18,994
Total liabilities and stockholders’ equity		$ 23,618

Revenues - Revenues by Product

Revenues - Revenues by Product and Services Offerings (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers	$ 114,791,000	$ 104,836,000	$ 99,226,000	$ 101,215,000	$ 94,651,000	$ 90,262,000	$ 79,643,000	$ 79,242,000	$ 420,068,000	$ 343,798,000	$ 268,245,000
TASER 7
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									7,358,000	0
TASER X26P
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									70,638,000	64,426,000
TASER X2
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									78,837,000	81,417,000
TASER Pulse and Bolt
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									5,182,000	4,340,000
Cartridges
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									68,258,000	63,203,000
Axon Body
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									21,883,000	15,184,000
Axon Flex
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									6,509,000	10,083,000
Axon Fleet
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									12,527,000	2,954,000
Axon Dock
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									10,706,000	9,736,000
Axon Evidence and cloud services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									90,291,000	57,841,000
TASER Cam
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									3,871,000	3,358,000
Extended warranties
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									27,613,000	19,536,000
Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									16,395,000	11,720,000
TASER
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									253,115,000	234,512,000	202,644,000
TASER | TASER 7
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									7,358,000	0
TASER | TASER X26P
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									70,638,000	64,426,000
TASER | TASER X2
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									78,837,000	81,417,000
TASER | TASER Pulse and Bolt
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									5,182,000	4,340,000
TASER | Cartridges
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									68,258,000	63,203,000
TASER | Axon Body
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
TASER | Axon Flex
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
TASER | Axon Fleet
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
TASER | Axon Dock
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
TASER | Axon Evidence and cloud services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
TASER | TASER Cam
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
TASER | Extended warranties
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									15,753,000	12,426,000
TASER | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									7,089,000	8,700,000
Software and Sensors
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									166,953,000	109,286,000	$ 65,601,000
Software and Sensors | TASER 7
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
Software and Sensors | TASER X26P
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
Software and Sensors | TASER X2
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
Software and Sensors | TASER Pulse and Bolt
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
Software and Sensors | Cartridges
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									0	0
Software and Sensors | Axon Body
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									21,883,000	15,184,000
Software and Sensors | Axon Flex
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									6,509,000	10,083,000
Software and Sensors | Axon Fleet
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									12,527,000	2,954,000
Software and Sensors | Axon Dock
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									10,706,000	9,736,000
Software and Sensors | Axon Evidence and cloud services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									90,291,000	57,841,000
Software and Sensors | TASER Cam
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									3,871,000	3,358,000
Software and Sensors | Extended warranties
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									11,860,000	7,110,000
Software and Sensors | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customers									$ 9,306,000	$ 3,020,000

Revenues - Summary of Deferred

Revenues - Summary of Deferred Revenue (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Current	$ 107,016	$ 71,264	$ 70,401
Long-Term	74,417	$ 56,130	54,881
Total	181,433		125,282
TASER
Disaggregation of Revenue [Line Items]
Current	22,152		16,665
Long-Term	32,445		30,020
Total	54,597		46,685
Software and Sensors
Disaggregation of Revenue [Line Items]
Current	84,864		53,736
Long-Term	41,972		24,861
Total	126,836		78,597
Warranty
Disaggregation of Revenue [Line Items]
Current	21,070		18,794
Long-Term	23,363		22,814
Total	44,433		41,608
Warranty | TASER
Disaggregation of Revenue [Line Items]
Current	12,797		12,501
Long-Term	16,847		18,619
Total	29,644		31,120
Warranty | Software and Sensors
Disaggregation of Revenue [Line Items]
Current	8,273		6,293
Long-Term	6,516		4,195
Total	14,789		10,488
Hardware
Disaggregation of Revenue [Line Items]
Current	30,233		21,120
Long-Term	40,283		26,182
Total	70,516		47,302
Hardware | TASER
Disaggregation of Revenue [Line Items]
Current	9,355		4,164
Long-Term	15,598		11,401
Total	24,953		15,565
Hardware | Software and Sensors
Disaggregation of Revenue [Line Items]
Current	20,878		16,956
Long-Term	24,685		14,781
Total	45,563		31,737
Software and Sensors Services | Software and Sensors
Disaggregation of Revenue [Line Items]
Current	55,713		30,487
Long-Term	10,771		5,885
Total	$ 66,484		$ 36,372

Revenues - Contract Assets, Con

Revenues - Contract Assets, Contract Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Contract assets, net	$ 13,960
Contract liability (deferred revenue)	181,433	$ 125,282
Revenue recognized in the period from:
Amounts included in contract liabilities at the beginning of the period	$ 63,475

Revenues - Remaining Performanc

Revenues - Remaining Performance Obligations (Details) $ in Millions	Dec. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 900
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	5 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	7 years

Revenues - Cost to Obtain Contr

Revenues - Cost to Obtain Contracts with Customer (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Current deferred commissions	$ 7,062
Deferred commissions, net of current portion	15,530	$ 12,200	$ 6,803
Deferred sales commission	$ 22,592

Cash, Cash Equivalents, and Inv

Cash, Cash Equivalents, and Investments - Summary of Cash, Cash Equivalents and Held-to-Maturity Investments by Type (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Amortized Cost	$ 349,462	$ 81,967
Gross Unrealized Losses	0	(6)
Fair Value	349,462	81,961
Cash and Cash Equivalents	349,462	75,105
Short-term investments	0	6,862
Level 1
Restricted Cash and Cash Equivalents Items [Line Items]
Amortized Cost		27,516
Gross Unrealized Losses		(6)
Fair Value		27,510
Cash and Cash Equivalents		20,884
Short-term investments		6,632
Level 2
Restricted Cash and Cash Equivalents Items [Line Items]
Amortized Cost		992
Gross Unrealized Losses		0
Fair Value		992
Cash and Cash Equivalents		762
Short-term investments		230
Level 2 | State and municipal obligations
Restricted Cash and Cash Equivalents Items [Line Items]
Amortized Cost		992
Gross Unrealized Losses		0
Fair Value		992
Cash and Cash Equivalents		762
Short-term investments		230
Cash
Restricted Cash and Cash Equivalents Items [Line Items]
Amortized Cost	144,095	53,459
Gross Unrealized Losses	0	0
Fair Value	144,095	53,459
Cash and Cash Equivalents	144,095	53,459
Short-term investments	0	0
Money market funds | Level 1
Restricted Cash and Cash Equivalents Items [Line Items]
Amortized Cost	205,367	20,884
Gross Unrealized Losses	0	0
Fair Value	205,367	20,884
Cash and Cash Equivalents	205,367	20,884
Short-term investments	$ 0	0
Corporate bonds | Level 1
Restricted Cash and Cash Equivalents Items [Line Items]
Amortized Cost		6,632
Gross Unrealized Losses		(6)
Fair Value		6,626
Cash and Cash Equivalents		0
Short-term investments		$ 6,632

Inventory (Detail)

Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventory, finished goods, trial and evaluation hardware	$ 1,400	$ 1,400
Raw materials	19,670	20,119
Finished goods	14,093	25,346
Total inventory	$ 33,763	$ 45,465

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total cost	$ 77,778	$ 67,649
Less: Accumulated depreciation	(39,885)	(36,477)
Property and equipment, net	37,893	31,172
Land
Property, Plant and Equipment [Line Items]
Total cost	2,900	2,900
Building and leasehold improvements
Property, Plant and Equipment [Line Items]
Total cost	$ 19,578	18,383
Building and leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Building and leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	39 years
Production equipment
Property, Plant and Equipment [Line Items]
Total cost	$ 19,817	19,075
Production equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Production equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years
Computers, equipment and software
Property, Plant and Equipment [Line Items]
Total cost	$ 8,392	6,780
Computers, equipment and software | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Computers, equipment and software | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Furniture and office equipment
Property, Plant and Equipment [Line Items]
Total cost	$ 6,529	5,262
Furniture and office equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Furniture and office equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years
Vehicles
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Total cost	$ 1,385	1,057
Website development costs
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Total cost	$ 687	687
Capitalized internal-use software development costs
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Total cost	$ 3,670	3,695
Construction-in-process
Property, Plant and Equipment [Line Items]
Total cost	$ 14,820	$ 9,810

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense relative to property and equipment	$ 4,900	$ 3,400	$ 2,500
Cost of products sold and services provided	161,485	136,710	97,709
Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Cost of products sold and services provided	$ 1,400	$ 1,100	$ 700

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Changes in carrying amount of goodwill
Balance, January 1, 2018	$ 14,927
Goodwill acquired	10,285
Foreign currency translation adjustments	(231)
Balance, December 31, 2018	24,981
TASER
Changes in carrying amount of goodwill
Balance, January 1, 2018	1,453
Goodwill acquired	0
Foreign currency translation adjustments	(115)
Balance, December 31, 2018	1,338
Software and Sensors
Changes in carrying amount of goodwill
Balance, January 1, 2018	13,474
Goodwill acquired	10,285
Foreign currency translation adjustments	(116)
Balance, December 31, 2018	$ 23,643

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets Other than Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 26,727	$ 24,253
Accumulated Amortization	(12,650)	(7,202)
Total	14,077	17,051
Not amortized, Gross Carrying Amount	1,858	1,772
Intangible assets, Gross Carrying Amount	28,585	26,025
Intangible Assets, Net Carrying Amount	15,935	18,823
Amortization of intangible assets	5,700	4,700	$ 900
TASER trademark
Acquired Indefinite-lived Intangible Assets [Line Items]
Not amortized, Gross Carrying Amount	900	900
Patents and trademarks pending
Acquired Indefinite-lived Intangible Assets [Line Items]
Not amortized, Gross Carrying Amount	958	872
Domain names
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	3,161	3,161
Accumulated Amortization	(732)	(428)
Total	$ 2,429	2,733
Domain names | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	5 years
Domain names | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	10 years
Issued patents
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 2,940	2,697
Accumulated Amortization	(1,106)	(913)
Total	$ 1,834	1,784
Issued patents | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	4 years
Issued patents | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	15 years
Issued trademarks
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 1,053	860
Accumulated Amortization	(599)	(397)
Total	$ 454	463
Issued trademarks | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	3 years
Issued trademarks | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	11 years
Customer relationships
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 3,701	1,377
Accumulated Amortization	(880)	(451)
Total	$ 2,821	926
Customer relationships | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	4 years
Customer relationships | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	8 years
Non-compete agreements
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 540	556
Accumulated Amortization	(439)	(346)
Total	$ 101	210
Non-compete agreements | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	3 years
Non-compete agreements | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	4 years
Developed technology
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 13,404	13,469
Accumulated Amortization	(7,081)	(3,956)
Total	$ 6,323	9,513
Developed technology | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	3 years
Developed technology | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	7 years
Re-acquired distribution rights
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	2 years
Amortized, Gross Carrying Amount	$ 1,928	2,133
Accumulated Amortization	(1,813)	(711)
Total	$ 115	$ 1,422

Goodwill and Intangible asset_4

Goodwill and Intangible assets - Estimated Amortization Expense of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
2,019	$ 3,463
2,020	3,294
2,021	2,852
2,022	1,211
2,023	934
Thereafter	2,323
Total	$ 14,077	$ 17,051

Other Long-Term Assets (Details

Other Long-Term Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Cash surrender value of corporate-owned life insurance policies	$ 3,596		$ 3,846
Deferred commissions, net of current portion	15,530	$ 12,200	6,803
Restricted cash	661		3,333
Prepaid expenses, deposits and other	3,212		1,384
Total other long-term assets	$ 22,999	$ 20,689	$ 15,366

Other Long-Term Assets - Additi

Other Long-Term Assets - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred sales commission	$ 22,592
Deferred commissions, net of current portion	15,530	$ 12,200	$ 6,803
Accounting Standards Update 2014-09 | Impact of Adoption of Topic 606 on Opening Balance Sheet
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred sales commission		7,300
Deferred commissions, net of current portion		$ 5,400
Customer B
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 600

Accrued Liabilities (Detail)

Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accrued salaries, benefits and bonus	$ 19,063		$ 8,957
Accrued professional, consulting and lobbying fees	4,894		3,870
Accrued warranty expense	898		644	$ 780	$ 314
Accrued income and other taxes	4,167		2,558
Other accrued expenses	12,070		7,473
Accrued liabilities	$ 41,092	$ 26,014	$ 23,502

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 13, 2018	Feb. 22, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Rent expense under operating lease			$ 4,200	$ 2,900	$ 1,800
Purchase of intangible assets			558	$ 1,024	$ 3,495
Initial deposit	$ 200
Open purchase order			66,600
Self-insurance on product claim			5,000
Letters of credit outstanding amount			3,100
Surety Bond
Loss Contingencies [Line Items]
Bonds outstanding			14,100
Expiring May 2018 | Surety Bond
Loss Contingencies [Line Items]
Letters of credit outstanding amount			3,100
Expiring in 2018 | Surety Bond
Loss Contingencies [Line Items]
Bonds outstanding			400
Expiring in 2020 | Surety Bond
Loss Contingencies [Line Items]
Bonds outstanding			700
Expiring in 2021 | Surety Bond
Loss Contingencies [Line Items]
Outstanding surety bonds expected to be released during period			2,300
Expiring in 2022 | Surety Bond
Loss Contingencies [Line Items]
Outstanding surety bonds expected to be released during period			3,100
Expiring in 2023 and thereafter | Surety Bond
Loss Contingencies [Line Items]
Outstanding surety bonds expected to be released during period			$ 7,600
Minimum
Loss Contingencies [Line Items]
Operating leases, term (ranging from less than one year)			1 year
Maximum
Loss Contingencies [Line Items]
Operating leases, term (ranging from less than one year)			5 years
Lease Agreements
Loss Contingencies [Line Items]
Useful Life	84 years
Purchase of intangible assets	$ 13,100
Plan | Subsequent Event
Loss Contingencies [Line Items]
Prepaid rent under the lease		$ 10,900

Commitments and Contingencies_2

Commitments and Contingencies - Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,019	$ 3,670
2,020	3,572
2,021	2,961
2,022	2,001
2,023	573
Total minimum lease payments	12,777
Capital
2,019	40
2,020	36
2,021	0
2,022	0
2,023	0
Thereafter	0
Total minimum lease payments	76
Less: Amount representing interest	(6)
Capital lease obligation	$ 70

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Tax cuts and jobs act of 2017, incomplete accounting, provisional income tax expense (benefit)	$ 0.3		$ 7.6
Deferred tax assets, state NOLs	2.5	$ 2.5
Deferred tax assets, federal NOLs	1.5	1.5
Liability for unrecognized tax benefits			5.2
Threshold to favorably impact effective tax rate	5.3	5.3
Unrecognized tax benefits, accrued interest	0.1	0.1	$ 0.1
AUSTRALIA
Income Tax Contingency [Line Items]
Deferred tax assets, foreign NOLs	8.9	8.9
UNITED KINGDOM
Income Tax Contingency [Line Items]
Deferred tax assets, foreign NOLs	1.4	1.4
GERMANY
Income Tax Contingency [Line Items]
Deferred tax assets, foreign NOLs	0.1	0.1
Federal
Income Tax Contingency [Line Items]
Federal research and development credit carry forwards		0.1
State
Income Tax Contingency [Line Items]
Liability for unrecognized tax benefits	$ 0.1	0.1
State | ARIZONA
Income Tax Contingency [Line Items]
State research and development credit carry forwards		$ 9.7

Income Taxes - Income by Region

Income Taxes - Income by Region (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States	$ 25,751	$ 14,978	$ 38,414
Foreign	2,353	783	(6,917)
Income before provision for income taxes	$ 28,104	$ 15,761	$ 31,497

Income Taxes - Significant Comp

Income Taxes - Significant Components of the Provision (Benefit) for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 4,900	$ 6,039	$ 16,346
State	1,377	1,263	1,534
Foreign	228	656	1,050
Total current	6,505	7,958	18,930
Deferred:
Federal	(8,382)	4,539	(4,145)
State	(364)	(1,631)	(977)
Foreign	(3)	(78)	(45)
Total deferred	(8,749)	2,830	(5,167)
Tax impact of unrecorded tax benefits liability	1,143	(234)	437
Provision for income taxes	$ (1,101)	$ 10,554	$ 14,200

Income Taxes - Components of De

Income Taxes - Components of Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax assets:
Net operating loss carryforward	$ 2,347	$ 3,691
Deferred revenue	13,304	9,442
Deferred compensation	858	1,109
Inventory reserve	1,294	702
Non-qualified and non-employee stock option expense	3,758	3,704
Capitalized research and development	0	485
Research and development tax credit carryforward	5,193	3,817
Reserves, accruals, and other	3,094	1,921
Total deferred income tax assets	30,260	24,871
Deferred income tax liabilities:
Depreciation	(2,195)	(2,027)
Amortization	(57)	(1,398)
Other	(1,232)	(256)
Total deferred income tax liabilities	(3,484)	(3,681)
Net deferred income tax assets before valuation allowance	26,776	21,190
Valuation allowance	(7,429)	(5,435)
Net deferred income tax assets	19,347	15,755
Deferred Tax Assets, Amortization	$ 412	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the Company's Effective Income Tax Rate to the Federal Statutory Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal income tax at the statutory rate	$ 5,902	$ 5,518	$ 11,024
State income taxes, net of federal benefit	(215)	339	889
Difference between statutory and foreign tax rates	7	(560)	1,521
Permanent differences	725	300	(457)
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount	1,167	0	0
Research and development	(6,908)	(2,380)	(1,928)
Return to provision adjustment	1,780	23	327
Change in liability for unrecognized tax benefits	1,768	7	700
Excess stock-based compensation benefit	(8,907)	(1,819)	(77)
Change in valuation allowance	1,984	1,949	1,779
Tax effects of intercompany transactions	(1,004)	277	(630)
Adjustments to deferreds resulting from enactment of new tax law	0	7,601	0
Other	592	(147)	(208)
Provision for income taxes	$ (1,101)	$ 10,554	$ 14,200
Effective tax rate	(3.90%)	66.90%	45.10%
Excess tax benefit from stock-based compensation			$ 1,438

Income Taxes - Roll Forward of

Income Taxes - Roll Forward of Liability for Unrecognized Tax Benefits Exclusive of Accrued Interest (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits
Balance, beginning of period	$ 4,243	$ 4,050	$ 3,396
Increase in previous year tax positions	213	379	206
Increase in current year tax positions	1,982	587	448
Decrease due to lapse of statutes of limitations	(380)	(773)	0
Balance, end of period	$ 6,058	$ 4,243	$ 4,050

Line of Credit - Additional Inf

Line of Credit - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Borrowings under the line of credit agreement	$ 0	$ 0
Letters of credit outstanding amount	3,100,000
Available borrowing under letter of credit	$ 96,900,000
Maximum ratio of total liabilities to tangible net worth	2.50
Company's tangible net worth ratio	0.001
Line of Credit
Debt Instrument [Line Items]
Line of Credit Facility, Increase (Decrease), Net	$ 100,000,000
Line of Credit | Unsecured Revolving Line of Credit
Debt Instrument [Line Items]
Total availability under line of credit agreement	100,000,000
Line of Credit | Letter of Credit
Debt Instrument [Line Items]
Total availability under line of credit agreement	$ 10,000,000
Minimum | Line of Credit | LIBOR
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate	1.00%
Maximum | Line of Credit | LIBOR
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate	1.50%

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock and Preferred Stock (Details)	12 Months Ended
	Dec. 31, 2018class_of_stock$ / sharesshares	Dec. 31, 2017$ / sharesshares
Equity [Abstract]
Number of classes of stock | class_of_stock	2
Common stock, par value (in dollars per share) | $ / shares	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000

Stockholders' Equity - Follow-O

Stockholders' Equity - Follow-On Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsidiary, Sale of Stock [Line Items]
Sale of Stock, Price Per Share	$ 53
Net proceeds from equity offering	$ 234,000	$ 233,993	$ 0	$ 0
Public Stock Offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction	4,645,000	300,000
Unwritten Public Stock Offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction	645,000
Sale of Stock, Consideration Received Per Transaction	$ 246,200

Stockholders' Equity - CEO Perf

Stockholders' Equity - CEO Performance Award (Details) $ in Thousands	May 24, 2018trancheshares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017shares	Dec. 31, 2016shares	Dec. 31, 2011shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
New option granted (in shares) | shares		0	0	0
First tranche		$ 2,500,000
Incremental increase		1,000,000
Incremental stock option expense		$ 3,300
Number of Options expected to vest, end of year (in shares) | shares		1,100,000
Weighted average period		7 years 2 months 12 days
Revenue Goal 1		$ 710,058
Adjusted EBITDA Goal 9		125,000
Revenue Goal 2		860,058
Adjusted EBITDA Goal 10		155,000
Revenue Goal 3		1,010,058
Adjusted EBITDA Goal 11		175,000
Revenue Goal 4		1,210,058
Adjusted EBITDA Goal 12		190,000
Revenue Goal 5		1,410,058
Adjusted EBITDA Goal 13		200,000
Revenue Goal 6		1,610,058
Adjusted EBITDA Goal 14		210,000
Revenue Goal 7		1,810,058
Adjusted EBITDA Goal 15		220,000
Revenue Goal 8		2,010,058
Adjusted EBITDA Goal 16		230,000
Total revenue		710,100
Adjusted EBITDA		125,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
New option granted (in shares) | shares	6,365,856				1,000,000
Total unrecognized stock-based compensation expense for operational goals		42,000
Unrecognized expense for the operational goals that were not probable of achievement		$ 200,700
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of vesting tranches of share-based awards | tranche	12

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Options Outstanding and Exercisable (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
$4.20 - $6.30
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Price, lower limit (in dollars per share)	$ 4.20
Range of Exercise Price, Upper limit (in dollars per share)	$ 6.30
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	6,458	804	1,008	1,103
Weighted average exercise price (in dollars per share)	$ 28.24	$ 4.99	$ 5.40	$ 5.37
Number of Options Exercisable (in shares)	92	775	977
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.45	$ 5	$ 5.42
Stock Options | $4.20 - $6.30
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	92
Weighted average exercise price (in dollars per share)	$ 4.45
Weighted average remaining contractual life	1 year 6 months 15 days
Number of Options Exercisable (in shares)	92
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.45
Options Exercisable, Weighted Average Remaining Contractual Life	1 year 6 months 15 days

Stockholders' Equity - Stock-Ba

Stockholders' Equity - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 21,879	$ 15,610	$ 9,369
Tax benefit recorded	4,049	5,791	3,526
Cost of product and service sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	511	508	342
Sales, general and administrative expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	12,710	9,047	5,707
Research and development expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 8,658	$ 6,055	$ 3,320

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 29, 2018	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax payments, for net share settlement of share based award	$ 14,127	$ 3,453	$ 1,772
Incremental stock option expense	$ 3,300
Weighted average period	7 years 2 months 12 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares withheld, for net share settlement of share based award (in shares)	100,000
Tax payments, for net share settlement of share based award	$ 6,200
Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Approximate units of performance restricted stock granted (in shares)	94,000	353,000	79,000
Performance criteria met for approximate units (in shares)	4,000
Approximate units outstanding (in shares)	400,000
Incremental stock option expense	$ 4,800	$ 2,500	$ 2,100
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price on the last trading day of the period (in dollars per share)				$ 43.75
Aggregate intrinsic value, RSUs vested	$ 36,600
Shares withheld, for net share settlement of share based award (in shares)	185,970
Tax payments, for net share settlement of share based award	$ 7,800
Performance criteria met for approximate units (in shares)	772,000	519,000	414,000
Approximate units outstanding (in shares)	1,655,000	2,348,000	1,330,000		1,139,000
Unrecognized stock-based compensation expense related to non-vested stock options	$ 35,900
Weighted average period	2 years 95 days
Minimum | Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of targeted shares earned that can vest	0.00%
Maximum | Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of targeted shares earned that can vest	200.00%

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	May 24, 2018	May 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2011	Dec. 29, 2018	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income and payroll tax payments for net-settled stock awards			$ (14,127)	$ (3,453)	$ (1,772)
Weighted average fair value (in dollars per share)			$ 38,640
New option granted (in shares)			0	0	0
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value, option outstanding			$ 3,600
Aggregate intrinsic value, options exercisable			3,600
Total intrinsic value of options exercised			$ 28,500	$ 3,200	$ 2,000
Shares withheld, for net share settlement of share based award (in shares)			100,000
Common Stock Surrendered to Cover Stock Options Exercised, Shares			29,854
Income and payroll tax payments for net-settled stock awards			$ (6,200)
Common Stock Surrendered to Cover Stock Options Exercised, Value			$ 1,600
Number of Options outstanding, end of year (in shares)			6,458,000	804,000	1,008,000
Weighted average exercise price (in dollars per share)			$ 28.24	$ 4.99	$ 5.40			$ 5.37
New option granted (in shares)			6,366,000	0	0
Number of Options exercisable, end of year (in shares)			92,000	775,000	977,000
Non-Vested Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options outstanding, end of year (in shares)			6,365,856
Weighted average exercise price (in dollars per share)			$ 28.58
Weighted average fair value (in dollars per share)			$ 38.64
Weighted average remaining contractual life			9 years 274 days
Aggregate intrinsic value of unvested options			$ 96,600
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
New option granted (in shares)	6,365,856					1,000,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price on the last trading day of the period (in dollars per share)							$ 43.75
Shares withheld, for net share settlement of share based award (in shares)			185,970
Income and payroll tax payments for net-settled stock awards			$ (7,800)
Public Stock Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in transaction		4,645,000	300,000

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of the Company's Stock Options Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding
Number of Option, Granted (in shares)	0	0	0
Number of Options expected to vest, end of year (in shares)	1,100,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding
Number of Options outstanding, beginning of year (in shares)	804,000	1,008,000	1,103,000
Number of Option, Granted (in shares)	6,366,000	0	0
Number of Options, Exercised (in shares)	(664,000)	(198,000)	(95,000)
Number of Options, Expired / terminated (in shares)	(48,000)	(6,000)	0
Number of Options outstanding, end of year (in shares)	6,458,000	804,000	1,008,000
Number of Options exercisable, end of year (in shares)	92,000	775,000	977,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Options outstanding, beginning of year (in dollars per share)	$ 4.99	$ 5.40	$ 5.37
Weighted Average Exercise Price, Granted (in dollars per share)	28.58	0	0
Weighted Average Exercise Price, Exercised (in dollars per share)	5.09	6.99	5.02
Weighted Average Exercise Price, Expired / terminated (in dollars per share)	4.55	8.32	0
Weighted Average Exercise Price, Options outstanding, end of year (in dollars per share)	28.24	4.99	5.40
Weighted Average Exercise Price, Options exercisable, end of year (in dollars per share)	$ 4.45	$ 5	$ 5.42

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Detail) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding
Number of Units outstanding, beginning of year (in shares)	2,348	1,330	1,139
Number of Units, Granted (in shares)	381	1,731	718
Number of Units, Released (in shares)	(772)	(519)	(414)
Number of Units, Forfeited (in shares)	(302)	(194)	(113)
Number of Units outstanding, end of year (in shares)	1,655	2,348	1,330
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Grant Date Fair Value, Units outstanding, beginning of year (in dollars per share)	$ 23.47	$ 20.40	$ 19.30
Weighted Average Grant Date Fair Value, Granted (in dollars per share)	46.06	24.59	19.75
Weighted Average Grant Date Fair Value, Released (in dollars per share)	23.85	18.85	15.91
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share)	24.73	24.61	21.65
Weighted Average Grant Date Fair Value, Units outstanding, end of year (in dollars per share)	$ 28.34	$ 23.47	$ 20.40
Aggregate intrinsic value at year end	$ 72,406

Stockholders' Equity - Stock Re

Stockholders' Equity - Stock Repurchase Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Feb. 29, 2016
Equity, Class of Treasury Stock [Line Items]
Remaining authorized repurchase amount			$ 16,300,000
2016 Stock Incentive Plan
Equity, Class of Treasury Stock [Line Items]
Outstanding common stock repurchase program authorized amount				$ 50,000,000
Purchase of common stock shares (in shares)	1,800,000
Total cost	$ 33,700,000
Average cost of repurchase (in dollars per share)	$ 18.90
Remaining authorized repurchase amount		$ 16,300,000

Stockholders' Equity - Stock-_2

Stockholders' Equity - Stock-based Compensation Plans (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 26, 2016
Service Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration Period	10 years
Service Based Restricted Stock Unit | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Service Based Restricted Stock Unit | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration Period	10 years
Performance Based Restricted Stock Unit | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Performance Based Restricted Stock Unit | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration Period	10 years
2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future grants (in shares)		1
Shares available for future grants (in shares)	1.7

Stockholders' Equity - Stock In

Stockholders' Equity - Stock Incentive Plan (Details)	Feb. 01, 2019shares
Subsequent Event | 2019 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	6,000,000

Stockholders' Equity - eXponent

Stockholders' Equity - eXponential Stock Performance Plan (Details) $ in Billions	12 Months Ended
	Dec. 31, 2018USD ($)trancheshares	Dec. 31, 2017shares	Dec. 31, 2016shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
New option granted (in shares) | shares	0	0	0
First tranche	$ 2.5
Incremental increase	$ 1
eXponential Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
New option granted (in shares) | shares	5,100,000
Number of vesting tranches of share-based awards | tranche	12
First tranche	$ 2.5
Incremental increase	$ 1

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - Officer - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Software Licensing and Subscription
Related Party Transaction [Line Items]
Annual payments	$ 1.8	$ 1.2	$ 0.8
Consulting
Related Party Transaction [Line Items]
Outstanding payables due to related party		$ 0

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Deferral percentage of base salary (up to)	80.00%
Deferral percentage of other compensation (up to)	100.00%
Employee deferrals deemed vested percentage upon contribution	100.00%
Company's contributions to the plan	$ 3.2	$ 2.5	$ 1.6

Business Acquisitions - Dextro,

Business Acquisitions - Dextro, Inc. Acquisition (Details) - USD ($)	Feb. 08, 2017	Dec. 31, 2018	Dec. 31, 2017
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill		$ 24,981,000	$ 14,927,000
Dextro, Inc.
Business Acquisition [Line Items]
Total purchase price	$ 7,500,000
Payments to acquire businesses, net	7,500,000
Contingent liability	1,000,000
Business combination, liabilities arising from contingencies, amount recognized		$ 600,000
Additional contingent consideration arrangements	$ 1,400,000
Intangible assets, weighted average useful life	3 years 4 months 24 days
Incurred and expensed costs	$ 200,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Accounts receivable	12,000
Property and equipment	46,000
Goodwill	2,703,000
Deferred income tax liabilities, net	(1,074,000)
Total purchase price	(7,487,000)
Developed technology | Dextro, Inc.
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Developed technology	$ 5,800,000

Business Acquisitions - Breon E

Business Acquisitions - Breon Enterprises Acquisition (Details) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2018	Dec. 31, 2017
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill		$ 24,981	$ 14,927
Breon Enterprises
Business Acquisition [Line Items]
Total purchase price	$ 4,200
Increase (decrease) in accounts receivable	$ 2,200
Intangible assets, weighted average useful life	2 years 1 month 6 days
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill	$ 1,650
Total purchase price	4,150
TASER
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill		1,338	1,453
TASER | Breon Enterprises
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill	800
Software and Sensors
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill		$ 23,643	$ 13,474
Software and Sensors | Breon Enterprises
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill	800
Re-acquired distribution rights | Breon Enterprises
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Intangible assets other than goodwill acquired	2,100
Customer relationships | Breon Enterprises
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Intangible assets other than goodwill acquired	$ 400

Business Acquisitions - VIEVU,

Business Acquisitions - VIEVU, LLC. Acquisition (Details) - USD ($)	May 03, 2018	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill		$ 24,981,000	$ 24,981,000	$ 14,927,000
VIEVU
Business Acquisition [Line Items]
Cash consideration	$ 5,000,000
Net of cash acquired	100,000
Stock options transferred	$ 2,400,000
Shares transferred (in shares)	58,843
Contingent consideration	$ 6,000,000
Contingent consideration (in shares)	141,226
Contingent consideration, fair value	$ 5,800,000
Intangible assets, weighted average useful life			5 years 1 month 6 days
Revenue		6,700,000	$ 423,890,000	352,985,000
Direct costs incurred		16,900,000
(Loss) from operations			(27,035,000)	$ 2,145,000
Incurred and expensed costs		800,000	800,000
Expenses subsequent to acquisition date			1,200,000
Tax deductible goodwill		5,200,000	5,200,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Accounts receivable	1,776,000
Inventory	2,626,000
Property and equipment	362,000
Property and equipment	459,000
Contract assets	1,472,000
Developed technology	4,510,000
Goodwill	10,285,000
Accounts payable and accrued liabilities	(3,345,000)
Deferred revenue	(543,000)
Total purchase price	$ 17,602,000
Supply Agreement | VIEVU
Business Acquisition [Line Items]
Fair value of intangibles		$ 4,500,000	$ 4,500,000

Business Acquisitions - Unaudit

Business Acquisitions - Unaudited Pro Forma Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	8 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Basic (in dollars per share)		$ 0.49	$ (0.04)
Diluted (in dollars per share)		$ 0.47	$ (0.04)
VIEVU
Business Acquisition [Line Items]
Net sales	$ 6,700	$ 423,890	$ 352,985
Net income (loss)		$ 27,035	$ (2,145)

Segment Data - Additional Infor

Segment Data - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018segment
Segment Reporting [Abstract]
Number of reportable segments of company	2

Segment Data - Summary of Opera

Segment Data - Summary of Operational Information Relative to the Company's Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net sales	$ 114,791	$ 104,836	$ 99,226	$ 101,215	$ 94,651	$ 90,262	$ 79,643	$ 79,242	$ 420,068	$ 343,798	$ 268,245
Cost of sales									161,485	136,710	97,709
Gross margin	$ 65,346	$ 65,633	$ 63,143	$ 64,461	$ 63,016	$ 49,765	$ 45,637	$ 48,670	258,583	207,088	170,536
Sales, general and administrative									156,886	138,692	108,076
Research and development									76,856	55,373	30,609
Income from operations									24,841	13,023	31,851
Purchase of property and equipment									11,139	10,419	4,957
Purchase of intangible assets									558	1,024	3,495
Depreciation and amortization									10,615	8,041	3,658
TASER
Segment Reporting Information [Line Items]
Net sales									253,115	234,512	202,644
Cost of sales									80,354	72,054	61,930
Gross margin									172,761	162,458	140,714
Sales, general and administrative									90,910	78,202	63,617
Research and development									17,012	8,377	5,887
Income from operations									64,839	75,879	71,210
Software and Sensors
Segment Reporting Information [Line Items]
Net sales									166,953	109,286	65,601
Cost of sales									81,131	64,656	35,779
Gross margin									85,822	44,630	29,822
Sales, general and administrative									65,976	60,490	44,459
Research and development									59,844	46,996	24,722
Income from operations									(39,998)	(62,856)	(39,359)
Product
Segment Reporting Information [Line Items]
Net sales									327,635	285,859	238,573
Cost of sales									139,337	117,997	91,536
Product | TASER
Segment Reporting Information [Line Items]
Net sales									253,115	234,512	202,644
Cost of sales									80,354	72,054	61,930
Product | Software and Sensors
Segment Reporting Information [Line Items]
Net sales									74,520	51,347	35,929
Cost of sales									58,983	45,943	29,606
Service
Segment Reporting Information [Line Items]
Net sales									92,433	57,939	29,672
Cost of sales									22,148	18,713	6,173
Service | TASER
Segment Reporting Information [Line Items]
Net sales									0	0	0
Cost of sales									0	0	0
Service | Software and Sensors
Segment Reporting Information [Line Items]
Net sales									92,433	57,939	29,672
Cost of sales									$ 22,148	$ 18,713	$ 6,173

Selected Quarterly Financial _3

Selected Quarterly Financial Data (unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total out of period adjustments									$ 1,800
Net sales	$ 114,791	$ 104,836	$ 99,226	$ 101,215	$ 94,651	$ 90,262	$ 79,643	$ 79,242	420,068	$ 343,798	$ 268,245
Gross margin	65,346	65,633	63,143	64,461	63,016	49,765	45,637	48,670	258,583	207,088	170,536
Net income	$ 2,083	$ 5,711	$ 8,485	$ 12,926	$ (2,071)	$ 422	$ 2,276	$ 4,580	$ 29,205	$ 5,207	$ 17,297
Earnings per share
Basic (in dollars per share)	$ 0.04	$ 0.10	$ 0.15	$ 0.24	$ (0.04)	$ 0.01	$ 0.04	$ 0.09	$ 0.52	$ 0.10	$ 0.33
Diluted (in dollars per share)	$ 0.03	$ 0.10	$ 0.15	$ 0.24	$ (0.04)	$ 0.01	$ 0.04	$ 0.09	$ 0.50	$ 0.10	$ 0.32
Decrease to net sales									$ 900
Increase sales, general and administration expense									$ 1,300
Decrease to provision income taxes	$ 400

Supplemental Disclosure to Ca_3

Supplemental Disclosure to Cash Flows - Summary of Supplemental Non-Cash and Other Cash Flow Information (Detail) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 349,462	$ 75,105	$ 40,651
Restricted Cash	1,565	3,333	3,317
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	351,027	78,438	43,968	$ 59,526
Cash paid for income taxes, net of refunds	10,609	11,487	14,048
Non-cash transactions:
Contingent consideration related to business combinations	0	1,007	3,325
Property and equipment purchases in accounts payable	$ 501	$ 133	$ 82
Non-cash purchase consideration related to business combinations	12,508	0	0
Purchase of assets under capital lease obligations	$ 0	$ 0	$ 134

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts (Detail) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement in Valuation Allowances and Reserves
Balance at Beginning of Period	$ 729	$ 443	$ 322
Charged to Costs and Expenses	1,189	592	205
Charged to Other Accounts	0	0	0
Deductions	(36)	(306)	(84)
Balance at End of Period	$ 1,882	$ 729	$ 443