National Instruments (NATI) 10-Q 1 May 19 2019 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 25, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	NATIONAL INSTRUMENTS CORP /DE/
Entity Central Index Key	0000935494
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		131,866,173

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 228,766	$ 259,386
Short-term investments	251,297	271,396
Accounts receivable, net	215,012	242,955
Inventories, net	204,710	194,146
Prepaid expenses and other current assets	66,434	54,337
Total current assets	966,219	1,022,220
Property and equipment, net	228,164	245,201
Goodwill	262,384	264,530
Intangible assets, net	104,066	110,783
Operating lease right-of-use assets	70,861	0
Other long-term assets	39,644	28,501
Total assets	1,671,338	1,671,235
Current liabilities:
Accounts payable and accrued liabilities	50,576	48,388
Accrued compensation	35,148	45,821
Deferred revenue - current	130,336	127,288
Operating lease liabilities - current	16,088	0
Other current liabilities	27,807	25,913
Other taxes payable	28,001	35,574
Total current liabilities	287,956	282,984
Deferred income taxes	24,268	25,457
Liability for uncertain income tax positions	8,025	9,775
Income taxes payable - non-current	74,546	74,546
Deferred revenue - non-current	32,393	32,636
Operating lease liabilities - non-current	38,154	0
Other long-term liabilities	4,743	7,479
Total liabilities	470,085	432,877
Commitments and contingencies
Stockholders' equity:
Preferred stock: par value $0.01; 5,000,000 shares authorized; none issued and outstanding	0	0
Common stock: par value $0.01; 360,000,000 shares authorized; 131,866,173 shares and 132,655,941 shares issued and outstanding, respectively	1,319	1,327
Additional paid-in capital	910,602	897,544
Retained earnings	307,153	356,418
Accumulated other comprehensive loss	(17,821)	(16,931)
Total stockholders’ equity	1,201,253	1,238,358
Total liabilities and stockholders’ equity	$ 1,671,338	$ 1,671,235

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value per share (in usd per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value per share (in usd per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	360,000,000	360,000,000
Common stock, issued (in shares)	131,866,173	132,655,941
Common stock, outstanding (in shares)	131,866,173	132,655,941

Consolidated Statements Of Inco

Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net sales:
Total net sales	$ 311,074	$ 311,897
Cost of sales:
Total cost of sales	76,075	74,523
Gross profit	234,999	237,374
Operating expenses:
Sales and marketing	117,551	120,117
Research and development	66,166	61,843
General and administrative	27,883	27,277
Total operating expenses	211,600	209,237
Operating income	23,399	28,137
Other income:
Interest income	2,234	1,015
Net foreign exchange gain	366	979
Other loss, net	(24)	(519)
Income before income taxes	25,975	29,612
Provision for income taxes	2,755	5,344
Net income	$ 23,220	$ 24,268
Basic earnings per share (in dollars per share)	$ 0.18	$ 0.19
Weighted average shares outstanding - basic	132,252	131,127
Diluted earnings per share (in dollars per share)	$ 0.17	$ 0.18
Weighted average shares outstanding - diluted	133,367	132,624
Dividends declared per share (in dollars per share)	$ 0.25	$ 0.23
Product
Net sales:
Total net sales	$ 277,702	$ 280,359
Cost of sales:
Total cost of sales	74,188	72,317
Software maintenance
Net sales:
Total net sales	33,372	31,538
Cost of sales:
Total cost of sales	$ 1,887	$ 2,206

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 23,220	$ 24,268
Other comprehensive income, before tax and net of reclassification adjustments:
Foreign currency translation adjustment	(3,067)	5,804
Unrealized gain (loss) on securities available-for-sale	1,175	(696)
Unrealized gain (loss) on derivative instruments	1,212
Unrealized gain (loss) on derivative instruments		(3,771)
Other comprehensive (loss) gain, before tax	(680)	1,337
Tax benefit (expense) related to items of other comprehensive income	210	(872)
Other comprehensive (loss) gain, net of tax	(890)	2,209
Comprehensive income	$ 22,330	$ 26,477

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flow from operating activities:
Net income	$ 23,220	$ 24,268
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	18,012	17,436
Stock-based compensation	11,034	8,204
Tax expense from deferred income taxes	(1,650)	(2,046)
Changes in operating assets and liabilities	(8,469)	(7,879)
Net cash provided by operating activities	42,147	39,983
Cash flow from investing activities:
Capital expenditures	(10,936)	(8,115)
Capitalization of internally developed software	(2,279)	(7,668)
Additions to other intangibles	(106)	(2,855)
Payments to acquire equity-method investment	(9,784)	0
Purchases of short-term investments	(60,094)	(52,355)
Sales and maturities of short-term investments	81,151	10,211
Net cash used in investing activities	(2,048)	(60,782)
Cash flow from financing activities:
Proceeds from issuance of common stock	9,213	8,600
Repurchase of common stock	(46,404)	0
Dividends paid	(33,110)	(30,177)
Net cash used in financing activities	(70,301)	(21,577)
Effect of exchange rate changes on cash	(418)	2,577
Net change in cash and cash equivalents	(30,620)	(39,799)
Cash and cash equivalents at beginning of period	259,386	290,164
Cash and cash equivalents at end of period	$ 228,766	$ 250,365

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Additional-Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income/(Loss)
Beginning balance (in shares) at Dec. 31, 2017			130,978,947
Beginning balance at Dec. 31, 2017		$ 1,128,021	$ 1,310	$ 829,979	$ 313,241	$ (16,509)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		24,268			24,268
Other comprehensive income, net of tax		2,209				2,209
Issuance of common stock under employee plans, including tax benefits (in shares)			225,848
Issuance of common stock under employee plans, including tax benefits		8,600	$ 2	8,598
Stock-based compensation		8,166		8,166
Dividends paid	[1]	(30,177)
Ending balance (in shares) at Mar. 31, 2018			131,204,795
Ending Balance at Mar. 31, 2018		$ 1,149,706	$ 1,312	846,743	315,951	(14,300)
Beginning balance (in shares) at Dec. 31, 2018		132,655,941	132,655,941
Beginning balance at Dec. 31, 2018		$ 1,238,358	$ 1,327	897,544	356,418	(16,931)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		23,220			23,220
Other comprehensive income, net of tax		(890)				(890)
Issuance of common stock under employee plans, including tax benefits (in shares)			245,330
Issuance of common stock under employee plans, including tax benefits		9,213	$ 2	9,211
Stock-based compensation		10,866		10,866
Repurchase of common stock (in shares)			1,035,098
Repurchase of common stock		(46,404)	$ (10)	(7,019)	(39,375)
Dividends paid	[1]	$ (33,110)			(33,110)
Ending balance (in shares) at Mar. 31, 2019		131,866,173	131,866,173
Ending Balance at Mar. 31, 2019		$ 1,201,253	$ 1,319	$ 910,602	$ 307,153	$ (17,821)
[1]	Cash dividends declared per share of common stock were $0.25 and $0.23 for the three month periods ended March 31, 2019 and 2018, respectively.

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (in dollars per share)	$ 0.25	$ 0.23

Basis of presentation

Basis of presentation	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	Basis of presentation The accompanying unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto for the year ended December 31, 2018 , included in our annual report on Form 10-K, filed with the Securities and Exchange Commission. In our opinion, the accompanying consolidated financial statements reflect all adjustments (consisting only of normal recurring items) considered necessary to present fairly our financial position at March 31, 2019 and December 31, 2018 , the results of our operations and comprehensive income for the three months ended March 31, 2019 and 2018 , and the cash flows for the three months ended March 31, 2019 and 2018 . Our operating results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 . These financial statements have been prepared in accordance with accounting principles generally accepted in the United States. Recently Adopted Accounting Pronouncements Leases In February 2016, the Financial Accounting Standards Board ("FASB") established Topic 842, Leases, by issuing Accounting Standards Update (ASU) No. 2016-02, which supersedes ASC 840, Leases, and requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. Topic 842, as amended, (the "new lease standard") establishes a right-of-use model (ROU) that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. We adopted the new lease standard on January 1, 2019 and used the effective date as our date of initial adoption. Consequently, financial information will not be updated and the disclosures required under the new standard will not be provided for earlier periods. We have completed a qualitative and quantitative assessment of our lease portfolio, in which the standard had a material impact on our consolidated balance sheet but did not have an impact on our consolidated income statement. Upon adoption, we recognized lease liabilities of approximately $52 million , with corresponding ROU assets of the same amount, based on the present value of the remaining minimum rental payments under current leasing standards for our existing operating leases. Additionally, we also reclassified approximately $ 19 million from "Property, plant and equipment, net" to "Operating lease right-of-use assets" related to prepaid leasehold land. The new standard provides a number of optional practical expedients in transition. We elected the 'package of practical expedients', which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs. We did not elect the use-of-hindsight or the practical expedient pertaining to land easements; the latter not being applicable to us. The new standard also provides practical expedients for an entity's ongoing accounting. We elected the short-term lease recognition exemption for all leases that qualify. This means, for those leases that qualify, we will not recognize ROU assets or lease liabilities, and this includes not recognizing ROU assets or lease liabilities for existing short-term leases of those assets in transition. We also elected the practical expedient to not separate lease and non-lease components for our office leases. The cumulative effects of the changes made to our consolidated January 1, 2019 balance sheet for the adoption of the new lease standard were as follows (in thousands): Balance at December 31, 2018 Adjustments Due to ASU 2016-02 Balance at January 1, 2019 Assets Property, plant and equipment, net $ 245,201 $ (18,606 ) $ 226,595 Operating lease right-of-use assets — 68,938 68,938 Liabilities and Stockholders' Equity Operating lease liabilities, current — 18,597 18,597 Operating lease liabilities, non-current — $ 33,853 $ 33,853 Other current liabilities $ 25,913 $ (2,118 ) $ 23,795 Other Recently Adopted Accounting Pronouncements In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . The ASU expands strategies that qualify for hedge accounting, changes how many hedging relationships are presented in the financial statements, and simplifies the application of hedge accounting in certain situations. On January 1, 2019, we adopted the guidance in ASU 2017-12. Adoption did not have a material impact on our financial statements. We continue to assess opportunities enabled by the new standard to expand our risk management strategies. In August 2018, the Securities and Exchange Commission ("SEC") issued Release No. 33-10532 that amends and clarifies certain financial reporting requirements. The principal change to our financial reporting will be the inclusion of the annual disclosure requirement of changes in stockholders’ equity in Rule 3-04 of Regulation S-X to interim periods. We adopted this new rule beginning with our financial reporting for the quarter ended March 31, 2019. In January 2018, the FASB issued ASU 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which gives entities the option to reclassify to retained earnings tax effects resulting from the Tax Cuts and Jobs Act (the "Act") related to items that the FASB refers to as having been stranded in accumulated other comprehensive income ("OCI"). We adopted ASU 2018-02 effective January 1, 2019, and we did not elect the option to reclassify to retained earnings the tax effects resulting from the Act that are stranded in accumulated OCI. The adoption of the new guidance did not have a material effect on our consolidated financial statements. Recent Accounting Guidance Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The ASU will replace the incurred loss impairment methodology under current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. We will be required to use a forward-looking expected credit loss model for accounts receivables and other financial instruments. This ASU requires instruments measured at amortized cost to be presented at the net amount expected to be collected. Entities are also required to record allowances for available-for-sale debt securities rather than reduce the carrying amount. We do not plan to adopt the ASU earlier than our required effective date of January 1, 2020. We expect that the adoption of the ASU will not have a material impact on our financial statements. Summary of Significant Accounting Policies As discussed above, we adopted the new lease standard as of January 1, 2019. The impact of this new guidance on our accounting policies and financial statements is described below. Additionally, in the first quarter of 2019, we granted performance-based restricted stock units to certain executives under our 2015 Equity Incentive Plan ("PRSUs"). The PRSU awards granted during the three months ended March 31, 2019 include a market condition as defined by ASC 718. The impact of the new equity awards on our accounting policies is described below. There were no other significant changes in our accounting policies during the three months ended March 31, 2019 compared to the significant accounting policies described in our Annual Report on Form 10-K for the year ended December 31, 2018. Stock-Based Compensation Stock-based compensation costs are based on the fair value on the date of grant for all restricted stock units ("RSUs") and on the date of enrollment for the employee stock purchase plan. We recognize compensation expense ratably over the requisite service period of the awards. PRSUs are restricted stock unit awards that vest based on a market condition, currently our stockholder return relative to the total stockholder return of the constituents of the Russell 2000 Index at the end of a three-year performance period. Up to 200% of the full target number of shares subject to each PRSU award are eligible to be earned after the completion of the three-year performance period based on our total stockholder return relative to the total stockholder return of the Russell 2000 Index at the end of the performance period. The fair values of RSUs are estimated using their market price on the date of grant. The fair values of employee stock purchase plans are estimated using the Black-Scholes option-pricing model. The fair values of PRSUs are estimated using a Monte Carlo simulation. The determination of fair value of the PRSUs is affected by our stock price and a number of assumptions including the expected volatility, expected dividend yield and the risk-free interest rate. Our expected volatility at the date of grant was based on the historical volatilities of our stock and the constituents of the Russell 2000 Index over the performance period. Refer to Note 11 – Authorized shares of common and preferred stock and stock-based compensation plans for additional information on our equity-based compensation programs. Leases We determine whether an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use ("ROU") assets and operating lease liabilities (current and non-current) on our consolidated balance sheet. Finance leases are included in property and equipment, other current liabilities, and other long-term liabilities in our consolidated balance sheet. Operating lease ROU assets and operating lease liabilities are recognized based on their present value of the future minimum lease payments over the lease term at commencement date. As none of our leases provide an implicit rate we use our incremental borrowing rate based on the information available as of the commencement date. The operating lease ROU assets also includes any lease payments made and excludes lease incentives and initial direct costs incurred. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components. For office leases we account for the lease and non-lease components as a single lease component. For certain leases, such as equipment and vehicles, we account for the lease and non-lease components separately. Additionally, for certain equipment leases, we apply a portfolio approach to effectively account for the operating lease ROU assets and liabilities. Refer to Note 8 - Leases for additional information on our leasing activities. Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income by the weighted average number of common shares outstanding during each period. Diluted EPS is computed by dividing net income by the weighted average number of common shares and common share equivalents outstanding (if dilutive) during each period. The number of common share equivalents, which includes RSUs, is computed using the treasury stock method. The reconciliation of the denominators used to calculate basic EPS and diluted EPS for the three months ended March 31, 2019 and 2018 , are as follows:  Three Months Ended March 31,  (In thousands)  (Unaudited)  2019 2018 Weighted average shares outstanding-basic 132,252 131,127 Plus: Common share equivalents RSUs 1,115 1,497 Weighted average shares outstanding-diluted 133,367 132,624 Stock awards to acquire 67,100 shares and 0 shares for the three months ended March 31, 2019 and 2018 , respectively, were excluded in the computations of diluted EPS because the effect of including the stock awards would have been anti-dilutive.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Revenue Recognition Revenue is recognized upon transfer of control of the 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 our products or services, which are generally capable of being distinct and accounted for as separate performance obligations. Revenue is recognized net of allowances for returns and any taxes collected from customers, which are subsequently remitted to governmental authorities. Disaggregation of Revenues We disaggregate revenue from contracts with customers based on the timing of transfer of goods or services to customers (point-in-time or over time) and geographic region based on the billing location of the customer. The geographic regions that are tracked are the Americas (United States, Canada, and Latin America), EMEIA (Europe, Middle East, India, and Africa) and APAC (Australia, New Zealand, Southeast Asia, China, South Korea and Japan). We operate as one operating segment. Total net sales based on the disaggregation criteria described above are as follows:  Three Months Ended March 31, (In thousands) (Unaudited)  2019 2018 Net sales: Point-in-Time (1) Over Time Total Point-in-Time (1) Over Time Total Americas $ 99,681 22,974 $ 122,655 $ 100,053 19,669 $ 119,722 EMEIA 79,122 19,685 98,807 86,907 18,505 105,412 APAC 81,450 8,162 89,612 78,685 8,078 86,763 Total net sales (1) $ 260,253 50,821 $ 311,074 $ 265,645 46,252 $ 311,897 (1): Net sales contains hedging gains and losses, which do not represent revenues recognized from customers. See Note - 5 Derivatives instruments and hedging activities for more information on the impact of our hedging activities on our results of operations Information about Contract Balances Amounts collected in advance of services being provided are accounted for as deferred revenue. Nearly all of our deferred revenue balance is related to extended hardware and software maintenance contracts. Payment terms and conditions vary by contract type, although payment is typically due within 30 to 90 days of contract inception. In instances where the timing of revenue recognition differs from the timing of invoicing, we have determined our contracts generally do not include a significant financing component. The primary purpose of our invoicing terms is to provide customers with simplified and predictable ways of purchasing our products and services, not to receive financing from our customers, such as invoicing at the beginning of a subscription term with a portion of the revenue recognized ratably over the contract period, or to provide customers with financing, such as multi-year on-premises licenses that are invoiced annually with revenue recognized upfront. Changes in deferred revenue, current and non-current, during the three months ended March 31, 2019 were as follows: Amount  (In thousands) Deferred Revenue at December 31, 2018 $ 159,924 Deferral of revenue billed in current period, net of recognition 51,562 Recognition of revenue deferred in prior periods (47,995 ) Foreign currency translation impact (762 ) Balance as of March 31, 2019 (unaudited) $ 162,729 For the three months ended March 31, 2019, revenue recognized from performance obligations related to prior periods (for example, due to changes in transaction price) was not material. Amounts recognized as revenue in excess of amounts billed are recorded as unbilled receivables. Unbilled receivables which are anticipated to be invoiced in the next twelve months are included in "accounts receivable, net" on the consolidated balance sheet. Based on the nature of our contracts with customers, we do not typically recognize unbilled receivables related to revenues recognized in excess of amounts billed. For the three months ended March 31, 2019, amounts recognized related to unbilled receivables were not material. Unsatisfied Performance Obligations Revenue expected to be recognized in any future period related to remaining performance obligations, excluding revenue pertaining to contracts that have an original expected duration of one year or less, and contracts where revenue is recognized as invoiced, was approximately $57 million as of March 31, 2019. Since we typically invoice customers at contract inception, this amount is included in our current and non-current deferred revenue balances. As of March 31, 2019, we expect to recognize approximately 37% of the revenue related to these unsatisfied performance obligations during the remainder of 2019, 35% during 2020, and 28% thereafter. Assets Recognized from the Costs to Obtain a Contract with a Customer We recognize an asset for the incremental costs of obtaining a contract with a customer if we expect the benefit of those costs to be longer than one year. We have determined that certain sales incentive programs meet the requirements to be capitalized. Capitalized incremental costs related to initial contracts and renewals are amortized over the same period because the commissions paid on both the initial contract and renewals are commensurate with one another. Total capitalized costs to obtain a contract were immaterial during the periods presented and are included in other long-term assets on our consolidated balance sheets.

Short-term investments

Short-term investments	3 Months Ended
	Mar. 31, 2019
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Short-term investments	Short-term investments The following tables summarize unrealized gains and losses related to our short-term investments designated as available-for-sale debt securities:  As of March 31, 2019 (In thousands) (Unaudited)  Gross Gross  Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Corporate bonds $ 203,851 $ 915 $ (347 ) $ 204,419 U.S. treasuries and agencies 46,852 27 (1 ) 46,878 Total Short-term investments $ 250,703 $ 942 $ (348 ) $ 251,297 (In thousands) As of December 31, 2018  Gross Gross  Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Corporate bonds $ 235,045 $ 726 $ (1,298 ) $ 234,473 U.S. treasuries and agencies 36,932 2 (11 ) 36,923 Total Short-term investments $ 271,977 $ 728 $ (1,309 ) $ 271,396 The following tables summarize the contractual maturities of our short-term investments designated as available-for-sale debt securities:  As of March 31, 2019 (In thousands) (Unaudited)  Adjusted Cost Fair Value Due in less than 1 year $ 132,980 $ 133,008 Due in 1 to 5 years 117,723 118,289 Total available-for-sale debt securities $ 250,703 $ 251,297  Due in less than 1 year Adjusted Cost Fair Value Corporate bonds $ 86,128 $ 86,130 U.S. treasuries and agencies 46,852 46,878 Total available-for-sale debt securities $ 132,980 $ 133,008  Due in 1 to 5 years Adjusted Cost Fair Value Corporate bonds $ 117,723 $ 118,289 Total available-for-sale debt securities $ 117,723 $ 118,289 Equity-Method Investments The carrying value of our equity method investments was $13 million as of March 31, 2019. Our proportionate share of the income from equity-method investments was not material for the periods presented.

Fair value measurements

Fair value measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements We define fair value to be the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, we consider the principal or most advantageous market that market participants may use when pricing the asset or liability. We follow a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. Fair value measurement is determined based on the lowest level input that is significant to the fair value measurement. The three values of the fair value hierarchy are the following: Level 1 – Quoted prices in active markets for identical assets or liabilities Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly Level 3 – Inputs that are not based on observable market data Assets and liabilities measured at fair value on a recurring basis are summarized below:  Fair Value Measurements at Reporting Date Using (In thousands) (Unaudited) Description March 31, 2019 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash and cash equivalents available for sale: Money Market Funds $ 57,584 $ 57,584 $ — $ — Short-term investments available for sale: Corporate bonds 204,419 — 204,419 — U.S. treasuries and agencies 46,878 — 46,878 — Derivatives 10,753 — 10,753 Total Assets $ 319,634 $ 57,584 $ 262,050 $ —  Liabilities Derivatives $ (1,461 ) $ — $ (1,461 ) $ — Total Liabilities $ (1,461 ) $ — $ (1,461 ) $ — (In thousands) Fair Value Measurements at Reporting Date Using Description December 31, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash and cash equivalents available for sale: Money Market Funds $ 62,094 $ 62,094 $ — $ — Corporate notes and bonds 9,979 — 9,979 — Short-term investments available for sale: Corporate bonds 234,473 — 234,473 — Time deposits 36,923 — 36,923 — Derivatives 9,369 — 9,369 — Total Assets $ 352,838 $ 62,094 $ 290,744 $ —  Liabilities Derivatives $ (1,483 ) $ — $ (1,483 ) $ — Total Liabilities $ (1,483 ) $ — $ (1,483 ) $ — We value our available-for-sale short-term investments based on pricing from third party pricing vendors, who may use quoted prices in active markets for identical assets (Level 1 inputs) or inputs other than quoted prices that are observable either directly or indirectly (Level 2 inputs) in determining fair value. We classify all of our fixed income available-for-sale securities as having Level 2 inputs. The valuation techniques used to measure the fair value of our financial instruments having Level 2 inputs were derived from non-binding market consensus prices that are corroborated by observable market data, quoted market prices for similar instruments, or pricing models, such as discounted cash flow techniques. We believe all of these sources reflect the credit risk associated with each of our available-for-sale short-term investments. Short-term investments available-for-sale consists of debt securities issued by states of the U.S. and political subdivisions of the U.S., corporate debt securities and debt securities issued by U.S. government organizations and agencies. All of our short-term investments available-for-sale have contractual maturities of less than 60 months . Our derivatives consist of foreign currency forward contracts. Our foreign currency forward contracts are valued using an income approach (Level 2) based on the spot rate less the contract rate multiplied by the notional amount. We consider counterparty credit risk in the valuation of our derivatives. However, counterparty credit risk did not impact the valuation of our derivatives during the three months ended March 31, 2019 . There were no transfers in or out of Level 1 or Level 2 during the three months ended March 31, 2019 . As of March 31, 2019 , our short-term investments did not include sovereign debt from any country other than the United States. We did not have any items that were measured at fair value on a nonrecurring basis at March 31, 2019 and December 31, 2018 . The carrying value of net accounts receivable, accounts payable, and long-term debt contained in the consolidated balance sheets approximates fair value.

Derivative instruments and hedg

Derivative instruments and hedging activities	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative instruments and hedging activities	Derivative instruments and hedging activities We recognize all of our derivative instruments as either assets or liabilities in our statement of financial position at fair value. The accounting for changes in the fair value (i.e., gains or losses) of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and further, on the type of hedging relationship. For those derivative instruments that are designated and qualify as hedging instruments, we designate the hedging instrument, based upon the exposure being hedged, as a fair value hedge, cash flow hedge, or a hedge of a net investment in a foreign operation. We have operations in over 50 countries. Sales outside of the Americas accounted for approximately 61% and 62% of our net sales during the three months ended March 31, 2019 and 2018 , respectively. Our activities expose us to a variety of market risks, including the effects of changes in foreign currency exchange rates. These financial risks are monitored and managed by us as an integral part of our overall risk management program. We maintain a foreign currency risk management strategy that uses derivative instruments (foreign currency forward contracts) to help protect our earnings and cash flows from fluctuations caused by the volatility in currency exchange rates. Movements in foreign currency exchange rates pose a risk to our operations and competitive position, in that exchange rate changes may affect our profitability and cash flow, and the business or pricing strategies of our non-U.S. based competitors. The vast majority of our foreign sales are denominated in the customers’ local currency. We purchase foreign currency forward contracts as hedges of forecasted sales that are denominated in foreign currencies and as hedges of foreign currency denominated financial assets or liabilities. These contracts are entered into to help protect against the risk that the eventual dollar-net-cash inflows resulting from such sales or firm commitments will be adversely affected by changes in exchange rates. We also purchase foreign currency forward contracts as hedges of forecasted expenses that are denominated in foreign currencies. These contracts are entered into to help protect against the risk that the eventual dollar-net-cash outflows resulting from foreign currency operating and cost of sales expenses will be adversely affected by changes in exchange rates. We designate foreign currency forward contracts as cash flow hedges of forecasted net sales or forecasted expenses. In addition, we hedge our foreign currency denominated balance sheet exposures using foreign currency forward contracts that are not designated as hedging instruments. None of our derivative instruments contain a credit-risk-related contingent feature. Cash flow hedges To help protect against the reduction in value caused by a fluctuation in foreign currency exchange rates of forecasted foreign currency cash flows resulting from international sales over the next one to three years, we have instituted a foreign currency cash flow hedging program. We hedge portions of our forecasted net sales and forecasted expenses denominated in foreign currencies with forward contracts. For forward contracts, when the dollar strengthens significantly against the foreign currencies, the change in the present value of future foreign currency cash flows may be offset by the change in the fair value of the forward contracts designated as hedges. We purchase foreign currency forward contracts for up to 100% of our forecasted exposures in selected currencies (primarily in Euro, Japanese yen, Hungarian forint, British pound, Malaysian ringgit, Chinese yuan, and Korean won) and limit the duration of these contracts to 36 months or less. For derivative instruments that are designated and qualify as a cash flow hedge, the gain or loss on the derivative is reported as a component of accumulated OCI and reclassified into earnings in the same line item (net sales, operating expenses, or cost of sales) associated with the forecasted transaction and in the same period or periods during which the hedged transaction affects earnings. Hedge effectiveness of foreign currency forwards designated as cash flow hedges are measured by comparing the hedging instrument’s cumulative change in fair value from inception to maturity to the forecasted transaction’s terminal value. We held forward contracts designated as cash flow hedges with the following notional amounts: (In thousands) US Dollar Equivalent  As of March 31, 2019 As of December 31,  (Unaudited) 2018 Chinese yuan 79,931 $ 45,520 Euro 141,484 134,654 Japanese yen 22,543 15,141 Hungarian forint 32,192 35,384 British pound 8,892 9,948 Malaysian ringgit 25,245 27,778 Korean won 13,608 8,331 Total forward contracts notional amount $ 323,895 $ 276,756 The contracts in the foregoing table had contractual maturities of 21 months or less and 24 months or less at March 31, 2019 and December 31, 2018 , respectively. At March 31, 2019 , we expect to reclassify $7.3 million of gains on derivative instruments from accumulated OCI to net sales during the next twelve months when the hedged international sales occur, $(0.1) million of losses on derivative instruments from accumulated OCI to cost of sales during the next twelve months when the cost of sales are incurred and $(0.1) million of losses on derivative instruments from accumulated OCI to operating expenses during the next twelve months when the hedged operating expenses occur. Expected amounts are based on derivative valuations at March 31, 2019 . Actual results may vary materially as a result of changes in the corresponding exchange rates subsequent to this date. Other Derivatives Other derivatives not designated as hedging instruments consist primarily of foreign currency forward contracts that we use to hedge our foreign denominated net receivable or net payable positions to help protect against the change in value caused by a fluctuation in foreign currency exchange rates. We typically attempt to hedge up to 90% of our outstanding foreign denominated net receivables or net payables and typically limit the duration of these foreign currency forward contracts to approximately 90 days or less. The gain or loss on the derivatives as well as the offsetting gain or loss on the hedge item attributable to the hedged risk is recognized in current earnings under the line item “net foreign exchange gain (loss).” As of March 31, 2019 and December 31, 2018 , we held foreign currency forward contracts that were not designated as hedging instruments with a notional amount of $42 million and $71 million , respectively. The following tables present the fair value of derivative instruments on our Consolidated Balance Sheets at March 31, 2019 and December 31, 2018 , respectively.  Asset Derivatives  March 31, 2019 December 31, 2018 (In thousands) (Unaudited)   Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments Foreign exchange contracts - ST forwards Prepaid expenses and other current assets $ 7,811 Prepaid expenses and other current assets $ 7,594 Foreign exchange contracts - LT forwards Other long-term assets 2,487 Other long-term assets 1,380 Total derivatives designated as hedging instruments $ 10,298 $ 8,974 Derivatives not designated as hedging instruments Foreign exchange contracts - ST forwards Prepaid expenses and other current assets $ 455 Prepaid expenses and other current assets $ 395 Total derivatives not designated as hedging instruments $ 455 $ 395 Total derivatives $ 10,753 $ 9,369  Liability Derivatives  March 31, 2019 December 31, 2018 (In thousands) (Unaudited)  Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments Foreign exchange contracts - ST forwards Other current liabilities $ (763 ) Other current liabilities $ (662 )  Foreign exchange contracts - LT forwards Other long-term liabilities (225 ) Other long-term liabilities (191 ) Total derivatives designated as hedging instruments $ (988 ) $ (853 )  Derivatives not designated as hedging instruments  Foreign exchange contracts - ST forwards Other current liabilities $ (473 ) Other current liabilities $ (630 ) Total derivatives not designated as hedging instruments $ (473 ) $ (630 )  Total derivatives $ (1,461 ) $ (1,483 ) The following tables present the effect of derivative instruments on our Consolidated Statements of Income for three month periods ended March 31, 2019 and 2018 , respectively: March 31, 2019 (In thousands) (Unaudited) Derivatives in Cash Flow Hedging Relationship Gain or (Loss) Recognized in OCI on Derivative Location of Gain or (Loss) Reclassified from Accumulated OCI into Income Gain or (Loss) Reclassified from Accumulated OCI into Income Foreign exchange contracts - forwards $ 1,800 Net sales $ 1,745  Foreign exchange contracts - forwards (270 ) Cost of sales 20  Foreign exchange contracts - forwards (318 ) Operating expenses 29 Total $ 1,212 $ 1,794 March 31, 2018 (In thousands) (Unaudited) Derivatives in Cash Flow Hedging Relationship Gain or (Loss) Recognized in OCI on Derivative Location of Gain or (Loss) Reclassified from Accumulated OCI into Income Gain or (Loss) Reclassified from Accumulated OCI into Income Foreign exchange contracts - forwards $ (5,073 ) Net sales $ (2,620 )  Foreign exchange contracts - forwards 726 Cost of sales 341  Foreign exchange contracts - forwards 576 Operating expenses 456 Total $ (3,771 ) $ (1,823 ) (In thousands) Derivatives not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income Amount of Gain (Loss) Recognized in Income Amount of Gain (Loss) Recognized in Income  March 31, 2019 March 31, 2018  (Unaudited) (Unaudited) Foreign exchange contracts - forwards Net foreign exchange gain/(loss) $ (228 ) (1,761 )  Total $ (228 ) $ (1,761 ) ໿

Inventories, net

Inventories, net	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Inventories, net	Inventories, net Inventories, net consist of the following:  March 31, 2019 December 31, (In thousands) (Unaudited) 2018  Raw materials $ 102,186 $ 98,346 Work-in-process 9,708 9,306 Finished goods 92,816 86,494  $ 204,710 $ 194,146 ໿

Intangible assets and goodwill

Intangible assets and goodwill	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets and goodwill	Intangible assets and goodwill Intangible assets at March 31, 2019 and December 31, 2018 are as follows:  March 31, 2019 (In thousands) (Unaudited) December 31, 2018  Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Capitalized software development costs $ 125,857 $ (55,785 ) $ 70,072 $ 123,842 $ (49,299 ) $ 74,543 Acquired technology 91,901 (85,502 ) 6,399 92,236 (84,962 ) 7,274 Patents 34,542 (22,213 ) 12,329 34,427 (21,725 ) 12,702 Other 46,214 (30,948 ) 15,266 46,437 (30,173 ) 16,264  $ 298,514 $ (194,448 ) $ 104,066 $ 296,942 $ (186,159 ) $ 110,783 Software development costs capitalized for the three month periods ended March 31, 2019 and 2018 were $2.4 million and $8.0 million , respectively, and related amortization expense was $6.9 million and $6.2 million , respectively. Capitalized software development costs for the three month periods ended March 31, 2019 and 2018 included costs related to stock based compensation of $0.1 million and $0.3 million , respectively. Amortization of capitalized software development costs is computed on an individual product basis for those products available for market and is recognized based on the product’s estimated economic life, generally three to six years. Acquired technology and other intangible assets are amortized over their useful lives, which range from three to eight years. Patents are amortized using the straight-line method over their estimated period of benefit, generally 10 to 17 years. Total intangible assets amortization expenses were $9.0 million and $8.4 million for the three month periods ended March 31, 2019 and 2018 , respectively. Goodwill The carrying amount of goodwill as of March 31, 2019 , was as follows:  Amount  (In thousands) Balance as of December 31, 2018 $ 264,530 Foreign currency translation impact (2,146 ) Balance as of March 31, 2019 (unaudited) $ 262,384 The excess purchase price over the fair value of assets acquired is recorded as goodwill. As we have one operating segment comprised of components with similar economic characteristics, we allocate goodwill to one reporting unit for goodwill impairment testing. Goodwill is tested for impairment on an annual basis, and between annual tests if indicators of potential impairment exist, using a fair-value-based approach based on the market capitalization of the reporting unit. Our annual impairment test is performed in the fourth quarter of each year. No impairment of goodwill was identified during the three months ended March 31, 2019 or the twelve months ended December 31, 2018 .

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases We have operating leases for corporate offices, automobiles, and certain equipment. Our leases have remaining terms of 1 year to 95 years, some of which may include options to extend the leases for up to 9 years, and some of which may include options to terminate the leases within 1 year. Leases with an initial term of 12 months or less are not recorded on the balance sheet; we recognize lease expense for these leases on a straight-line basis over the lease term. Amounts related to finance lease activities and income from leasing activities were not material for the periods presented. The components of operating lease expense were as follows (unaudited): (In thousands) March 31, 2019 Operating Lease Cost (a) $ 5,725 (a) includes variable and short-term lease costs Supplemental cash flow information related to operating leases were as follows (unaudited): (In thousands) March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases 4,791 Supplemental non-cash information: Operating lease right-of-use assets obtained in exchange for new operating lease obligations 6,334 Maturities of lease liabilities as of March 31, 2019 were as follows (unaudited): (In thousands) Years ending December 31, Operating Leases 2019 (Excluding the three months ended March 31, 2019) $ 15,280 2020 15,295 2021 10,512 2022 7,573 2023 6,669 Thereafter 14,936 Total future minimum lease payments 70,265 Less imputed interest (16,023 ) Total $ 54,242 Weighted Average Remaining Lease Term (years) Operating Leases 5.22 Weighted Average Discount Rate Operating Leases 6.0 % As of March 31, 2019, we have additional operating leases, that have not commenced during the period, which were not material.

Income taxes

Income taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income taxes	Income taxes We account for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the expected tax consequences of temporary differences between the tax bases of assets and liabilities and their reported amounts. Valuation allowances are established when necessary to reduce deferred tax assets to amounts which are more likely than not to be realized. We had a valuation allowance of $80 million at March 31, 2019 and December 31, 2018 . A majority of the valuation allowance is related to the deferred tax assets of National Instruments Hungary Kft. (“NI Hungary”). We account for uncertainty in income taxes recognized in our financial statements using prescribed recognition thresholds and measurement attributes for financial statement disclosure of tax positions taken or expected to be taken on our tax returns. We had $8.0 million and $9.8 million of unrecognized tax benefits at March 31, 2019 and December 31, 2018 , respectively, all of which would affect our effective income tax rate if recognized. We recorded a gross increase in unrecognized tax benefits of $0.2 million for the three month period ended March 31, 2019 , as a result of the tax positions taken during this period. We recorded a gross decrease in unrecognized tax benefits of $2.0 million for the three month period ended March 31, 2019 as a result of closing of open tax years. As of March 31, 2019 , it is reasonably possible that we will recognize tax benefits in the amount of $1.5 million in the next twelve months due to the closing of open tax years. The nature of the uncertainty is related to deductions taken on returns that have not been examined by the applicable tax authority. Our continuing policy is to recognize interest and penalties related to income tax matters in income tax expense. As of March 31, 2019 , we had approximately $0.7 million accrued for interest related to uncertain tax positions. The tax years 2012 through 2019 remain open to examination by the major taxing jurisdictions to which we are subject. Our provision for income taxes reflected an effective tax rate of 11% and 18% for the three month period ended March 31, 2019 and 2018 , respectively. For the three month period ended March 31, 2019 , our effective tax rate was lower than the U.S. federal statutory rate of 21% as a result of an enhanced deduction for certain research and development expenses, profits in foreign jurisdictions with reduced income tax rates, the deduction for foreign-derived deduction eligible income, a decrease in unrecognized tax benefits resulting from the closing of open tax years, the research and development tax credit, and a tax benefit from disqualifying dispositions of equity awards that do not ordinarily result in a tax benefit, offset by the U.S. tax on global intangible low-taxed income and nondeductible officer compensation. For the three month period ended March 31, 2018 , our effective tax rate was lower than the U.S. federal statutory rate of 21% as a result of an enhanced deduction for certain research and development expenses, profits in foreign jurisdictions with reduced income tax rates, the deduction for foreign-derived deduction eligible income, the research and development tax credit, and a tax benefit from disqualifying dispositions of equity awards that do not ordinarily result in a tax benefit, offset by the U.S. tax on global intangible low-taxed income. Our earnings in Hungary are subject to a statutory tax rate of 9% . In addition, our research and development activities in Hungary benefit from a tax law in Hungary that provides for an enhanced deduction for qualified research and development expenses. The tax position of our Hungarian operations resulted in income tax benefits of $1.0 million and $1.7 million for the three month periods ended March 31, 2019 and 2018 , respectively. Earnings from our operations in Malaysia are free of tax under a tax holiday effective January 1, 2013. This tax holiday expires in 2027. If we fail to satisfy the conditions of the tax holiday, this tax benefit may be terminated early. The income tax benefits of the tax holiday for the three months ended March 31, 2019 and March 31, 2018 were approximately $0.5 million and $0.6 million , respectively. The impact of the tax holiday on a per share basis for each of the three months ended March 31, 2019 and March 31, 2018 was a benefit of $0.01 per share. No other taxing jurisdictions had a significant impact on our effective tax rate. We have not entered into any advanced pricing or other agreements with the IRS with regard to any foreign jurisdictions.

Comprehensive Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Comprehensive income	Comprehensive income Our comprehensive income is comprised of net income, foreign currency translation, unrealized gains and losses on forward contracts and securities classified as available-for-sale. The accumulated OCI, net of tax, for the three months ended March 31, 2019 and 2018 , consisted of the following:  March 31, 2019 (Unaudited) (In thousands) Currency translation adjustment Investments Derivative instruments Accumulated other comprehensive income/(loss) Balance as of December 31, 2018 $ (22,485 ) $ (1,308 ) 6,862 $ (16,931 ) Current-period other comprehensive income (loss) (3,067 ) 1,175 3,006 1,114 Reclassified from accumulated OCI into income — — (1,794 ) (1,794 ) Income tax benefit (expense) — (6 ) 216 210 Balance as of March 31, 2019 $ (25,552 ) $ (127 ) $ 7,858 $ (17,821 )  March 31, 2018  (Unaudited) (In thousands) Currency translation adjustment Investments Derivative instruments Accumulated other comprehensive income/(loss) Balance as of December 31, 2017 $ (12,717 ) $ (782 ) (3,010 ) $ (16,509 ) Current-period other comprehensive income (loss) 5,804 (696 ) (5,594 ) (486 ) Reclassified from accumulated OCI into income — — 1,823 1,823 Income tax benefit (expense) — (65 ) (807 ) (872 ) Balance as of March 31, 2018 $ (6,913 ) $ (1,413 ) $ (5,974 ) $ (14,300 ) ໿

Authorized shares of common and

Authorized shares of common and preferred stock and stock-based compensation plans	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Authorized shares of common and preferred stock and stock-based compensation plans	Authorized shares of common and preferred stock and stock-based compensation plans Authorized shares of common and preferred stock Following approval by the Company’s Board of Directors and stockholders, on May 14, 2013, the Company’s certificate of incorporation was amended to increase the authorized shares of common stock by 180,000,000 shares to a total of 360,000,000 shares. As a result of this amendment, the total number of shares which the Company is authorized to issue is 365,000,000 shares, consisting of (i) 5,000,000 shares of preferred stock, par value $0.01 per share, and (ii) 360,000,000 shares of common stock, par value $0.01 per share. Restricted stock plan Our stockholders approved our 2005 Incentive Plan (the “2005 Plan”) in May 2005. At the time of approval, 4,050,000 shares of our common stock were reserved for issuance under this plan, as well as the number of shares which had been reserved but not issued under our 1994 Incentive Plan which terminated in May 2005 (the “1994 Plan”), and any shares that returned to the 1994 Plan as a result of termination of options or repurchase of shares issued under such plan. The 2005 Plan, administered by the Compensation Committee of the Board of Directors, provided for granting of incentive awards in the form of restricted stock and RSUs to directors, executive officers and employees of the Company and its subsidiaries. Awards vest over a three , five or ten -year period, beginning on the date of grant. Vesting of ten year awards may accelerate based on the Company’s previous year’s earnings and growth but ten year awards cannot accelerate to vest over a period of less than five years. The 2005 Plan terminated on May 11, 2010, except with respect to outstanding awards previously granted thereunder. There were 3,362,304 shares of common stock that were reserved but not issued under the 2005 Plan as of May 11, 2010. Our stockholders approved our 2010 Incentive Plan (the “2010 Plan”) on May 11, 2010. At the time of approval, 3,000,000 shares of our common stock were reserved for issuance under this plan, as well as the 3,362,304 shares of common stock that were reserved but not issued under the 1994 Plan and the 2005 Plan as of May 11, 2010, and any shares that are returned to the 1994 Plan and the 2005 Plan as a result of the forfeiture or termination of options or RSUs or repurchase of shares issued under these plans. The 2010 Plan, administered by the Compensation Committee of the Board of Directors, provides for granting of incentive awards in the form of restricted stock and RSUs to employees, directors and consultants of the Company and employees and consultants of any parent or subsidiary of the Company. Awards vest over a three , five or ten -year period, beginning on the date of grant. Vesting of ten year awards may accelerate based on the Company’s previous year’s earnings and growth but ten year awards cannot accelerate to vest over a period of less than five years. The 2010 Plan terminated on May 12, 2015, except with respect to the outstanding awards previously granted thereunder. There were 2,518,416 shares of common stock that were reserved but not issued under the 2010 Plan as of May 12, 2015. Our stockholders approved our 2015 Equity Incentive Plan (the “2015 Plan”) on May 12, 2015. At the time of approval, 3,000,000 shares of our common stock were reserved for issuance under this plan, as well as the 2,518,416 shares of common stock that were reserved but not issued under the 2010 Plan as of May 12, 2015, and any shares that were returned to the 1994, 2005, and the 2010 Plans as a result of the forfeiture or termination of options or RSUs or repurchase of shares issued under these plans. The 2015 Plan, administered by the Compensation Committee of the Board of Directors, provides for the granting of incentive awards in the form of restricted stock and RSUs, to employees, directors and consultants of the Company and employees and consultants of any parent or subsidiary of the Company and such awards may be subject to performance-based vesting conditions. Awards vest over a three , four , five or ten -year period, beginning on the date of grant. Vesting of ten year awards may accelerate based on the Company’s previous year’s earnings and growth but ten year awards cannot accelerate to vest over a period of less than five years. There were 2,705,610 shares available for grant under the 2015 Plan at March 31, 2019 . During the three month period ended March 31, 2019 , we granted PRSUs to certain executives under our 2015 Plan. Refer to the "Summary of Significant Accounting Policies" in Note 1 - Basis of presentation for additional discussion regarding the impact of these new grants on our accounting policies and related estimates. Employee stock purchase plan Our employee stock purchase plan permits substantially all domestic employees and employees of designated subsidiaries to acquire our common stock at a purchase price of 85% of the lower of the market price at the beginning or the end of the purchase period. The plan has quarterly purchase periods generally beginning on February 1, May 1, August 1 and November 1 of each year. Employees may designate up to 15% of their compensation for the purchase of common stock under this plan. On May 9, 2017, our stockholders approved an additional 3,000,000 shares for issuance under our employee stock purchase plan. At March 31, 2019 , we had 1,749,934 shares of common stock reserved for future issuance under this plan. We issued 245,110 shares under this plan in the three months ended March 31, 2019 and the weighted average purchase price of the shares issued was $37.59 per share. During the three months ended March 31, 2019 , we did not make any changes in accounting principles or methods of estimates with respect to such plan. Authorized Preferred Stock and Preferred Stock Purchase Rights Plan We have 5,000,000 authorized shares of preferred stock. On January 21, 2004, our Board of Directors designated 750,000 of these shares as Series A Participating Preferred Stock in conjunction with the adoption of a Preferred Stock Rights Agreement which expired on May 10, 2014. There were no shares of preferred stock issued and outstanding at March 31, 2019 . Stock repurchases and retirements From time to time, our Board of Directors has authorized various programs for our repurchase of shares of our common stock depending on market conditions and other factors. Under the current program, we repurchased 1,035,098 shares of our common stock at a weighted average price per share of $44.83 during the three months ended March 31, 2019 . We did not make any repurchases during the three months ended March 31, 2018 . At March 31, 2019 , there were 2,964,902 shares remaining available for repurchase under this program. This repurchase program does not have an expiration date.

Segment and geographic informat

Segment and geographic information	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Segment and geographic information	Segment and geographic information We operate as one operating segment. Operating segments are defined as components of an enterprise for which separate financial information is evaluated regularly by the chief operating decision maker, who is our chief executive officer, in deciding how to allocate resources and in assessing performance. Our chief operating decision maker evaluates our financial information and resources and assesses the performance of these resources on a consolidated basis. Since we operate in one operating segment, all required financial segment information can be found in the condensed consolidated financial statements and the notes thereto. We sell our products in three geographic regions which consist of Americas; Europe, Middle East, India, and Africa (EMEIA); and Asia-Pacific (APAC). Our sales to these regions share similar economic characteristics, similar product mix, similar customers, and similar distribution methods. Revenue from the sale of our products, which are similar in nature, and software maintenance is reflected as total net sales in our Consolidated Statements of Income. (See Note 2 –Revenue of Notes to consolidated financial statements for total net sales by the major geographic areas in which we operate). Based on the billing location of the customer, total sales outside the U.S. for the three months ended March 31, 2019 and 2018 were $198 million and $200 million , respectively. Total property and equipment, net, outside the U.S. was $115 million and $132 million as of March 31, 2019 and December 31, 2018 . See Note 1 - Basis of presentation for additional information regarding the impact of the new lease accounting standard on our consolidated balance sheet.

Debt

Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt	Debt On May 9, 2013, we entered into a Loan Agreement (the “Loan Agreement”) with Wells Fargo Bank (the “Lender”). The Loan Agreement provided for a $50 million unsecured revolving line of credit with a scheduled maturity date of May 9, 2018 (the “Maturity Date”). On October 29, 2015, we entered into a First Amendment to Loan Agreement (the “Amendment”) with the Lender, which amended our Loan Agreement to among other things, (i) increase the unsecured revolving line of credit from $50 million to $125 million , (ii) extend the Maturity Date of the line of credit from May 9, 2018 to October 29, 2020, and (iii) provide us with an option to request increases to the line of credit of up to an additional $25 million in the aggregate, subject to consent of the Lender and terms and conditions to be mutually agreed between us and the Lender. On April 27, 2018, we entered into a Second Amendment to Loan Agreement (the "Second Amendment") which amended the Loan Agreement, as amended by the Amendment to, among other things, (i) reduce the revolving line of credit from $125.0 million to $5.0 million , (ii) reduce the letter of credit sublimit under the line of credit from $10.0 million to $5.0 million and (iii) require us and our subsidiaries to comply with certain of the affirmative and negative covenants under the Loan Agreement only if loans are outstanding under the Loan Agreement or if we have not reimbursed any drawing under a letter of credit issued under the Loan Agreement within five business days following the request of the Lender. The loans bear interest, at our option, at a base rate determined in accordance with the Loan Agreement, plus a spread of 0.0% to 0.50% , or a LIBOR rate plus a spread of 1.13% to 2.00% , in each case with such spread determined based on a ratio of consolidated indebtedness to EBITDA, determined in accordance with the Loan Agreement. Principal, together with all accrued and unpaid interest, is due and payable on the Maturity Date. We are also obligated to pay a quarterly commitment fee, payable in arrears, based on the available commitments at a rate of 0.18% to 0.30% , with such rate determined based on the ratio described above. The Loan Agreement contains customary affirmative and negative covenants. The affirmative covenants include, among other things, delivery of financial statements, compliance certificates and notices; payment of taxes and other obligations; maintenance of existence; maintenance of properties and insurance; and compliance with applicable laws and regulations. The negative covenants include, among other things, limitations on indebtedness, liens, mergers, consolidations, acquisitions and sales of assets, investments, changes in the nature of the business, affiliate transactions and certain restricted payments. The Loan Agreement also requires us to maintain a ratio of consolidated indebtedness to EBITDA equal to or less than 3.25 to 1.00 , and a ratio of consolidated EBITDA to interest expense greater than or equal to 3.00 to 1.00 , in each case determined in accordance with the Loan Agreement. As of March 31, 2019 , we were in compliance with all applicable covenants in the Loan Agreement. The Loan Agreement contains customary events of default including, among other things, payment defaults, breaches of covenants or representations and warranties, cross-defaults with certain other indebtedness, bankruptcy and insolvency events, judgment defaults and change in control events, subject to grace periods in certain instances. Upon an event of default, the lender may declare all or a portion of the outstanding obligations payable by us to be immediately due and payable and exercise other rights and remedies provided for under the Loan Agreement. Under certain circumstances, a default interest rate will apply on all obligations during the existence of an event of default under the Loan Agreement at a per annum rate of interest equal to 2.00% above the otherwise applicable interest rate. Proceeds of loans made under the Loan Agreement may be used for working capital and other general corporate purposes. We may prepay the loans under the Loan Agreement in whole or in part at any time without premium or penalty. Certain of our existing and future material domestic subsidiaries are required to guaranty our obligations under the Loan Agreement. As of March 31, 2019 , we had no outstanding borrowings under this line of credit. During the three month periods ended March 31, 2019 and 2018, we incurred no interest expense under this line of credit. As of March 31, 2019 and March 31, 2018 , the weighted-average interest rate on the revolving line of credit was 3.7% and 3.0% , respectively.

Commitments and contingencies

Commitments and contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies We offer a one -year limited warranty on most hardware products which is included in the terms of sale of such products. We also offer optional extended warranties on our hardware products for which the related revenue is recognized ratably over the warranty period. Provision is made for estimated future warranty costs at the time of the sale for the estimated costs that may be incurred under the standard warranty. Our estimate is based on historical experience and product sales during the period. The warranty reserve for the three month periods ended March 31, 2019 and 2018 was as follows:  Three Months Ended March 31, (In thousands) (Unaudited)  2019 2018 Balance at the beginning of the period $ 3,173 $ 2,846 Accruals for warranties issued during the period 626 729 Accruals related to pre-existing warranties (133 ) 230 Settlements made (in cash or in kind) during the period (515 ) (784 ) Balance at the end of the period $ 3,151 $ 3,021 As of March 31, 2019 , we had non-cancelable purchase commitments with various suppliers of customized inventory and inventory components totaling approximately $7.1 million over the next twelve months. As of March 31, 2019 , we had no outstanding guarantees for payment of customs and foreign grants, which are generally payable over the next twelve months.

Restructuring

Restructuring	3 Months Ended
	Mar. 31, 2019
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring Since the first quarter of 2017, we have been taking steps to reduce our overall employee headcount in an effort to minimize job duplication or evaluate where we should shift and centralize activities, improve efficiencies, and rebalance our resources on higher return activities. The timing and scope of our headcount reductions will vary. A summary of the charges in the consolidated statement of operations resulting from our restructuring activities is shown below:  Three Months Ended March 31, (In thousands) (Unaudited)  2019 2018 Cost of sales $ — 28 Research and development 345 146 Sales and marketing 1,981 1,645 General and Administration 990 612 Total restructuring and other related costs $ 3,316 2,431 A summary of balance sheet activity related to the restructuring activity is shown below:  Restructuring Liability  (in thousands) Balance as of December 31, 2018 $ 3,506 Income statement expense 3,316 Cash payments (3,178 ) Balance as of March 31, 2019 $ 3,644 The restructuring liability of $3.6 million at March 31, 2019 relating to this restructuring activity is recorded in the “accrued compensation” line item of the consolidated balance sheet. ໿

Litigation

Litigation	3 Months Ended
	Mar. 31, 2019
Litigation Settlement [Abstract]
Litigation	Litigation We are not currently a party to any material litigation. However, in the ordinary course of our business, we have in the past, are currently and will likely become involved in various legal proceedings, claims, and regulatory, tax or government inquiries and investigations, and could incur uninsured liability in any one or more of them. We also periodically receive notifications from various third parties related to alleged infringement of patents or intellectual property rights, commercial disputes or other matters. No assurances can be given with respect to the extent or outcome of any investigation, litigation or dispute.

Subsequent events

Subsequent events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent events On April 24, 2019 , our Board of Directors declared a quarterly cash dividend of $0.25 per common share, payable on June 3, 2019 , to stockholders of record on May 13, 2019 .

Basis of presentation (Policies

Basis of presentation (Policies)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements	Other Recently Adopted Accounting Pronouncements In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . The ASU expands strategies that qualify for hedge accounting, changes how many hedging relationships are presented in the financial statements, and simplifies the application of hedge accounting in certain situations. On January 1, 2019, we adopted the guidance in ASU 2017-12. Adoption did not have a material impact on our financial statements. We continue to assess opportunities enabled by the new standard to expand our risk management strategies. In August 2018, the Securities and Exchange Commission ("SEC") issued Release No. 33-10532 that amends and clarifies certain financial reporting requirements. The principal change to our financial reporting will be the inclusion of the annual disclosure requirement of changes in stockholders’ equity in Rule 3-04 of Regulation S-X to interim periods. We adopted this new rule beginning with our financial reporting for the quarter ended March 31, 2019. In January 2018, the FASB issued ASU 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which gives entities the option to reclassify to retained earnings tax effects resulting from the Tax Cuts and Jobs Act (the "Act") related to items that the FASB refers to as having been stranded in accumulated other comprehensive income ("OCI"). We adopted ASU 2018-02 effective January 1, 2019, and we did not elect the option to reclassify to retained earnings the tax effects resulting from the Act that are stranded in accumulated OCI. The adoption of the new guidance did not have a material effect on our consolidated financial statements. Recent Accounting Guidance Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The ASU will replace the incurred loss impairment methodology under current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. We will be required to use a forward-looking expected credit loss model for accounts receivables and other financial instruments. This ASU requires instruments measured at amortized cost to be presented at the net amount expected to be collected. Entities are also required to record allowances for available-for-sale debt securities rather than reduce the carrying amount. We do not plan to adopt the ASU earlier than our required effective date of January 1, 2020. We expect that the adoption of the ASU will not have a material impact on our financial statements.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation costs are based on the fair value on the date of grant for all restricted stock units ("RSUs") and on the date of enrollment for the employee stock purchase plan. We recognize compensation expense ratably over the requisite service period of the awards. PRSUs are restricted stock unit awards that vest based on a market condition, currently our stockholder return relative to the total stockholder return of the constituents of the Russell 2000 Index at the end of a three-year performance period. Up to 200% of the full target number of shares subject to each PRSU award are eligible to be earned after the completion of the three-year performance period based on our total stockholder return relative to the total stockholder return of the Russell 2000 Index at the end of the performance period. The fair values of RSUs are estimated using their market price on the date of grant. The fair values of employee stock purchase plans are estimated using the Black-Scholes option-pricing model. The fair values of PRSUs are estimated using a Monte Carlo simulation. The determination of fair value of the PRSUs is affected by our stock price and a number of assumptions including the expected volatility, expected dividend yield and the risk-free interest rate. Our expected volatility at the date of grant was based on the historical volatilities of our stock and the constituents of the Russell 2000 Index over the performance period.
Leases	Leases We determine whether an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use ("ROU") assets and operating lease liabilities (current and non-current) on our consolidated balance sheet. Finance leases are included in property and equipment, other current liabilities, and other long-term liabilities in our consolidated balance sheet. Operating lease ROU assets and operating lease liabilities are recognized based on their present value of the future minimum lease payments over the lease term at commencement date. As none of our leases provide an implicit rate we use our incremental borrowing rate based on the information available as of the commencement date. The operating lease ROU assets also includes any lease payments made and excludes lease incentives and initial direct costs incurred. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components. For office leases we account for the lease and non-lease components as a single lease component. For certain leases, such as equipment and vehicles, we account for the lease and non-lease components separately. Additionally, for certain equipment leases, we apply a portfolio approach to effectively account for the operating lease ROU assets and liabilities.
Earnings Per Share	Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income by the weighted average number of common shares outstanding during each period. Diluted EPS is computed by dividing net income by the weighted average number of common shares and common share equivalents outstanding (if dilutive) during each period. The number of common share equivalents, which includes RSUs, is computed using the treasury stock method.

Basis of presentation (Tables)

Basis of presentation (Tables)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reconciliation Of The Denominators Used To Calculate Basic EPS And Diluted EPS	The reconciliation of the denominators used to calculate basic EPS and diluted EPS for the three months ended March 31, 2019 and 2018 , are as follows:  Three Months Ended March 31,  (In thousands)  (Unaudited)  2019 2018 Weighted average shares outstanding-basic 132,252 131,127 Plus: Common share equivalents RSUs 1,115 1,497 Weighted average shares outstanding-diluted 133,367 132,624
Schedule of Cumulative Effects From Change in Accounting Principle	The cumulative effects of the changes made to our consolidated January 1, 2019 balance sheet for the adoption of the new lease standard were as follows (in thousands): Balance at December 31, 2018 Adjustments Due to ASU 2016-02 Balance at January 1, 2019 Assets Property, plant and equipment, net $ 245,201 $ (18,606 ) $ 226,595 Operating lease right-of-use assets — 68,938 68,938 Liabilities and Stockholders' Equity Operating lease liabilities, current — 18,597 18,597 Operating lease liabilities, non-current — $ 33,853 $ 33,853 Other current liabilities $ 25,913 $ (2,118 ) $ 23,795

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Summary of Disaggregation Of Revenue	Total net sales based on the disaggregation criteria described above are as follows:  Three Months Ended March 31, (In thousands) (Unaudited)  2019 2018 Net sales: Point-in-Time (1) Over Time Total Point-in-Time (1) Over Time Total Americas $ 99,681 22,974 $ 122,655 $ 100,053 19,669 $ 119,722 EMEIA 79,122 19,685 98,807 86,907 18,505 105,412 APAC 81,450 8,162 89,612 78,685 8,078 86,763 Total net sales (1) $ 260,253 50,821 $ 311,074 $ 265,645 46,252 $ 311,897 (1): Net sales contains hedging gains and losses, which do not represent revenues recognized from customers. See Note - 5 Derivatives instruments and hedging activities for more information on the impact of our hedging activities on our results of operations
Summary of Changes in Unearned Revenue	Changes in deferred revenue, current and non-current, during the three months ended March 31, 2019 were as follows: Amount  (In thousands) Deferred Revenue at December 31, 2018 $ 159,924 Deferral of revenue billed in current period, net of recognition 51,562 Recognition of revenue deferred in prior periods (47,995 ) Foreign currency translation impact (762 ) Balance as of March 31, 2019 (unaudited) $ 162,729

Short-term investments (Tables)

Short-term investments (Tables)	3 Months Ended
	Mar. 31, 2019
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Schedule of Available-for-sale Securities Reconciliation	The following tables summarize unrealized gains and losses related to our short-term investments designated as available-for-sale debt securities:  As of March 31, 2019 (In thousands) (Unaudited)  Gross Gross  Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Corporate bonds $ 203,851 $ 915 $ (347 ) $ 204,419 U.S. treasuries and agencies 46,852 27 (1 ) 46,878 Total Short-term investments $ 250,703 $ 942 $ (348 ) $ 251,297 (In thousands) As of December 31, 2018  Gross Gross  Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Corporate bonds $ 235,045 $ 726 $ (1,298 ) $ 234,473 U.S. treasuries and agencies 36,932 2 (11 ) 36,923 Total Short-term investments $ 271,977 $ 728 $ (1,309 ) $ 271,396
Summary of Investments Classified by Contractual Maturity Date	The following tables summarize the contractual maturities of our short-term investments designated as available-for-sale debt securities:  As of March 31, 2019 (In thousands) (Unaudited)  Adjusted Cost Fair Value Due in less than 1 year $ 132,980 $ 133,008 Due in 1 to 5 years 117,723 118,289 Total available-for-sale debt securities $ 250,703 $ 251,297  Due in less than 1 year Adjusted Cost Fair Value Corporate bonds $ 86,128 $ 86,130 U.S. treasuries and agencies 46,852 46,878 Total available-for-sale debt securities $ 132,980 $ 133,008  Due in 1 to 5 years Adjusted Cost Fair Value Corporate bonds $ 117,723 $ 118,289 Total available-for-sale debt securities $ 117,723 $ 118,289

Fair value measurements (Tables

Fair value measurements (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are summarized below:  Fair Value Measurements at Reporting Date Using (In thousands) (Unaudited) Description March 31, 2019 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash and cash equivalents available for sale: Money Market Funds $ 57,584 $ 57,584 $ — $ — Short-term investments available for sale: Corporate bonds 204,419 — 204,419 — U.S. treasuries and agencies 46,878 — 46,878 — Derivatives 10,753 — 10,753 Total Assets $ 319,634 $ 57,584 $ 262,050 $ —  Liabilities Derivatives $ (1,461 ) $ — $ (1,461 ) $ — Total Liabilities $ (1,461 ) $ — $ (1,461 ) $ — (In thousands) Fair Value Measurements at Reporting Date Using Description December 31, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash and cash equivalents available for sale: Money Market Funds $ 62,094 $ 62,094 $ — $ — Corporate notes and bonds 9,979 — 9,979 — Short-term investments available for sale: Corporate bonds 234,473 — 234,473 — Time deposits 36,923 — 36,923 — Derivatives 9,369 — 9,369 — Total Assets $ 352,838 $ 62,094 $ 290,744 $ —  Liabilities Derivatives $ (1,483 ) $ — $ (1,483 ) $ — Total Liabilities $ (1,483 ) $ — $ (1,483 ) $ —

Derivative instruments and he_2

Derivative instruments and hedging activities (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Notional Amounts Of Derivative Instruments	We held forward contracts designated as cash flow hedges with the following notional amounts: (In thousands) US Dollar Equivalent  As of March 31, 2019 As of December 31,  (Unaudited) 2018 Chinese yuan 79,931 $ 45,520 Euro 141,484 134,654 Japanese yen 22,543 15,141 Hungarian forint 32,192 35,384 British pound 8,892 9,948 Malaysian ringgit 25,245 27,778 Korean won 13,608 8,331 Total forward contracts notional amount $ 323,895 $ 276,756
Summary of Fair Value Of Derivative Instruments On Consolidated Balance Sheets	The following tables present the fair value of derivative instruments on our Consolidated Balance Sheets at March 31, 2019 and December 31, 2018 , respectively.  Asset Derivatives  March 31, 2019 December 31, 2018 (In thousands) (Unaudited)   Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments Foreign exchange contracts - ST forwards Prepaid expenses and other current assets $ 7,811 Prepaid expenses and other current assets $ 7,594 Foreign exchange contracts - LT forwards Other long-term assets 2,487 Other long-term assets 1,380 Total derivatives designated as hedging instruments $ 10,298 $ 8,974 Derivatives not designated as hedging instruments Foreign exchange contracts - ST forwards Prepaid expenses and other current assets $ 455 Prepaid expenses and other current assets $ 395 Total derivatives not designated as hedging instruments $ 455 $ 395 Total derivatives $ 10,753 $ 9,369  Liability Derivatives  March 31, 2019 December 31, 2018 (In thousands) (Unaudited)  Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments Foreign exchange contracts - ST forwards Other current liabilities $ (763 ) Other current liabilities $ (662 )  Foreign exchange contracts - LT forwards Other long-term liabilities (225 ) Other long-term liabilities (191 ) Total derivatives designated as hedging instruments $ (988 ) $ (853 )  Derivatives not designated as hedging instruments  Foreign exchange contracts - ST forwards Other current liabilities $ (473 ) Other current liabilities $ (630 ) Total derivatives not designated as hedging instruments $ (473 ) $ (630 )  Total derivatives $ (1,461 ) $ (1,483 )
Summary of Derivative Instruments, Gain (Loss)	The following tables present the effect of derivative instruments on our Consolidated Statements of Income for three month periods ended March 31, 2019 and 2018 , respectively: March 31, 2019 (In thousands) (Unaudited) Derivatives in Cash Flow Hedging Relationship Gain or (Loss) Recognized in OCI on Derivative Location of Gain or (Loss) Reclassified from Accumulated OCI into Income Gain or (Loss) Reclassified from Accumulated OCI into Income Foreign exchange contracts - forwards $ 1,800 Net sales $ 1,745  Foreign exchange contracts - forwards (270 ) Cost of sales 20  Foreign exchange contracts - forwards (318 ) Operating expenses 29 Total $ 1,212 $ 1,794 March 31, 2018 (In thousands) (Unaudited) Derivatives in Cash Flow Hedging Relationship Gain or (Loss) Recognized in OCI on Derivative Location of Gain or (Loss) Reclassified from Accumulated OCI into Income Gain or (Loss) Reclassified from Accumulated OCI into Income Foreign exchange contracts - forwards $ (5,073 ) Net sales $ (2,620 )  Foreign exchange contracts - forwards 726 Cost of sales 341  Foreign exchange contracts - forwards 576 Operating expenses 456 Total $ (3,771 ) $ (1,823 ) (In thousands) Derivatives not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income Amount of Gain (Loss) Recognized in Income Amount of Gain (Loss) Recognized in Income  March 31, 2019 March 31, 2018  (Unaudited) (Unaudited) Foreign exchange contracts - forwards Net foreign exchange gain/(loss) $ (228 ) (1,761 )  Total $ (228 ) $ (1,761 )

Inventories, net (Tables)

Inventories, net (Tables)	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventories, net consist of the following:  March 31, 2019 December 31, (In thousands) (Unaudited) 2018  Raw materials $ 102,186 $ 98,346 Work-in-process 9,708 9,306 Finished goods 92,816 86,494  $ 204,710 $ 194,146

Intangible assets and goodwill

Intangible assets and goodwill (Tables)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	Intangible assets at March 31, 2019 and December 31, 2018 are as follows:  March 31, 2019 (In thousands) (Unaudited) December 31, 2018  Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Capitalized software development costs $ 125,857 $ (55,785 ) $ 70,072 $ 123,842 $ (49,299 ) $ 74,543 Acquired technology 91,901 (85,502 ) 6,399 92,236 (84,962 ) 7,274 Patents 34,542 (22,213 ) 12,329 34,427 (21,725 ) 12,702 Other 46,214 (30,948 ) 15,266 46,437 (30,173 ) 16,264  $ 298,514 $ (194,448 ) $ 104,066 $ 296,942 $ (186,159 ) $ 110,783
Schedule of Goodwill	The carrying amount of goodwill as of March 31, 2019 , was as follows:  Amount  (In thousands) Balance as of December 31, 2018 $ 264,530 Foreign currency translation impact (2,146 ) Balance as of March 31, 2019 (unaudited) $ 262,384

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Components of Lease Expense	The components of operating lease expense were as follows (unaudited): (In thousands) March 31, 2019 Operating Lease Cost (a) $ 5,725 (a) includes variable and short-term lease costs Supplemental cash flow information related to operating leases were as follows (unaudited): (In thousands) March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases 4,791 Supplemental non-cash information: Operating lease right-of-use assets obtained in exchange for new operating lease obligations 6,334
Schedule of Future Minimum Lease Payments	Maturities of lease liabilities as of March 31, 2019 were as follows (unaudited): (In thousands) Years ending December 31, Operating Leases 2019 (Excluding the three months ended March 31, 2019) $ 15,280 2020 15,295 2021 10,512 2022 7,573 2023 6,669 Thereafter 14,936 Total future minimum lease payments 70,265 Less imputed interest (16,023 ) Total $ 54,242 Weighted Average Remaining Lease Term (years) Operating Leases 5.22 Weighted Average Discount Rate Operating Leases 6.0 %

Comprehensive income (Tables)

Comprehensive income (Tables)	3 Months Ended
	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Summary of Comprehensive Income (Loss)	The accumulated OCI, net of tax, for the three months ended March 31, 2019 and 2018 , consisted of the following:  March 31, 2019 (Unaudited) (In thousands) Currency translation adjustment Investments Derivative instruments Accumulated other comprehensive income/(loss) Balance as of December 31, 2018 $ (22,485 ) $ (1,308 ) 6,862 $ (16,931 ) Current-period other comprehensive income (loss) (3,067 ) 1,175 3,006 1,114 Reclassified from accumulated OCI into income — — (1,794 ) (1,794 ) Income tax benefit (expense) — (6 ) 216 210 Balance as of March 31, 2019 $ (25,552 ) $ (127 ) $ 7,858 $ (17,821 )  March 31, 2018  (Unaudited) (In thousands) Currency translation adjustment Investments Derivative instruments Accumulated other comprehensive income/(loss) Balance as of December 31, 2017 $ (12,717 ) $ (782 ) (3,010 ) $ (16,509 ) Current-period other comprehensive income (loss) 5,804 (696 ) (5,594 ) (486 ) Reclassified from accumulated OCI into income — — 1,823 1,823 Income tax benefit (expense) — (65 ) (807 ) (872 ) Balance as of March 31, 2018 $ (6,913 ) $ (1,413 ) $ (5,974 ) $ (14,300 )

Commitments and contingencies (

Commitments and contingencies (Tables)	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Product Warranty Liability	The warranty reserve for the three month periods ended March 31, 2019 and 2018 was as follows:  Three Months Ended March 31, (In thousands) (Unaudited)  2019 2018 Balance at the beginning of the period $ 3,173 $ 2,846 Accruals for warranties issued during the period 626 729 Accruals related to pre-existing warranties (133 ) 230 Settlements made (in cash or in kind) during the period (515 ) (784 ) Balance at the end of the period $ 3,151 $ 3,021

Restructuring (Tables)

Restructuring (Tables)	3 Months Ended
	Mar. 31, 2019
Restructuring and Related Activities [Abstract]
Summary of Restructuring Related Costs	A summary of the charges in the consolidated statement of operations resulting from our restructuring activities is shown below:  Three Months Ended March 31, (In thousands) (Unaudited)  2019 2018 Cost of sales $ — 28 Research and development 345 146 Sales and marketing 1,981 1,645 General and Administration 990 612 Total restructuring and other related costs $ 3,316 2,431
Summary of Restructuring Reserve	A summary of balance sheet activity related to the restructuring activity is shown below:  Restructuring Liability  (in thousands) Balance as of December 31, 2018 $ 3,506 Income statement expense 3,316 Cash payments (3,178 ) Balance as of March 31, 2019 $ 3,644

Basis of presentation - Narrat

Basis of presentation - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use assets, after reclassifications		$ 52,000
Operating lease liability	$ 54,242	52,000
Operating lease right-of-use assets	70,861	68,938	$ 0
Property and equipment, net	$ 228,164	226,595	$ 245,201
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		68,938
Property and equipment, net		(18,606)
Accounting Standards Update 2016-02 | Leaseholds and Leasehold Improvements
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		19,000
Property and equipment, net		$ 19,000

Basis of presentation - Schedu

Basis of presentation - Schedule of Cumulative Effect From Adoption of ASU 2014-09 (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets
Property, plant and equipment, net	$ 228,164	$ 226,595	$ 245,201
Operating lease right-of-use assets	70,861	68,938	0
Liabilities and stockholders' equity
Operating lease liabilities - current	16,088	18,597	0
Operating lease liabilities - non-current	38,154	33,853	0
Other current liabilities	$ 27,807	23,795	$ 25,913
Accounting Standards Update 2016-02
Assets
Property, plant and equipment, net		(18,606)
Operating lease right-of-use assets		68,938
Liabilities and stockholders' equity
Operating lease liabilities - current		18,597
Operating lease liabilities - non-current		33,853
Other current liabilities		$ (2,118)

Basis of presentation - Sche_2

Basis of presentation - Schedule of Earnings Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Weighted average shares outstanding - basic	132,252,000	131,127,000
Plus: Common share equivalents
RSUs (in shares)	1,115,000	1,497,000
Weighted average shares outstanding-diluted	133,367,000	132,624,000
Anti-dilutive securities excluded from the computation of diluted EPS (in shares)	67,100	0

Revenue - Schedule of Disaggre

Revenue - Schedule of Disaggregation of Revenues (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)segment	Mar. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Number of operating segments | segment	1
Disaggregation of Revenue [Line Items]
Total net sales	$ 311,074	$ 311,897
Americas
Disaggregation of Revenue [Line Items]
Total net sales	122,655	119,722
EMEIA
Disaggregation of Revenue [Line Items]
Total net sales	98,807	105,412
APAC
Disaggregation of Revenue [Line Items]
Total net sales	89,612	86,763
Point-in-Time
Disaggregation of Revenue [Line Items]
Total net sales	260,253	265,645
Point-in-Time | Americas
Disaggregation of Revenue [Line Items]
Total net sales	99,681	100,053
Point-in-Time | EMEIA
Disaggregation of Revenue [Line Items]
Total net sales	79,122	86,907
Point-in-Time | APAC
Disaggregation of Revenue [Line Items]
Total net sales	81,450	78,685
Over Time
Disaggregation of Revenue [Line Items]
Total net sales	50,821	46,252
Over Time | Americas
Disaggregation of Revenue [Line Items]
Total net sales	22,974	19,669
Over Time | EMEIA
Disaggregation of Revenue [Line Items]
Total net sales	19,685	18,505
Over Time | APAC
Disaggregation of Revenue [Line Items]
Total net sales	$ 8,162	$ 8,078

Revenue - Schedule of Changes

Revenue - Schedule of Changes in Unearned Revenue (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Movement in Deferred Revenue [Roll Forward]
December 31, 2018	$ 159,924
Deferral of revenue billed in current period, net of recognition	51,562
Recognition of revenue deferred in prior periods	(47,995)
Foreign currency translation impact	(762)
March 31, 2019	$ 162,729

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Millions	Mar. 31, 2019USD ($)
Revenue from Contract with Customer [Abstract]
Undelivered performance obligation	$ 57
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percent	37.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percent	35.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percent	28.00%

Short-term investments - Unrea

Short-term investments - Unrealized Gains And Losses Related To Short-Term Investments Designated As Available-For-Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	$ 250,703	$ 271,977
Gross Unrealized Gain	942	728
Gross Unrealized Loss	(348)	(1,309)
Fair Value	251,297	271,396
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	203,851	235,045
Gross Unrealized Gain	915	726
Gross Unrealized Loss	(347)	(1,298)
Fair Value	204,419	234,473
U.S. treasuries and agencies
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	46,852	36,932
Gross Unrealized Gain	27	2
Gross Unrealized Loss	(1)	(11)
Fair Value	$ 46,878	$ 36,923

Short-term investments - Contr

Short-term investments - Contractual Maturities Of Short-Term Investments Designated As Available-For-Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost, Due in less than 1 year	$ 132,980
Fair Value, Due in less than 1 year	133,008
Adjusted Cost, Due in 1 to 5 years	117,723
Fair Value, Due in 1 to 5 years	118,289
Adjusted Cost	250,703	$ 271,977
Fair Value, Total	251,297	271,396
Carrying value of equity method investments	13,000
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost, Due in less than 1 year	86,128
Fair Value, Due in less than 1 year	86,130
Adjusted Cost, Due in 1 to 5 years	117,723
Fair Value, Due in 1 to 5 years	118,289
Fair Value, Total	204,419	234,473
U.S. treasuries and agencies
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost, Due in less than 1 year	46,852
Fair Value, Due in less than 1 year	46,878
Adjusted Cost	46,852	36,932
Fair Value, Total	$ 46,878	$ 36,923

Fair value measurements (Detail

Fair value measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Short-term investments available for sale:
Available-for-sale	$ 251,297	$ 271,396
Derivatives	10,753	9,369
Total Assets	319,634	352,838
Derivatives	(1,461)	(1,483)
Total Liabilities	$ (1,461)	(1,483)
Short-term investments contractual maturity (in months)	60 months
Quoted Prices in Active Markets for Identical Assets (Level 1)
Short-term investments available for sale:
Derivatives	$ 0	0
Total Assets	57,584	62,094
Derivatives	0	0
Total Liabilities	0	0
Significant Other Observable Inputs (Level 2)
Short-term investments available for sale:
Derivatives	10,753	9,369
Total Assets	262,050	290,744
Derivatives	(1,461)	(1,483)
Total Liabilities	(1,461)	(1,483)
Significant Unobservable Inputs (Level 3)
Short-term investments available for sale:
Derivatives		0
Total Assets	0	0
Derivatives	0	0
Total Liabilities	0	0
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale:	57,584	62,094
Money Market Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale:	57,584	62,094
Money Market Funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale:	0	0
Money Market Funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale:	0	0
Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale:		9,979
Corporate notes and bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale:		0
Corporate notes and bonds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale:		9,979
Corporate notes and bonds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale:		0
Corporate bonds
Short-term investments available for sale:
Available-for-sale	204,419	234,473
Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Short-term investments available for sale:
Available-for-sale	0	0
Corporate bonds | Significant Other Observable Inputs (Level 2)
Short-term investments available for sale:
Available-for-sale	204,419	234,473
Corporate bonds | Significant Unobservable Inputs (Level 3)
Short-term investments available for sale:
Available-for-sale	0	0
U.S. treasuries and agencies
Short-term investments available for sale:
Available-for-sale	46,878	36,923
U.S. treasuries and agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Short-term investments available for sale:
Available-for-sale	0
U.S. treasuries and agencies | Significant Other Observable Inputs (Level 2)
Short-term investments available for sale:
Available-for-sale	46,878
U.S. treasuries and agencies | Significant Unobservable Inputs (Level 3)
Short-term investments available for sale:
Available-for-sale	$ 0
Time deposits
Short-term investments available for sale:
Available-for-sale		36,923
Time deposits | Quoted Prices in Active Markets for Identical Assets (Level 1)
Short-term investments available for sale:
Available-for-sale		0
Time deposits | Significant Other Observable Inputs (Level 2)
Short-term investments available for sale:
Available-for-sale		36,923
Time deposits | Significant Unobservable Inputs (Level 3)
Short-term investments available for sale:
Available-for-sale		$ 0

Derivative instruments and he_3

Derivative instruments and hedging activities - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)country	Mar. 31, 2018	Dec. 31, 2018USD ($)
Derivative [Line Items]
Number of countries for which entity has operations (over) | country	50
Percentage of sales outside of the Americas during the period	61.00%	62.00%
Period of protection against the reduction in value caused by a fluctuation, minimum (in number of years)	1 year
Period of protection against the reduction in value caused by a fluctuation, maximum (in number of years)	3 years
Foreign currency forward contracts notional amount	$ 323,895		$ 276,756
Cost of sales
Derivative [Line Items]
Gains (losses) expected to be reclassified from AOCI to earnings	(100)
Forward Contracts | Net Sales
Derivative [Line Items]
Gains (losses) expected to be reclassified from AOCI to earnings	7,300
Forward Contracts | Operating Expenses
Derivative [Line Items]
Gains (losses) expected to be reclassified from AOCI to earnings	(100)
Other Derivatives
Derivative [Line Items]
Foreign currency forward contracts notional amount	$ 42,000		$ 71,000
Maximum
Derivative [Line Items]
Duration of derivative contracts entered into by the entity to hedge risk of loss	21 months		24 months
Maximum | Forward Contracts
Derivative [Line Items]
Percentage of derivative risk hedged	100.00%
Duration of derivative contracts entered into by the entity to hedge risk of loss	36 months
Maximum | Other Derivatives
Derivative [Line Items]
Percentage of derivative risk hedged	90.00%
Duration of derivative contracts entered into by the entity to hedge risk of loss	90 days

Derivative instruments and he_4

Derivative instruments and hedging activities - Summary Of Notional Amounts Of Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Total forward contracts notional amount	$ 323,895	$ 276,756
Chinese yuan
Derivative [Line Items]
Total forward contracts notional amount	79,931	45,520
Euro
Derivative [Line Items]
Total forward contracts notional amount	141,484	134,654
Japanese yen
Derivative [Line Items]
Total forward contracts notional amount	22,543	15,141
Hungarian forint
Derivative [Line Items]
Total forward contracts notional amount	32,192	35,384
British pound
Derivative [Line Items]
Total forward contracts notional amount	8,892	9,948
Malaysian ringgit
Derivative [Line Items]
Total forward contracts notional amount	25,245	27,778
Korean won
Derivative [Line Items]
Total forward contracts notional amount	$ 13,608	$ 8,331

Derivative instruments and he_5

Derivative instruments and hedging activities - Fair Value Of Derivative Instruments On Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative assets	$ 10,753	$ 9,369
Derivative liability	(1,461)	(1,483)
Derivatives Designated As Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative assets	10,298	8,974
Derivative liability	(988)	(853)
Derivatives Designated As Hedging Instruments | Foreign Exchange Contract - Short-Term | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative assets	7,811	7,594
Derivatives Designated As Hedging Instruments | Foreign Exchange Contract - Short-Term | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability	(763)	(662)
Derivatives Designated As Hedging Instruments | Foreign Exchange Contracts - Long-Term | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	2,487	1,380
Derivatives Designated As Hedging Instruments | Foreign Exchange Contracts - Long-Term | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative liability	(225)	(191)
Derivatives Not Designated As Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative assets	455	395
Derivative liability	(473)	(630)
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contract - Short-Term | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative assets	455	395
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contract - Short-Term | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability	$ (473)	$ (630)

Derivative instruments and he_6

Derivative instruments and hedging activities - Effect Of Derivative Instruments On Consolidated Statements Of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivatives Designated As Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in OCI on Derivative	$ 1,212	$ (3,771)
Gain or (Loss) Reclassified from Accumulated OCI into Income	1,794	(1,823)
Derivatives Designated As Hedging Instruments | Foreign Exchange Forward | Net Sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in OCI on Derivative	1,800	(5,073)
Gain or (Loss) Reclassified from Accumulated OCI into Income	1,745	(2,620)
Derivatives Designated As Hedging Instruments | Foreign Exchange Forward | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in OCI on Derivative	(270)	726
Gain or (Loss) Reclassified from Accumulated OCI into Income	20	341
Derivatives Designated As Hedging Instruments | Foreign Exchange Forward | Operating Expenses
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in OCI on Derivative	(318)	576
Gain or (Loss) Reclassified from Accumulated OCI into Income	29	456
Derivatives Not Designated As Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(228)	(1,761)
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Forward
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (228)	$ (1,761)

Inventories, net (Details)

Inventories, net (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 102,186	$ 98,346
Work-in-process	9,708	9,306
Finished goods	92,816	86,494
Inventory, Net	$ 204,710	$ 194,146

Intangible assets and goodwil_2

Intangible assets and goodwill - Schedule Of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 298,514	$ 296,942
Accumulated Amortization	(194,448)	(186,159)
Net Carrying Amount	104,066	110,783
Capitalized software development costs
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	125,857	123,842
Accumulated Amortization	(55,785)	(49,299)
Net Carrying Amount	70,072	74,543
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	91,901	92,236
Accumulated Amortization	(85,502)	(84,962)
Net Carrying Amount	6,399	7,274
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	34,542	34,427
Accumulated Amortization	(22,213)	(21,725)
Net Carrying Amount	12,329	12,702
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	46,214	46,437
Accumulated Amortization	(30,948)	(30,173)
Net Carrying Amount	$ 15,266	$ 16,264

Intangible assets and goodwil_3

Intangible assets and goodwill - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)segment	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 9,000,000	$ 8,400,000
Number of operating segments | segment	1
Goodwill impairment	$ 0		$ 0
Capitalized Software Development Costs
Finite-Lived Intangible Assets [Line Items]
Software development costs capitalized	2,400,000	8,000,000
Amortization expense of capitalized software development costs	6,900,000	6,200,000
Costs related to stock based compensation	$ 100,000	$ 300,000
Minimum | Capitalized Software Development Costs
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period (in years)	3 years
Minimum | Acquired Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period (in years)	3 years
Minimum | Patents
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period (in years)	10 years
Maximum | Capitalized Software Development Costs
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period (in years)	6 years
Maximum | Acquired Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period (in years)	8 years
Maximum | Patents
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization period (in years)	17 years

Intangible assets and goodwil_4

Intangible assets and goodwill - Schedule of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Goodwill [Roll Forward]
December 31, 2018	$ 264,530
Foreign currency translation impact	(2,146)
March 31, 2019	$ 262,384

Leases - Summary of Components

Leases - Summary of Components of Lease Expense and Other Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease, weighted average remaining lease term	5 years 80 days
Operating lease, termination period	1 year
Operating lease cost	$ 5,725
Operating cash flows from operating leases	4,791
Operating lease right-of-use assets obtained in exchange for new operating lease obligations	$ 6,334
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, weighted average remaining lease term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, weighted average remaining lease term	95 years
Operating lease, option to extend, term	9 years

Leases - Maturities of Operatin

Leases - Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
Leases [Abstract]
2019 (Excluding the three months ended March 31, 2019)	$ 15,280
2020	15,295
2021	10,512
2022	7,573
2023	6,669
Thereafter	14,936
Total future minimum lease payments	70,265
Less imputed interest	(16,023)
Total	$ 54,242	$ 52,000
Operating lease, weighted average remaining lease term	5 years 80 days
Operating lease, weighted average discount rate	6.00%

Income taxes (Details)

Income taxes (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 80		$ 80
Unrecognized tax benefits	8		$ 9.8
Gross increase in unrecognized tax benefits, current period	0.2
Decrease in unrecognized tax benefits resulting from closing of open tax years	2
Reasonable possibility of future tax benefits	1.5
Accrued interest related to uncertain tax positions	$ 0.7
Effective income tax rate	11.00%	18.00%
U.S. federal statutory rate	21.00%
Hungary statutory tax rate	9.00%
Hungary
Operating Loss Carryforwards [Line Items]
Foreign income tax benefit	$ 1	$ 1.7
Malaysia
Operating Loss Carryforwards [Line Items]
Income tax benefit of tax holiday, amount	$ 0.5	$ 0.6
Income tax benefit of tax holiday (in usd per share)	$ 0.01	$ 0.01

Comprehensive income (Details)

Comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,238,358	$ 1,128,021
Current-period other comprehensive income (loss)	1,114	(486)
Reclassified from accumulated OCI into income	(1,794)	1,823
Income tax benefit (expense)	210	(872)
Ending Balance	1,201,253	1,149,706
Currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(22,485)	(12,717)
Current-period other comprehensive income (loss)	(3,067)	5,804
Reclassified from accumulated OCI into income	0	0
Income tax benefit (expense)	0	0
Ending Balance	(25,552)	(6,913)
Investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,308)	(782)
Current-period other comprehensive income (loss)	1,175	(696)
Reclassified from accumulated OCI into income	0	0
Income tax benefit (expense)	(6)	(65)
Ending Balance	(127)	(1,413)
Derivative instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	6,862	(3,010)
Current-period other comprehensive income (loss)	3,006	(5,594)
Reclassified from accumulated OCI into income	(1,794)	1,823
Income tax benefit (expense)	216	(807)
Ending Balance	7,858	(5,974)
Accumulated other comprehensive income/(loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(16,931)	(16,509)
Ending Balance	$ (17,821)	$ (14,300)

Authorized shares of common a_2

Authorized shares of common and preferred stock and stock-based compensation plans (Details) - $ / shares	May 14, 2013	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	May 09, 2017	May 12, 2015	May 11, 2010	May 31, 2005	Jan. 21, 2004
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional number of shares reserved for issuance	180,000,000
Common stock, authorized (in shares)	360,000,000	360,000,000		360,000,000	3,000,000
Common and preferred stock shares authorized	365,000,000
Preferred stock, authorized (in shares)	5,000,000	5,000,000		5,000,000
Preferred stock, par value per share (in usd per share)	$ 0.01	$ 0.01		$ 0.01
Common stock, par value per share (in usd per share)	$ 0.01	$ 0.01		$ 0.01
Number of shares reserved for issuance						2,518,416	3,362,304
Maximum employee subscription rate		15.00%
Preferred stock, issued (in shares)		0		0
Preferred stock, outstanding (in shares)		0		0
Common stock repurchased (in shares)		1,035,098	0
Shares repurchased, weighted average price (in dollars per share)		$ 44.83
Authorized common stock available for repurchase (in shares)		2,964,902
Four Year Vesting Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)		4 years
Incentive Plan (2005) | Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance								4,050,000
Incentive Plan (2005) | Restricted Stock Plan | Three Year Vesting Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)		3 years
Incentive Plan (2005) | Restricted Stock Plan | Five Year Vesting Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)		5 years
Incentive Plan (2005) | Restricted Stock Plan | Ten Year Vesting Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)		10 years
Incentive Plan (2010)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance						2,518,416
Incentive Plan (2010) | Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, authorized (in shares)							3,000,000
Incentive Plan (2015)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance						3,000,000
Shares available for grant under 2015 restricted stock plan		2,705,610
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of the lower of the market related to purchase of common stock		85.00%
Common stock reserved for future issuance under employee stock purchase plan (in shares)		1,749,934
Shares issued under employee stock purchase plan		245,110
Weighted average purchase price of employees' purchase rights (in usd per share)		$ 37.59
Series A Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, authorized (in shares)									750,000

Segment and geographic inform_2

Segment and geographic information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)segmentregion	Mar. 31, 2018USD ($)	Jan. 01, 2019USD ($)	Dec. 31, 2018USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments | segment	1
Number of geographic regions company operates in | region	3
Total net sales	$ 311,074	$ 311,897
Property, plant and equipment, net	228,164		$ 226,595	$ 245,201
Outside The United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	198,000	$ 200,000
Property, plant and equipment, net	$ 115,000			$ 132,000

Debt (Details)

Debt (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Apr. 27, 2018	Apr. 26, 2018	Oct. 29, 2015	May 09, 2013
Line of Credit Facility [Line Items]
Unsecured revolving line of credit						$ 50,000,000
Ratio of consolidated indebtedness to earnings before interest, taxes, depreciation and amortization, maximum allowed	3.25
Ratio of consolidated earnings before interest, taxes, depreciation and amortization expense, minimum allowed	3
Interest rate in event of default	2.00%
Outstanding borrowing on line of credit	$ 0
Interest expense	$ 0	$ 0
Weighted average interest rate	3.70%	3.00%
First Amendment
Line of Credit Facility [Line Items]
Unsecured revolving line of credit					$ 125,000,000
Optional credit line increase					$ 25,000,000
Second Amendment
Line of Credit Facility [Line Items]
Unsecured revolving line of credit			$ 5,000,000	$ 125,000,000
Letter of credit sublimit			$ 5,000,000	$ 10,000,000
Minimum
Line of Credit Facility [Line Items]
Quarterly commitment fee	0.175%
Maximum
Line of Credit Facility [Line Items]
Quarterly commitment fee	0.30%
Base Rate | Minimum
Line of Credit Facility [Line Items]
Variable interest rate spread	0.00%
Base Rate | Maximum
Line of Credit Facility [Line Items]
Variable interest rate spread	0.50%
London Interbank Offered Rate | Minimum
Line of Credit Facility [Line Items]
Variable interest rate spread	1.125%
London Interbank Offered Rate | Maximum
Line of Credit Facility [Line Items]
Variable interest rate spread	2.00%

Commitments and contingencies

Commitments and contingencies - Narrative (Details)	3 Months Ended
	Mar. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Limited warranty on most hardware products (in number of years)	1 year
Non-cancelable purchase commitments	$ 7,100,000
Outstanding guarantees for payment of customs and foreign grants	$ 0

Commitments and contingencies_2

Commitments and contingencies - Schedule Of Warranty Reserve (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at the beginning of the period	$ 3,173	$ 2,846
Accruals for warranties issued during the period	626	729
Accruals related to pre-existing warranties	(133)	230
Settlements made (in cash or in kind) during the period	(515)	(784)
Balance at the end of the period	$ 3,151	$ 3,021

Restructuring - Restructuring

Restructuring - Restructuring Related Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related costs	$ 3,316	$ 2,431
Cost of sales
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related costs	0	28
Research and development
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related costs	345	146
Sales and marketing
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related costs	1,981	1,645
General and Administration
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related costs	$ 990	$ 612

Restructuring - Restructurin_2

Restructuring - Restructuring Reserve (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Reserve [Roll Forward]
December 31, 2018	$ 3,506
Income statement expense	3,316	$ 2,431
Cash payments	(3,178)
March 31, 2019	$ 3,644

Restructuring - Narrative (Det

Restructuring - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring accrual	$ 3,644	$ 3,506

Subsequent events (Details)

Subsequent events (Details) - $ / shares	Apr. 24, 2019	Mar. 31, 2019	Mar. 31, 2018
Subsequent Event [Line Items]
Dividends declared per share (in dollars per share)		$ 0.25	$ 0.23
Subsequent Event
Subsequent Event [Line Items]
Dividends declared per share (in dollars per share)	$ 0.25

Uncategorized Items - nati-2019

Label	Element	Value
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 8,619,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 8,619,000