Align Technology (ALGN) 10-Q 2 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 26, 2019
Document Documentand Entity Information [Abstract]
Trading Symbol	ALGN
Entity Registrant Name	ALIGN TECHNOLOGY INC
Entity Central Index Key	0001097149
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 Common Stock, Shares Outstanding		80,004,892

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 71,848	$ 95,866
Net change in foreign currency translation adjustment	409	1,042
Change in unrealized gains (losses) on investments, net of tax	84	(129)
Other comprehensive income	493	913
Comprehensive income	$ 72,341	$ 96,779

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net revenues	$ 548,971	$ 436,924
Cost of net revenues	146,875	109,516
Gross profit	402,096	327,408
Operating expenses:
Selling, general and administrative	247,110	199,625
Research and development	37,503	29,591
Impairments and other charges	29,782	0
Total operating expenses	314,395	229,216
Income from operations	87,701	98,192
Interest income	2,633	2,176
Other income (expense), net	(5,746)	177
Net income before provision for income taxes and equity in losses of investee	84,588	100,545
Provision for income taxes	8,796	2,902
Equity in losses of investee, net of tax	3,944	1,777
Net income	$ 71,848	$ 95,866
Net income per share:
Basic (in usd per share)	$ 0.90	$ 1.20
Diluted (in usd per share)	$ 0.89	$ 1.17
Shares used in computing net income per share:
Basic (in shares)	79,860	80,036
Diluted (in shares)	80,687	81,628

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 588,001	$ 636,899
Marketable securities, short-term	144,540	98,460
Equity method investments	41,969	0
Accounts receivable, net of allowance for doubtful accounts of $3,567 and $2,378, respectively	479,281	439,009
Inventories	68,489	55,641
Prepaid expenses and other current assets	116,833	72,470
Total current assets	1,439,113	1,302,479
Marketable securities, long-term	0	9,112
Property, plant and equipment, net	575,267	521,329
Operating lease right-of-use assets	56,384	0
Equity method investments	0	45,913
Goodwill and intangible assets, net	80,329	81,949
Deferred tax assets	57,151	64,689
Other assets	26,186	26,987
Total assets	2,234,430	2,052,458
Current liabilities:
Accounts payable	62,512	64,256
Accrued liabilities	252,754	234,679
Finance lease liabilities	56,100	0
Deferred revenues	433,518	393,138
Total current liabilities	804,884	692,073
Income tax payable	93,463	78,008
Operating lease liabilities	59,307	0
Other long-term liabilities	21,072	29,486
Total liabilities	978,726	799,567
Commitments and contingencies (Notes 9 and 10)
Stockholders’ equity:
Preferred stock, $0.0001 par value (5,000 shares authorized; none issued)	0	0
Common stock, $0.0001 par value (200,000 shares authorized; 80,000 and 79,778 issued and outstanding, respectively)	8	8
Additional paid-in capital	855,956	877,514
Accumulated other comprehensive income (loss), net	(2,281)	(2,774)
Retained earnings	402,021	378,143
Total stockholders’ equity	1,255,704	1,252,891
Total liabilities and stockholders’ equity	$ 2,234,430	$ 2,052,458

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accounts receivable, allowance for doubtful accounts	$ 3,567	$ 2,378
Preferred stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	0	0
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000	200,000
Common stock, shares issued	80,000	79,778
Common stock, shares outstanding	80,000	79,778

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss), Net	Retained Earnings
Beginning Balance (in shares) at Dec. 31, 2017		80,040
Beginning Balance at Dec. 31, 2017	$ 1,154,288	$ 8	$ 886,435	$ 571	$ 267,274
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	95,866				95,866
Net change in unrealized gains (losses) from investments	(129)			(129)
Net change in foreign currency translation adjustment	1,042			1,042
Issuance of common stock relating to employee equity compensation plans (in shares)		500
Issuance of common stock relating to employee equity compensation plans	8,020		8,020
Tax withholdings related to net share settlements of restricted stock units	(47,842)		(47,842)
Common stock repurchased and retired (shares)		(396)
Common stock repurchased and retired	(100,000)		(3,811)		(96,189)
Stock-based compensation	15,830		15,830
Other	385				385
Ending Balance (in shares) at Mar. 31, 2018		80,144
Ending Balance at Mar. 31, 2018	1,127,460	$ 8	858,632	1,484	267,336
Beginning Balance (in shares) at Dec. 31, 2017		80,040
Beginning Balance at Dec. 31, 2017	1,154,288	$ 8	886,435	571	267,274
Ending Balance (in shares) at Dec. 31, 2018		79,778
Ending Balance at Dec. 31, 2018	1,252,891	$ 8	877,514	(2,774)	378,143
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	71,848				71,848
Net change in unrealized gains (losses) from investments	84			84
Net change in foreign currency translation adjustment	409			409
Issuance of common stock relating to employee equity compensation plans (in shares)		427
Issuance of common stock relating to employee equity compensation plans	9,609		9,609
Tax withholdings related to net share settlements of restricted stock units	(50,181)		(50,181)
Common stock repurchased and retired (shares)		(205)
Common stock repurchased and retired	(50,000)		(2,030)		(47,970)
Stock-based compensation	21,044		21,044
Ending Balance (in shares) at Mar. 31, 2019		80,000
Ending Balance at Mar. 31, 2019	$ 1,255,704	$ 8	$ 855,956	$ (2,281)	$ 402,021

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 71,848	$ 95,866
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred taxes	7,586	4,069
Depreciation and amortization	22,678	11,434
Impairments on long-lived assets	28,498	0
Impairment on equity investment	3,975	0
Stock-based compensation	21,044	15,830
Equity in losses of investee	3,944	1,777
Other non-cash operating activities	5,101	474
Changes in assets and liabilities:
Accounts receivable	(42,743)	(36,026)
Inventories	(13,280)	(4,002)
Prepaid expenses and other assets	(35,033)	(15,873)
Accounts payable	1,470	5,599
Accrued and other long-term liabilities	(5,183)	(35,466)
Long-term income tax payable	4,808	5,259
Deferred revenues	42,494	28,391
Net cash provided by operating activities	117,207	77,332
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(35,261)	(57,578)
Purchase of marketable securities	(125,823)	0
Proceeds from maturities of marketable securities	80,306	126,825
Proceeds from sales of marketable securities	8,727	9,560
Loan repayment from equity investee	0	30,000
Other investing activities	(2,367)	462
Net cash (used in) provided by investing activities	(74,418)	109,269
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	9,609	8,020
Common stock repurchases	(50,000)	(100,000)
Employees’ taxes paid upon the vesting of restricted stock units	(50,181)	(47,842)
Other financing activities	(2,190)	0
Net cash used in financing activities	(92,762)	(139,822)
Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash	1,089	1,715
Net (decrease) increase in cash, cash equivalents, and restricted cash	(48,884)	48,494
Cash, cash equivalents, and restricted cash at beginning of the period	637,566	450,125
Cash, cash equivalents, and restricted cash at end of the period	$ 588,682	$ 498,619

Investments and Fair Value Meas

Investments and Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Investments and Fair Value Measurements	Investments and Fair Value Measurements Marketable Securities As of March 31, 2019 and December 31, 2018 , the estimated fair value of our short-term and long-term marketable securities, classified as available for sale, are as follows (in thousands): Short-term March 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 38,234 $ — $ — $ 38,234 Corporate bonds 33,240 8 (2 ) 33,246 U.S. government agency bonds 14,253 — (31 ) 14,222 U.S. government treasury bonds 45,854 7 (3 ) 45,858 Foreign bonds 12,960 3 (3 ) 12,960 Certificates of deposit 20 — — 20 Total marketable securities, short-term $ 144,561 $ 18 $ (39 ) $ 144,540 There are no long-term marketable securities as of March 31, 2019. Short-term December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 17,793 $ — $ — $ 17,793 Corporate bonds 45,100 — (48 ) 45,052 U.S. government agency bonds 19,981 — (77 ) 19,904 U.S. government treasury bonds 15,292 — (1 ) 15,291 Certificates of deposit 420 1 (1 ) 420 Total marketable securities, short-term $ 98,586 $ 1 $ (127 ) $ 98,460 Long-term December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Corporate bonds $ 4,957 $ 5 $ (2 ) $ 4,960 U.S. government agency bonds 1,399 8 — 1,407 U.S. government treasury bonds 2,235 9 — 2,244 Certificates of deposit 500 1 — 501 Total marketable securities, long-term $ 9,091 $ 23 $ (2 ) $ 9,112 Cash equivalents are not included in the tables above as the gross unrealized gains and losses are not material. We have no short-term or long-term investments that have been in a continuous material unrealized loss position for greater than twelve months as of March 31, 2019 and December 31, 2018 . Amounts reclassified to earnings from accumulated other comprehensive income (loss), net related to unrealized gains or losses were not material for the three months ended March 31, 2019 and 2018 . For the three months ended March 31, 2019 and 2018 , realized gains or losses were not material. Our fixed-income securities investment portfolio consists of investments that can have a maximum effective maturity of up to 40 months on any individual security. The securities that we invest in are generally deemed to be low risk based on their credit ratings from the major rating agencies. The longer the duration of these securities, the more susceptible they are to changes in market interest rates and bond yields. As interest rates increase, those securities purchased at a lower yield show a mark-to-market unrealized loss. The unrealized losses are due primarily to changes in credit spreads and interest rates. We expect to realize the full value of all these investments upon maturity or sale. The weighted average remaining duration of these securities was approximately five months and four months as of March 31, 2019 and December 31, 2018 , respectively. As the carrying value approximates the fair value for our short-term and long-term marketable securities shown in the tables above, the following table summarizes the fair value of our short-term and long-term marketable securities classified by contractual maturity as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, One year or less $ 144,540 $ 98,460 Due in greater than one year — 9,112 Total available for sale short-term and long-term marketable securities $ 144,540 $ 107,572 Investments in Privately Held Companies Our investments in privately held companies as of March 31, 2019 and December 31, 2018 are as follows (in thousands): March 31, December 31, Equity securities under the equity method investment 1 $ 41,969 $ 45,913 Equity securities without readily determinable fair values 2 $ 5,887 $ 9,862 1 Refer to Note 5 “Equity Method Investments” of the Notes to Condensed Consolidated Financial Statements for more information 2 The equity securities are reported as a nonrecurring investment within other assets in our Condensed Consolidated Balance Sheet. During the three months ended March 31, 2019 , there was approximately $4.0 million of impairment resulting from an observable price change. Fair Value Measurements We measure the fair value of financial assets as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We use the GAAP fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. This hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The three levels of inputs that may be used to measure fair value: Level 1 — Quoted (unadjusted) prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the asset or liability. We obtain fair values for our Level 2 investments. Our custody bank and asset managers independently use professional pricing services to gather pricing data which may include quoted market prices for identical or comparable financial instruments, or inputs other than quoted prices that are observable either directly or indirectly, and we are ultimately responsible for these underlying estimates. Level 3 — Unobservable inputs to the valuation methodology that are supported by little or no market activity and that are significant to the measurement of the fair value of the assets or liabilities. Level 3 assets and liabilities include those whose fair value measurements are determined using pricing models, discounted cash flow methodologies or similar valuation techniques, as well as significant management judgment or estimation. The following tables summarize our financial assets measured at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 (in thousands): Description Balance as of March 31, 2019 Level 1 Level 2 Cash equivalents: Money market funds $ 369,896 $ 369,896 $ — Commercial paper 7,978 — 7,978 Corporate bonds 6,809 — 6,809 Short-term investments: Commercial paper 38,234 — 38,234 Corporate bonds 33,246 — 33,246 U.S. government treasury bonds 45,858 45,858 — U.S. government agency bonds 14,222 — 14,222 Foreign bonds 12,960 — 12,960 Certificates of deposit 20 — 20 Prepaid expenses and other current assets: Israeli funds 3,031 — 3,031 $ 532,254 $ 415,754 $ 116,500 Description Balance as of December 31, 2018 Level 1 Level 2 Cash equivalents: Money market funds $ 431,081 $ 431,081 $ — Commercial paper 4,681 — 4,681 U.S. government treasury bonds 2,195 2,195 — Corporate bonds 3,880 — 3,880 Short-term investments: Commercial paper 17,793 — 17,793 Corporate bonds 45,052 — 45,052 U.S. government agency bonds 19,904 — 19,904 U.S. government treasury bonds 15,291 15,291 — Certificates of deposit 420 — 420 Long-term investments: U.S. government agency bonds 1,407 — 1,407 Corporate bonds 4,960 — 4,960 U.S. government treasury bonds 2,244 2,244 — Certificates of deposit 501 — 501 Prepaid expenses and other current assets: Israeli funds 3,047 — 3,047 $ 552,456 $ 450,811 $ 101,645 Derivative Financial Instruments We enter into foreign currency forward contracts to minimize the short-term impact of foreign currency exchange rate fluctuations on certain trade and intercompany receivables and payables. These forward contracts are classified within Level 2 of the fair value hierarchy. The gain from the settlement of foreign currency forward contracts during the three months ended March 31, 2019 was not material. There was no net gain or loss from the settlement of foreign currency forward contracts during the three months ended March 31, 2018. As of March 31, 2019 , the fair value of foreign exchange forward contracts outstanding was not material. The following table presents the gross notional value of all our foreign exchange forward contracts outstanding as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 Local Currency Amount Notional Contract Amount (USD) Euro €73,000 $ 82,059 Chinese Yuan ¥540,000 80,380 Canadian Dollar C$33,500 25,105 British Pound £16,500 21,508 Japanese Yen ¥2,100,000 18,962 Brazilian Real R$69,000 17,660 Mexican Peso M$115,000 5,942 Australian Dollar A$3,000 2,128 $ 253,744 December 31, 2018 Local Currency Amount Notional Contract Amount (USD) Euro €62,000 $ 71,095 Chinese Yuan ¥375,000 54,515 Brazilian Real R$81,000 20,858 Canadian Dollar C$27,000 19,808 British Pound £13,000 16,635 Japanese Yen ¥1,700,000 15,357 Australian Dollar A$3,000 2,114 $ 200,382

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements have been prepared by Align Technology, Inc. (“we”, “our”, or “Align”) in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”) and contains all adjustments, including normal recurring adjustments, necessary to state fairly our results of operations for the three months ended March 31, 2019 and 2018 , our comprehensive income for the three months ended March 31, 2019 and 2018 , our financial position as of March 31, 2019 , our stockholders’ equity for the three months ended March 31, 2019 and 2018, and our cash flows for the three months ended March 31, 2019 and 2018 . The Condensed Consolidated Balance Sheet as of December 31, 2018 was derived from the December 31, 2018 audited financial statements. It does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S.”). We adopted Accounting Standards Update (“ ASU”) 2016-02, “ Leases ” (Topic 842) in the first quarter of fiscal year 2019 by electing the transition method issued in ASU 2018-11 and the package of practical expedients available in the standard. The standard had a material impact on our Condensed Consolidated Balance Sheet as of March 31, 2019 as we recognized assets and liabilities related to our leases. The adoption did not have an impact to prior periods. The results of operations 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 or any other future period, and we make no representations related thereto. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” “Quantitative and Qualitative Disclosures About Market Risk” and the Consolidated Financial Statements and notes thereto included in Items 7, 7A and 8, respectively, in our Annual Report on Form 10-K for the year ended December 31, 2018 . Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles (“GAAP”) in the U.S. requires our management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates. On an ongoing basis, we evaluate our estimates, including those related to the fair values of financial instruments, valuation of investments in privately held companies, useful lives of intangible assets and property and equipment, revenue recognition, stock-based compensation, long-lived assets and goodwill, income taxes and contingent liabilities, among others. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Significant Accounting Policies Our significant accounting policies are described in Note 1 “Summary of Significant Accounting Policies” of the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K. Significant changes to the Lease policy is discussed below: Lease We lease office and retail spaces, vehicles and office equipment with original lease periods of up to 10 years. We determine if an arrangement is a lease at inception under ASC 842. Operating lease right-of-use (“ROU”) assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. If a lease arrangement does not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use the implicit rate when readily determinable. Our lease terms may include options to extend or terminate the lease which we include in our lease term when it is reasonably certain that we will exercise that option. We have lease agreements with lease and non-lease components which are accounted for as a single lease component. Leases with an initial term of 12 months or less are not recorded on the balance sheet. Recent Accounting Pronouncements (i) New Accounting Updates Recently Adopted In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-02, “ Leases ” (Topic 842) to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The updated guidance is effective for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. In July 2018, the FASB issued ASU 2018-11, “ Leases-Targeted Improvements, ” which p rovides an additional transition method by allowing entities to initially apply the new leases standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings. We adopted the guidance in the first quarter of fiscal year 2019 by electing the transition method issued in ASU 2018-11 and the package of practical expedients available in the standard. The standard had a material impact on our Condensed Consolidated Balance Sheet as of March 31, 2019 as we recognized assets and liabilities related to our leases. The adoption did not have an impact to prior periods. In February 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 the tax effects resulting from the U.S. Tax Cuts and Jobs Act (the “TCJA”) related to items in accumulated other comprehensive income. The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2018 on a retrospective basis and early adoption is permitted. We adopted the standard in the first quarter of fiscal year 2019 which did not have a material impact on our consolidated financial statements and related disclosures. The TCJA did not affect our accumulated other comprehensive income (loss), net, and therefore we did not reclassify any income tax effects from accumulated other comprehensive income (loss), net to our retained earnings. (ii) Recent Accounting Updates Not Yet Effective In June 2016, the FASB issued ASU 2016-13, “ Financial Instruments - Credit Losses ” (Topic 326) . The FASB issued this update to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments in this update replace the existing guidance of incurred loss impairment methodology with an approach that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. In November 2018, the FASB issued ASU 2018-19, “ Codification Improvements to Topic 326, Financial Instruments - Credit Losses ” which clarifies the scope of guidance in the ASU 2016-13 . The updated guidance is effective for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption of the update is permitted in fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU 2017-04, “Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” to simplify the subsequent measurement of goodwill by eliminating step two from the goodwill impairment test. Under the amendments, an entity will recognize an impairment charge for the amount by which the carrying value exceeds the fair value. The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2019 on a prospective basis and early adoption is permitted. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, “ Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement,” to modify the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement . The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2019 on a prospective basis and early adoption is permitted. We are currently evaluating the impact of this guidance on our related disclosures. In August 2018, the FASB issued ASU 2018-15, “ Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract,” to clarify the guidance on the costs of implementing a cloud computing hosting arrangement that is a service contract. Under the amendments, the entity is required to follow the guidance in Subtopic 350-40, Internal-Use Software

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Inventories Inventories consist of the following (in thousands): March 31, December 31, Raw materials $ 29,002 $ 26,119 Work in process 19,710 13,784 Finished goods 19,777 15,738 Total inventories $ 68,489 $ 55,641 Other Assets Other assets consist of the following (in thousands): March 31, December 31, Capitalized commissions $ 10,747 $ 9,185 Equity securities 5,887 9,862 Security deposits 5,038 5,162 Other long-term assets 4,514 2,778 Total other assets $ 26,186 $ 26,987 Accrued Liabilities Accrued liabilities consist of the following (in thousands): March 31, December 31, Accrued payroll and benefits $ 87,603 $ 127,109 Accrued expenses 44,343 39,323 Deferred litigation settlement gain 35,000 — Accrued customer credits and deposits 18,094 12,439 Current operating lease liabilities 15,592 — Accrued warranty 10,233 8,551 Accrued property, plant and equipment 9,901 8,193 Accrued sales return reserve 8,202 6,534 Accrued sales rebate 6,612 5,668 Accrued sales tax and value added tax 5,893 6,276 Accrued professional fees 4,955 6,752 Accrued income taxes 2,255 5,752 Other accrued liabilities 4,071 8,082 Total accrued liabilities $ 252,754 $ 234,679 Warranty We regularly review the balance for accrued warranty and update based on historical warranty trends. Actual warranty costs incurred have not materially differed from those accrued; however, future actual warranty costs could differ from the estimated amounts. Warranty accrual as of March 31, 2019 and 2018 consists of the following activity (in thousands): Three Months Ended 2019 2018 Balance at beginning of period $ 8,551 $ 5,929 Charged to cost of revenues 3,133 2,359 Actual warranty expenditures (1,451 ) (1,631 ) Balance at end of period $ 10,233 $ 6,657 Deferred Revenues Deferred revenues consist of the following (in thousands): March 31, December 31, Deferred revenues - current $ 433,518 $ 393,138 Deferred revenues - long-term 1 19,166 17,051 1 Included in other long-term liabilities within our Condensed Consolidated Balance Sheets During the three months ended March 31, 2019 and March 31, 2018 , we recognized $549.0 million and $436.9 million of revenue, respectively, of which $68.4 million and $47.3 million was included in the deferred revenues balance at December 31, 2018 , and December 31, 2017 , respectively. Our unfilled performance obligations as of March 31, 2019 were $483.8 million . These performance obligations are expected to be recognized over the next one to five years

Leases (Notes)

Leases (Notes)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases We have operating and finance leases for office and retail spaces, vehicles and office equipment. The supplemental balance sheet information consists of following (in thousands): Leases March 31, Operating leases: Operating lease right-of-use assets 1 $ 56,384 Accrued liabilities $ 15,592 Operating lease liabilities 59,307 Total operating lease liabilities $ 74,899 Finance leases: Property, plant and equipment, net $ 50,655 Finance lease liabilities $ 56,100 1 The balance is net of impairment charges recorded in the first quarter of 2019. Refer to Note 8“Impairments and Other Charges” of the Notes to Condensed Consolidated Financial Statements for more information The components of lease expenses consists of following (in thousands): Lease Cost Three Months Ended Operating lease cost 1 $ 5,301 Finance lease cost: Amortization of leased assets 1 $ 409 Interest on lease liabilities 2 392 Total finance lease cost $ 801 1 Included in operating expenses on our Condensed Consolidated Statement of Operations 2 Included in other income (expense), net on our Condensed Consolidated Statement of Operations Remaining Lease Term and Discount Rate March 31, Weighted average remaining lease term (in years) Operating leases 5.8 Finance leases 1 0 Weighted average discount rate Operating leases 4.7 % Finance leases 4.2 % 1 On April 5, 2019, we paid the balance of the $56.0 million purchase price and closed the Purchase and Sale Agreement. Refer to Note 10“Commitments and Contingencies” of the Notes to Condensed Consolidated Financial Statements for more information Maturities of operating lease liabilities as of March 31, 2019 are as follows (in thousands): Fiscal Year Ending December 31, Operating Leases Finance Leases Remainder of 2019 $ 15,709 $ 56,100 2020 18,148 — 2021 16,398 — 2022 11,915 — 2023 8,899 — Thereafter 13,302 — Total lease payments $ 84,371 $ 56,100 Less: Interest (9,472 ) — Total lease liabilities $ 74,899 $ 56,100 As of March 31, 2019, we had additional operating leases that have not yet commenced of $9.2 million . These operating leases will commence between fiscal year 2019 to 2022 with lease terms of 3 years to 5 years . Minimum future lease payments previously disclosed under ASC 840 in our Annual Report on Form 10-K for the year ended December 31, 2018 (in thousands) are as follows: Fiscal Year Ending December 31, Operating Leases 2019 $ 21,429 2020 20,483 2021 18,897 2022 15,096 2023 12,400 Thereafter 18,371 Total minimum lease payments $ 106,676
Leases	Leases We have operating and finance leases for office and retail spaces, vehicles and office equipment. The supplemental balance sheet information consists of following (in thousands): Leases March 31, Operating leases: Operating lease right-of-use assets 1 $ 56,384 Accrued liabilities $ 15,592 Operating lease liabilities 59,307 Total operating lease liabilities $ 74,899 Finance leases: Property, plant and equipment, net $ 50,655 Finance lease liabilities $ 56,100 1 The balance is net of impairment charges recorded in the first quarter of 2019. Refer to Note 8“Impairments and Other Charges” of the Notes to Condensed Consolidated Financial Statements for more information The components of lease expenses consists of following (in thousands): Lease Cost Three Months Ended Operating lease cost 1 $ 5,301 Finance lease cost: Amortization of leased assets 1 $ 409 Interest on lease liabilities 2 392 Total finance lease cost $ 801 1 Included in operating expenses on our Condensed Consolidated Statement of Operations 2 Included in other income (expense), net on our Condensed Consolidated Statement of Operations Remaining Lease Term and Discount Rate March 31, Weighted average remaining lease term (in years) Operating leases 5.8 Finance leases 1 0 Weighted average discount rate Operating leases 4.7 % Finance leases 4.2 % 1 On April 5, 2019, we paid the balance of the $56.0 million purchase price and closed the Purchase and Sale Agreement. Refer to Note 10“Commitments and Contingencies” of the Notes to Condensed Consolidated Financial Statements for more information Maturities of operating lease liabilities as of March 31, 2019 are as follows (in thousands): Fiscal Year Ending December 31, Operating Leases Finance Leases Remainder of 2019 $ 15,709 $ 56,100 2020 18,148 — 2021 16,398 — 2022 11,915 — 2023 8,899 — Thereafter 13,302 — Total lease payments $ 84,371 $ 56,100 Less: Interest (9,472 ) — Total lease liabilities $ 74,899 $ 56,100 As of March 31, 2019, we had additional operating leases that have not yet commenced of $9.2 million . These operating leases will commence between fiscal year 2019 to 2022 with lease terms of 3 years to 5 years . Minimum future lease payments previously disclosed under ASC 840 in our Annual Report on Form 10-K for the year ended December 31, 2018 (in thousands) are as follows: Fiscal Year Ending December 31, Operating Leases 2019 $ 21,429 2020 20,483 2021 18,897 2022 15,096 2023 12,400 Thereafter 18,371 Total minimum lease payments $ 106,676

Equity Method Investments

Equity Method Investments	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method Investments On July 25, 2016, we acquired a 17% equity interest, on a fully diluted basis, in SmileDirectClub, LLC (“SDC”) for $46.7 million . On July 24, 2017, we purchased an additional 2% equity interest in SDC for $12.8 million . The investment is accounted for as an equity method investment and the investee, SDC, is considered a related party. The investment is reported in our Condensed Consolidated Balance Sheets under equity method investments which was reclassed to short-term asset as of March 31, 2019 due to arbitration ordered to tender our interest by April 3, 2019. We record our proportional share of SDC’s losses within equity in losses of investee, net of tax, in our Condensed Consolidated Statement of Operations. As of March 31, 2019 and December 31, 2018 , the balance of our equity method investments was $42.0 million and $45.9 million , respectively. Concurrently with the investment on July 25, 2016, we also entered into a supply agreement with SDC to manufacture clear aligners for SDC’s doctor-led, at-home program for simple teeth straightening. The term of the supply agreement expires on December 31, 2019. The sale of aligners to SDC and the income from the supply agreement are reported in our Clear Aligner business segment. We eliminate unrealized profit on outstanding intercompany transactions. As of March 31, 2019 and December 31, 2018 , the balance of accounts receivable due from SDC was $18.0 million and $16.3 million , respectively. For the three months ended March 31, 2019 and 2018 , net revenues recognized from SDC was $5.7 million and $5.3 million , respectively. On July 25, 2016, we entered into a Loan and Security Agreement (the “Loan Agreement”) with SDC and amended on July 24, 2017 where we agreed to provide SDC a loan of up to $30.0 million in one or more advances. On February 7, 2018, $30.0 million of outstanding loan advances and related accrued interest were repaid in full, and the Loan Agreement was terminated. As a result of the arbitrator’s decision regarding SDC announced on March 5, 2019, Align was ordered to tender its SDC equity interest by April 3, 2019 for a purchase price equal to the “capital account” balance as of October 31, 2017 under the terms of the investment. In April 2019, based on “capital account” value provided by SDC, Align entered into unsecured promissory note receivable with SDC to receive approximately $54.2 million through February 1, 2021 in exchange for equity interest. As a result, we expect to record a gain of approximately $16 million in the second quarter of 2019 as other income in our Condensed Consolidated Statement of Operation. Although we tendered our members interests pursuant to the arbitrators decision, the parties did not agree on the amount of SDC’s “capital account” balance as of October 31, 2017 or the appropriate repurchase price for the membership units. We intend to seek a re-valuation of Align’s “capital account” balance as of October 31, 2017, which may increase the amount of the unsecured promissory note and recognize additional other income ( Refer to Note 9 “Legal Proceedings” of the Notes to Condensed Consolidated Financial Statements

Goodwill and Long-lived Assets

Goodwill and Long-lived Assets	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill The change in the carrying value of goodwill for the three months ended March 31, 2019 , all attributable to our Clear Aligner reporting unit, is as follows (in thousands): Total Balance as of December 31, 2018 $ 64,029 Adjustments 1 (22 ) Balance as of March 31, 2019 $ 64,007 1 The adjustments to goodwill during the period were a result of foreign currency translation During the fourth quarter of fiscal 2018 , we performed the annual goodwill impairment testing and found no impairment as the fair value of our Clear Aligner reporting unit was significantly in excess of the carrying value. Intangible Long-Lived Assets Acquired intangible long-lived assets are being amortized as follows (in thousands): Weighted Average Amortization Period (in years) Gross Carrying Amount as of March 31, 2019 Accumulated Amortization Accumulated Impairment Loss Net Carrying Trademarks 15 $ 7,100 $ (1,942 ) $ (4,179 ) $ 979 Existing technology 13 12,600 (5,408 ) (4,328 ) 2,864 Customer relationships 11 33,500 (17,008 ) (10,751 ) 5,741 Reacquired rights 3 7,500 (5,066 ) — 2,434 Patents 8 6,796 (2,542 ) — 4,254 Other 2 618 (568 ) — 50 Total intangible assets $ 68,114 $ (32,534 ) $ (19,258 ) $ 16,322 Weighted Average Amortization Period (in years) Gross Carrying Amount as of December 31, 2018 Accumulated Amortization Accumulated Impairment Loss Net Carrying Value as of December 31, 2018 Trademarks 15 $ 7,100 $ (1,907 ) $ (4,179 ) $ 1,014 Existing technology 13 12,600 (5,268 ) (4,328 ) 3,004 Customer relationships 11 33,500 (16,542 ) (10,751 ) 6,207 Reacquired rights 3 7,500 (4,341 ) — 3,159 Patents 8 6,796 (2,334 ) — 4,462 Other 2 618 (544 ) — 74 Total intangible assets $ 68,114 $ (30,936 ) $ (19,258 ) $ 17,920 The total estimated annual future amortization expense for these acquired intangible assets as of March 31, 2019 is as follows (in thousands): Fiscal Year Ending December 31, Amortization Remainder of 2019 $ 4,544 2020 3,838 2021 3,389 2022 2,116 2023 1,495 Thereafter 940 Total $ 16,322 Amortization for the three months ended March 31, 2019 and 2018 was $1.5 million and $1.4 million

Credit Facilities

Credit Facilities	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Credit Facilities	Credit Facilities On February 27, 2018, we entered into a new credit facility for a $200.0 million revolving line of credit, with a $50.0 million letter of credit sublimit, and a maturity date of February 27, 2021, replacing the existing credit facility which provided for a $50.0 million revolving line of credit with a $10.0 million letter of credit. The credit facility requires us to comply with specific financial conditions and performance requirements. The loans bear interest, at our option, at either a rate based on the reserve adjusted LIBOR for the applicable interest period or a base rate, in each case plus a margin. The base rate is the highest of the credit facility’s publicly announced prime rate, the federal funds rate plus 0.50% and one month LIBOR plus 1.0% . The margin ranges from 1.25% to 1.75% for LIBOR loans and 0.25% to 0.75% for base rate loans. Interest on the loans is payable quarterly in arrears with respect to base rate loans and at the end of an interest period (and at three month intervals if the interest period exceeds three months) in the case of LIBOR loans. Principal, together with accrued and unpaid interest, is due on the maturity date. As of March 31, 2019 , we had no

Impairments and Other Charges (

Impairments and Other Charges (Notes)	3 Months Ended
	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Impairments and Other Charges	Impairments and Other Charges On March 5, 2019, we announced the outcome of the arbitration regarding SDC ( Refer to Note 9 “Legal Proceedings” of the Notes to Condensed Consolidated Financial Statements for SDC legal proceedings discussion) which required Align to close its Invisalign stores and tender Align’s equity interest in SDC by April 3, 2019. Accordingly, Align evaluated the ongoing value of the Invisalign stores’ operating lease right-of-use assets and related leasehold improvements and other fixed assets in accordance with ASC 360, Property, Plant and Equipment . Based on the evaluation, Align determined that the carrying value of these assets were not recoverable. Align evaluated the fair value of these assets in accordance with ASC 820, Fair Value Measurement, and we considered the market participant’s ability to generate economic benefits by using these assets in its highest and best use or by selling it to another market participant that would use the asset in its highest and best use. As a result, Align recorded impairment losses of $14.2 million for operating lease right-of-use assets and $14.3 million of leasehold improvements and other fixed assets. In addition, we also recorded $1.3 million

Legal Proceedings (Notes)

Legal Proceedings (Notes)	3 Months Ended
	Mar. 31, 2019
Legal Proceedings [Abstract]
Legal Proceedings	Legal Proceedings Securities Class Action Lawsuit On November 5, 2018, a class action lawsuit against Align, and three of our executive officers, was filed in the U.S. District Court for the Northern District of California on behalf of a purported class of purchasers of our common stock between July 25, 2018 and October 24, 2018. The complaint generally alleges claims under the federal securities laws and seeks monetary damages in an unspecified amount and costs and expenses incurred in the litigation. On December 12, 2018, a similar lawsuit was filed in the same court on behalf of a purported class of purchasers of our common stock between April 25, 2018 and October 24, 2018 (together with the first lawsuit, the “Securities Actions”). The Court appointed a lead plaintiff on March 22, 2019 and that lead plaintiff is expected to file a consolidated complaint on May 10, 2019. Align believes these claims are without merit and intends to vigorously defend itself. Align is currently unable to predict the outcome of these lawsuits and therefore cannot determine the likelihood of loss nor estimate a range of possible loss. Shareholder Derivative Lawsuit In January 2019, three derivative lawsuits were also filed in the U.S. District Court for the Northern District of California, purportedly on behalf of Align, naming as defendants the members of our Board of Directors along with certain of our executive officers. The allegations in the complaints are similar to those presented in the Securities Action, but the complaints assert various state law causes of action, including for breaches of fiduciary duty, insider trading, and unjust enrichment, among others. The complaints seek unspecified monetary damages on behalf of Align, which is named solely as a nominal defendant against whom no recovery is sought, as well as disgorgement and the costs and expenses associated with the litigation, including attorneys’ fees. On February 26, 2019, the three lawsuits were consolidated. On April 10, 2019, the Court stayed the consolidated action pending final disposition of the Securities Action. On April 12, 2019, a derivative lawsuit was also filed in California Superior Court for Santa Clara County, purportedly on behalf of Align, naming as defendants the members of our Board of Directors along with certain of our executive officers. The allegations in this complaint are similar to those in the derivative suits described above. Align is currently unable to predict the outcome of these lawsuits and therefore cannot determine the likelihood of loss nor estimate a range of possible loss. 3Shape Litigation On November 14, 2017, Align filed six patent infringement lawsuits asserting 26 patents against 3Shape, a Danish corporation, and a related U.S. corporate entity, asserting that 3Shape’s Trios intraoral scanning system and Dental System software infringe Align patents. Align filed two Section 337 complaints with the U.S. International Trade Commission (“ITC”) alleging that 3Shape violates U.S. trade laws by selling for importation and importing its infringing Trios intraoral scanning system and Dental System software. Align’s ITC complaints seek cease and desist orders and exclusion orders prohibiting the importation of 3Shape’s Trios scanning system and Dental System software products into the U.S. Align also filed four separate complaints in the U.S. District Court for the District of Delaware alleging patent infringement by 3Shape’s Trios intraoral scanning system and Dental System software. Two of those cases are stayed pending the ITC determinations, and the other two cases are currently active in discovery. The ITC conducted hearings in September and November 2018. On March 1, 2019, the Administrative Law Judge issued an Initial Determination in one of the Section 337 investigations, finding no violation of Section 337 by 3Shape. Align and 3Shape each petitioned the Commission for review of the Initial Determination, and the Commission has not yet ruled on those petitions. On April 26, 2019, the Administrative Law Judge issued an Initial Determination in the second Section 337 investigations, finding no violation of Section 337 by 3Shape. Petitions for review by the Commission, if any, are due May 10, 2019. The target dates for completion of the investigations is July 1 and August 26, 2019. On May 9, 2018, 3Shape filed a complaint in the U.S. District Court for the District of Delaware alleging patent infringement by Align’s iTero Element scanner of a single 3Shape patent; the case was subsequently stayed. On June 14, 2018, 3Shape filed another complaint in the U.S. District Court for the District of Delaware alleging patent infringement by Align’s iTero Element scanner of a single 3Shape patent, which remains an active case. On August 28, 2018, 3Shape filed a complaint against Align in the U.S. District Court for the District of Delaware alleging antitrust violations and seeking monetary damages and injunctive relief relating to Align’s market activities, including Align’s assertion of its patent portfolio, in the clear aligner and intraoral scanning markets. Align filed a motion to dismiss 3Shape’s complaint on October 17, 2018, which the Court has yet to rule on. Align has also moved to stay the litigation pending the outcome of its motion to dismiss and/or the patent litigations involving 3Shape. On December 10, 2018, Align filed three additional patent infringement lawsuits asserting 10 additional patents against 3Shape. Align filed one Section 337 complaint with the ITC alleging that 3Shape violates U.S. trade laws through unfair competition by selling for importation and importing the infringing TRIOS intraoral scanning system, Trios Lab Scanners and TRIOS software, TRIOS Module software, Dental System software, and Ortho System Software. On December 11, 2018, Align filed two separate complaints in the U.S. District Court for the District of Delaware alleging patent infringement by 3Shape's Trios intraoral scanning system, Lab Scanners and Dental and Ortho System Software. The ITC instituted the investigation, and one of the District Court cases was stayed pending the ITC determination. 3Shape has sought to invalidate certain of Align’s patents through petitions for inter partes review proceedings. Align disputes 3Shape’s positions and intends to vigorously defend the validity of its patent rights. Each of the District Court patent infringement complaints seek monetary damages and injunctive relief against further infringement. We are currently unable to predict the outcome of this dispute and therefore cannot determine the likelihood of loss, if any, nor estimate a range of possible loss. SDC Dispute In February 2018, we received a communication on behalf of SDC Financial LLC, SmileDirectClub LLC, and the Members of SDC Financial LLC other than the Company (collectively, the SDC Entities) alleging that the launch and operation of the Invisalign store pilot program constitutes a breach of non-compete provisions applicable to the members of SDC Financial LLC, including Align. As a result of this alleged breach, SDC Financial LLC notified us that its members (other than Align) seek to exercise a right to repurchase all of Align's SDC Financial LLC membership interests for a purchase price equal to the current “capital account” balance of Align. The SDC Entities’ communication also alleged that Align breached confidentiality provisions applicable to the SDC Financial LLC members and demanded that Align cease all activities related to the Invisalign store pilot project, close existing Invisalign stores and cease using SDC’s confidential information. In April 2018, the SDC Entities instigated confidential arbitration proceedings and filed a complaint in the Chancery Court of Davidson County, State of Tennessee that sought, among other forms of relief, to preliminarily and permanently enjoin all activities related to the Invisalign store pilot project, require Align to close existing Invisalign stores, prohibit Align from opening any additional stores, and allow the SDC Entities to exercise a right to repurchase all of Align's SDC Financial LLC membership interests for a purchase price equal to Align's current “capital account” balance. On June 29, 2018, the Chancery Court of Davidson County, State of Tennessee denied the SDC Entities’ request for a temporary injunction to prevent Align from opening additional Invisalign stores. During December 2018, the parties participated in binding arbitration proceedings and presented closing arguments on January 23, 2019. The arbitrator issued his decision (the Award) on March 4, 2019. The arbitrator found that Align breached the non-compete provision applicable to the members of SDC Financial LLC, including that Align misused the SDC Entities’ confidential information and violated fiduciary duties to SDC Financial LLC. The arbitrator ordered Align to close its Invisalign stores by April 3, 2019, and enjoined Align from opening new Invisalign stores or providing certain services in physical retail establishments in connection with the marketing and sale of clear aligners, and enjoined Align from using the SDC Entities’ confidential information. The arbitrator extended the expiration date of the non-compete provision to August 18, 2022. The arbitrator also ordered Align to tender its SDC Financial LLC membership interests to the SDC Entities for a purchase price equal to the “capital account” balance as of October 31, 2017, a price which is significantly below the current fair market value of such investment. No financial damages were awarded to the SDC Entities. The SDC Entities filed a motion to confirm the Award, which Align did not oppose, in the Circuit Court for Cook County, Illinois. The motion to confirm the Award is under submission. As required by the Award, on April 3, 2019, Align closed its Invisalign stores, returned SDC’s alleged confidential information, and tendered its memberships interests to certain SDC Entities for a purchase price that SDC claims to be Align’s “capital account” balance as of October 31, 2017. Align disputes the “capital account” balance as of October 31, 2017 as provided by the SDC Entities and anticipate that there may be additional litigation with the SDC Entities regarding the “capital account” balance and other issues relating to the Award and the parties’ relationship. In addition, in the course of Align’s operations, Align is involved in a variety of claims, suits, investigations, and proceedings, including actions with respect to intellectual property claims, patent infringement claims, government investigations, labor and employment claims, breach of contract claims, tax, and other matters. Regardless of the outcome, these proceedings can have an adverse impact on us because of defense costs, diversion of management resources, and other factors. Although the results of complex legal proceedings are difficult to predict and Align’s view of these matters may change in the future as litigation and events related thereto unfold; Align currently does not believe that these matters, individually or in the aggregate, will materially affect Align’s financial position, results of operations or cash flows. Straumann Group Litigation Settlement

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Commitments and Contingencies	Commitments and Contingencies Other Commitments On January 15, 2019, we entered into a Purchase Agreement to purchase five floors of a building under construction in Petach Tivka, Israel (the "Property") for a purchase price of approximately $27.0 million with an option to purchase additional three floors. The purchase price will be paid in six installments according to construction milestones and the delivery of the Property throughout 2019 and 2020. On January 29, 2019, we entered into a Purchase and Sale Agreement to purchase our current finance lease building located in Morrisville, North Carolina for a purchase price of $58.1 million subject to adjustments. In January 2019, we paid a $2.0 million deposit and in April 2019, we paid the remaining balance of the $56.0 million and closed the Purchase and Sale Agreement. Off-Balance Sheet Arrangements As of March 31, 2019 , we had no material off-balance sheet arrangements that have, or are reasonably likely to have, a current or future material effect on our consolidated financial condition, results of operations, liquidity, capital expenditures or capital resources other than certain items disclosed in Note 9 “Commitments and Contingencies” of the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K. Indemnification Provisions In the normal course of business to facilitate transactions in our services and products, we indemnify certain parties: customers, vendors, lessors, and other parties with respect to certain matters, including, but not limited to, services to be provided by us and intellectual property infringement claims made by third parties. In addition, we have entered into indemnification agreements with our directors and our executive officers that will require us, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. Several of these agreements limit the time within which an indemnification claim can be made and the amount of the claim. It is not possible to make a reasonable estimate of the maximum potential amount under these indemnification agreements due to the unique facts and circumstances involved in each particular agreement. Additionally, we have a limited history of prior indemnification claims and the payments we have made under such agreements have not had a material adverse effect on our results of operations, cash flows or financial position. However, to the extent that valid indemnification claims arise in the future, future payments by us could be significant and could have a material adverse effect on our results of operations or cash flows in a particular period. As of March 31, 2019

Stockholders' Equity (Notes)

Stockholders' Equity (Notes)	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Stockholders' Equity	Stockholders’ Equity Summary of Stock-Based Compensation Expense As of March 31, 2019 , the 2005 Incentive Plan (as amended) has a total reserve of 27,783,379 shares of which 5,297,058 shares are available for issuance. Stock-based compensation is based on the estimated fair value of awards, net of estimated forfeitures, and recognized over the requisite service period. Estimated forfeitures are based on historical experience at the time of grant and may be revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The stock-based compensation related to all of our stock-based awards and employee stock purchases for the three months ended March 31, 2019 and 2018 is as follows (in thousands): Three Months Ended 2019 2018 Cost of net revenues $ 1,112 $ 881 Selling, general and administrative 16,890 12,578 Research and development 3,042 2,371 Total stock-based compensation $ 21,044 $ 15,830 Stock Options We have not granted options since 2011 and all outstanding options were fully vested and associated stock-based compensation expenses was recognized as of December 31, 2015. During the three months ended March 31, 2019 , 7,800 stock options were exercised at a weighted average exercise price of $7.89 per share. As of March 31, 2019, options outstanding and exercisable were not material. Restricted Stock Units (“RSUs”) The fair value of RSUs is based on our closing stock price on the date of grant. A summary for the three months ended March 31, 2019 is as follows: Number of Shares Underlying RSUs (in thousands) Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Nonvested as of December 31, 2018 931 $ 129.39 Granted 255 253.84 Vested and released (356 ) 95.18 Forfeited (20 ) 155.77 Nonvested as of March 31, 2019 810 $ 183.06 1.67 $ 230,206 As of March 31, 2019 , we expect to recognize $125.3 million of total unamortized compensation cost, net of estimated forfeitures, related to RSUs over a weighted average period of 2.6 years. Market-performance Based Restricted Stock Units (“MSUs”) We grant MSUs to our executive officers. Each MSU represents the right to one share of Align’s common stock. The actual number of MSUs which will be eligible to vest will be based on the performance of Align’s stock price relative to the performance of a stock market index over the vesting period, and certain MSU grants are also based on Align’s stock price at the end of the performance period. Generally, the vesting period of MSUs is three years . For MSUs granted during the three months ended March 31, 2019 , the maximum number of MSUs which will be eligible to vest are 250% of the MSUs initially granted. The following table summarizes the MSU performance for the three months ended March 31, 2019 : Number of Shares Underlying MSUs (in thousands) Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Nonvested as of December 31, 2018 324 $ 215.07 Granted 133 245.69 Vested and released (179 ) 72.74 Forfeited (5 ) 265.42 Nonvested as of March 31, 2019 273 $ 322.53 1.84 $ 77,513 As of March 31, 2019 , we expect to recognize $58.0 million of total unamortized compensation cost, net of estimated forfeitures, related to MSUs over a weighted average period of 1.8 years. Employee Stock Purchase Plan (“ESPP”) In May 2010, our shareholders approved the 2010 Employee Stock Purchase Plan (the “2010 Purchase Plan”) which will continue until terminated by either the Board of Directors or its administrator. The maximum number of shares available for purchase under the 2010 Purchase Plan is 2,400,000 shares. As of March 31, 2019 , we have 490,417 shares available for future issuance. The fair value of the option component of the 2010 Purchase Plan shares was estimated at the grant date using the Black-Scholes option pricing model with the following weighted average assumptions: Three Months Ended 2019 2018 Expected term (in years) 1.4 1.3 Expected volatility 48.6 % 35.7 % Risk-free interest rate 2.5 % 1.9 % Expected dividends — — Weighted average fair value at grant date $ 90.36 $ 78.38 As of March 31, 2019 , there was $10.3 million of total unamortized compensation costs related to employee stock purchases which we expect to be recognized over a weighted average period of 1.0

Common Stock Repurchase Program

Common Stock Repurchase Programs	3 Months Ended
	Mar. 31, 2019
Disclosure Common Stock Repurchase Program Additional Information [Abstract]
Common Stock Repurchase Programs	Common Stock Repurchase Programs April 2016 Repurchase Program In April 2016, we announced that our Board of Directors had authorized a plan to repurchase up to $300.0 million of our common stock (“April 2016 Repurchase Program”). In 2017, we entered into an accelerated share repurchase agreement ("2017 ASR") to repurchase $50.0 million of our common stock which was completed in August 2017. We received a total of approximately 0.4 million shares for an average share price of $146.48 . During 2017, we repurchased on the open market approximately 0.2 million shares of our common stock at an average price of $243.40 per share, including commissions, for an aggregate purchase price of approximately $50.0 million . In 2018, we repurchased on the open market approximately 0.7 million shares of our common stock at an average price of $293.21 per share, including commissions, for an aggregate purchase price of approximately $200.0 million , completing the April 2016 Repurchase Program. May 2018 Repurchase Program In May 2018, we announced that our Board of Directors had authorized a plan to repurchase up to $600.0 million of our common stock (“May 2018 Repurchase Program”). In 2018, we repurchased on the open market approximately 0.1 million shares of our common stock at an average price of $356.54 per share, including commissions, for an aggregate purchase price of approximately $50.0 million . In 2018, we entered into an accelerated stock repurchase agreement (“2018 ASR”) to repurchase $50.0 million of our common stock which was completed in December 2018. We received a total of approximately 0.2 million shares for an average share price of $213.18 . In February 2019, we purchased on the open market approximately 0.2 million shares of our common stock at an average price of $243.42 per share, including commission for an aggregate purchase price of $50.0 million . As of March 31, 2019 , we have $450.0 million

Accounting for Income Taxes

Accounting for Income Taxes	3 Months Ended
	Mar. 31, 2019
Accounting for Income Taxes	Accounting for Income Taxes Our provision for income taxes was $8.8 million and $2.9 million for the three months ended March 31, 2019 and 2018 , respectively, representing effective tax rates of 10.4% and 2.9% , respectively. Our effective tax rate differs from the statutory federal income tax rate of 21% for the three months ended March 31, 2019 and 2018 , respectively, mainly as a result of the recognition of excess tax benefits related to stock-based compensation and certain foreign earnings, primarily from the Netherlands and Costa Rica, being taxed at lower tax rates. The increase in effective tax rate for the three months ended March 31, 2019 compared to the same period in 2018 is primarily attributable to reduction in excess tax benefits related to stock-based compensation resulting from the unfavorable tax impact of IRS Notice 2018-68 issued in August 2018, which limited our officers’ stock compensation deductions. For the three months ended March 31, 2019 and 2018 , we recognized excess tax benefits of $11.9 million and $23.3 million , respectively, in our provision for income taxes. We exercise significant judgment in regards to estimates of future market growth, forecasted earnings and projected taxable income in determining the provision for income taxes and for purposes of assessing our ability to utilize any future benefit from deferred tax assets. We file U.S. federal, U.S. state, and non-U.S. income tax returns. Our major tax jurisdictions include U.S. federal, the State of California and the Netherlands. For U.S. federal and state tax returns, we are no longer subject to tax examinations for years before 2015 . We are currently under examination by the IRS for tax years 2015 and 2016. With few exceptions, we are no longer subject to examination by foreign tax authorities for years before 2010 . Our total gross unrecognized tax benefits, excluding interest and penalties, was $38.0 million and $33.3 million as of March 31, 2019 and December 31, 2018 , respectively, a material amount of which would impact our effective tax rate if recognized. Our total interest and penalties accrued as of March 31, 2019 was no t material. We have elected to recognize interest and penalties related to unrecognized tax benefits as a component of income taxes. The timing and resolution of income tax examinations is uncertain, and the amounts ultimately paid, if any, upon resolution of issues raised by the taxing authorities may differ materially from the amounts accrued for each year. Although it is possible that our balance of gross unrecognized tax benefits could materially change in the next 12 months, given the uncertainty in the development of ongoing income tax examinations, we are unable to estimate the full range of possible adjustments to this balance. As of December 31, 2018 , undistributed earnings of the Company’s foreign subsidiaries totaled $533.5 million . As a result of the TCJA, during the year ended December 31, 2017, we provided for U.S. income taxes on undistributed foreign earnings through December 31, 2017, and we have reassessed our capital needs and investment strategy with regard to the indefinite reinvestment, determining that certain of those are no longer indefinitely reinvested. Of the total undistributed foreign earnings as of December 31, 2018, the amount that is not indefinitely reinvested is $239.2 million . The remaining amount of undistributed foreign earnings of approximately $294.3 million continues to be indefinitely reinvested in our international operations. Since U.S. income taxes have already been provided under the GILTI provisions of the TCJA, the additional tax impact of the distribution of such foreign earnings to the U.S. parent company would be limited to withholding taxes and is not significant. In June 2017, the Costa Rica Ministry of Foreign Trade, an agency of the Government of Costa Rica, granted an extension of certain income tax incentives for an additional twelve year period. Under these incentives, all of the income in Costa Rica is subject to a reduced tax rate. In order to receive the benefit of these incentives, we must hire specified numbers of employees and maintain certain minimum levels of fixed asset investment in Costa Rica. If we do not fulfill these conditions for any reason, our incentive could lapse and our income in Costa Rica would be subject to taxation at higher rates which could have a negative impact on our operating results. The Costa Rica corporate income tax rate that would apply, absent the incentives, is 30%

Net Income Per Share

Net Income Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Income Per Share	Net Income per Share Basic net income per share is computed using the weighted average number of shares of common stock outstanding during the period. Diluted net income per share is computed using the weighted average number of shares of common stock, adjusted for any dilutive effect of potential common stock. Potential common stock, computed using the treasury stock method, includes RSUs, MSUs, stock options and our ESPP. The following table sets forth the computation of basic and diluted net income per share attributable to common stock (in thousands, except per share amounts): Three Months Ended 2019 2018 Numerator: Net income $ 71,848 $ 95,866 Denominator: Weighted average common shares outstanding, basic 79,860 80,036 Dilutive effect of potential common stock 827 1,592 Total shares, diluted 80,687 81,628 Net income per share, basic $ 0.90 $ 1.20 Net income per share, diluted $ 0.89 $ 1.17 For the three months ended March 31, 2019 and 2018

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2019
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The supplemental cash flow information consists of the following (in thousands): Three Months Ended 2019 2018 Non-cash investing and financing activities: Fixed assets acquired with accounts payable or accrued liabilities $ 13,113 $ 18,739 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 3,820 $ — Financing cash flows from finance leases $ 2,190 $ — Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 15,984 $ — Finance leases $ 51,064 $ —

Segments and Geographical Infor

Segments and Geographical Information	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Segments and Geographical Information	Segments and Geographical Information Segment Information Operating segments are defined as components of an enterprise for which separate financial information is available that is evaluated regularly by the Chief Operating Decision Maker (“CODM”), or decision-making group, in deciding how to allocate resources and in assessing performance. Our CODM is our Chief Executive Officer. We report segment information based on the management approach. The management approach designates the internal reporting used by CODM for decision making and performance assessment as the basis for determining our reportable segments. The performance measures of our reportable segments include net revenues, gross profit and income from operations. Income from operations for each segment includes all geographic revenues, related cost of net revenues and operating expenses directly attributable to the segment. Certain operating expenses are attributable to operating segments and each allocation is measured differently based on the specific facts and circumstances of the costs being allocated. Costs not specifically allocated to segment income from operations include various corporate expenses such as stock-based compensation and costs related to IT, facilities, human resources, accounting and finance, legal and regulatory, and other separately managed general and administrative costs outside the operating segments. We group our operations into two reportable segments: Clear Aligner segment and Scanner segment. • Our Clear Aligner segment consists of Comprehensive Products, Non-Comprehensive Products and Non-Case revenues as defined below: • Comprehensive Products include, but not limited to, our Invisalign Comprehensive (formerly known as Invisalign Full and Invisalign Teen), Invisalign Assist and Invisalign First. • Non-Comprehensive Products include, Invisalign Express 10, Invisalign Express 5, Express Package, Lite Package and Invisalign Go products in addition to revenues from the sale of aligners to SDC under our supply agreement. • Non-Case includes, but not limited to, Vivera retainers along with our training and ancillary products for treating malocclusion. • Our Scanner segment consists of intraoral scanning systems, additional services and ancillary products available with the intraoral scanners that provide digital alternatives to the traditional cast models. This segment includes our iTero scanner and OrthoCAD services. These reportable operating segments are based on how our CODM views and evaluates our operations as well as allocation of resources. The following information relates to these segments (in thousands): Three Months Ended Net revenues 2019 2018 Clear Aligner $ 469,205 $ 385,505 Scanner 79,766 51,419 Total net revenues $ 548,971 $ 436,924 Gross profit Clear Aligner $ 351,358 $ 296,976 Scanner 50,738 30,432 Total gross profit $ 402,096 $ 327,408 Income from operations Clear Aligner $ 158,641 $ 161,454 Scanner 28,259 16,082 Unallocated corporate expenses (99,199 ) (79,344 ) Total income from operations $ 87,701 $ 98,192 Depreciation and amortization Clear Aligner $ 11,135 $ 6,384 Scanner 2,097 1,104 Unallocated corporate depreciation and amortization 9,446 3,946 Total depreciation and amortization $ 22,678 $ 11,434 Impairments and other charges Clear Aligner $ 29,782 $ — Scanner — — Unallocated corporate impairments and other charges — — Total impairments and other charges $ 29,782 $ — The following table reconciles total segment income from operations in the table above to net income before provision for income taxes and equity losses of investee (in thousands): Three Months Ended 2019 2018 Total segment income from operations $ 186,900 $ 177,536 Unallocated corporate expenses (99,199 ) (79,344 ) Total income from operations 87,701 98,192 Interest income 2,633 2,176 Other income (expense), net (5,746 ) 177 Net income before provision for income taxes and equity in losses of investee $ 84,588 $ 100,545 Geographical Information Net revenues are presented below by geographic area (in thousands): Three Months Ended 2019 2018 Net revenues 1 : United States $ 279,005 $ 237,103 The Netherlands 174,744 139,531 China 42,616 25,586 Other International 52,606 34,704 Total net revenues $ 548,971 $ 436,924 1 Net revenues are attributed to countries based on location of where revenues are recognized. Tangible long-lived assets are presented below by geographic area (in thousands): March 31, December 31, 2018 Long-lived assets 2 : The Netherlands $ 211,302 $ 206,679 United States 175,167 139,239 Costa Rica 82,138 80,218 China 55,676 36,249 Mexico 33,734 33,240 Other International 73,634 25,704 Total long-lived assets $ 631,651 $ 521,329 2

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Basis of presentation	Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements have been prepared by Align Technology, Inc. (“we”, “our”, or “Align”) in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”) and contains all adjustments, including normal recurring adjustments, necessary to state fairly our results of operations for the three months ended March 31, 2019 and 2018 , our comprehensive income for the three months ended March 31, 2019 and 2018 , our financial position as of March 31, 2019 , our stockholders’ equity for the three months ended March 31, 2019 and 2018, and our cash flows for the three months ended March 31, 2019 and 2018 . The Condensed Consolidated Balance Sheet as of December 31, 2018 was derived from the December 31, 2018 audited financial statements. It does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S.”). We adopted Accounting Standards Update (“ ASU”) 2016-02, “ Leases ” (Topic 842) in the first quarter of fiscal year 2019 by electing the transition method issued in ASU 2018-11 and the package of practical expedients available in the standard. The standard had a material impact on our Condensed Consolidated Balance Sheet as of March 31, 2019 as we recognized assets and liabilities related to our leases. The adoption did not have an impact to prior periods. The results of operations 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 or any other future period, and we make no representations related thereto. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” “Quantitative and Qualitative Disclosures About Market Risk” and the Consolidated Financial Statements and notes thereto included in Items 7, 7A and 8, respectively, in our Annual Report on Form 10-K for the year ended December 31, 2018
Use of estimates	Use of Estimates
Lease	Lease
Recent Accounting Pronouncements	Recent Accounting Pronouncements (i) New Accounting Updates Recently Adopted In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-02, “ Leases ” (Topic 842) to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The updated guidance is effective for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. In July 2018, the FASB issued ASU 2018-11, “ Leases-Targeted Improvements, ” which p rovides an additional transition method by allowing entities to initially apply the new leases standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings. We adopted the guidance in the first quarter of fiscal year 2019 by electing the transition method issued in ASU 2018-11 and the package of practical expedients available in the standard. The standard had a material impact on our Condensed Consolidated Balance Sheet as of March 31, 2019 as we recognized assets and liabilities related to our leases. The adoption did not have an impact to prior periods. In February 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 the tax effects resulting from the U.S. Tax Cuts and Jobs Act (the “TCJA”) related to items in accumulated other comprehensive income. The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2018 on a retrospective basis and early adoption is permitted. We adopted the standard in the first quarter of fiscal year 2019 which did not have a material impact on our consolidated financial statements and related disclosures. The TCJA did not affect our accumulated other comprehensive income (loss), net, and therefore we did not reclassify any income tax effects from accumulated other comprehensive income (loss), net to our retained earnings. (ii) Recent Accounting Updates Not Yet Effective In June 2016, the FASB issued ASU 2016-13, “ Financial Instruments - Credit Losses ” (Topic 326) . The FASB issued this update to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments in this update replace the existing guidance of incurred loss impairment methodology with an approach that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. In November 2018, the FASB issued ASU 2018-19, “ Codification Improvements to Topic 326, Financial Instruments - Credit Losses ” which clarifies the scope of guidance in the ASU 2016-13 . The updated guidance is effective for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption of the update is permitted in fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU 2017-04, “Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” to simplify the subsequent measurement of goodwill by eliminating step two from the goodwill impairment test. Under the amendments, an entity will recognize an impairment charge for the amount by which the carrying value exceeds the fair value. The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2019 on a prospective basis and early adoption is permitted. We are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, “ Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement,” to modify the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement . The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2019 on a prospective basis and early adoption is permitted. We are currently evaluating the impact of this guidance on our related disclosures. In August 2018, the FASB issued ASU 2018-15, “ Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract,” to clarify the guidance on the costs of implementing a cloud computing hosting arrangement that is a service contract. Under the amendments, the entity is required to follow the guidance in Subtopic 350-40, Internal-Use Software

Investments and Fair Value Me_2

Investments and Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Short-Term And Long-Term Marketable Securities	As of March 31, 2019 and December 31, 2018 , the estimated fair value of our short-term and long-term marketable securities, classified as available for sale, are as follows (in thousands): Short-term March 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 38,234 $ — $ — $ 38,234 Corporate bonds 33,240 8 (2 ) 33,246 U.S. government agency bonds 14,253 — (31 ) 14,222 U.S. government treasury bonds 45,854 7 (3 ) 45,858 Foreign bonds 12,960 3 (3 ) 12,960 Certificates of deposit 20 — — 20 Total marketable securities, short-term $ 144,561 $ 18 $ (39 ) $ 144,540 There are no long-term marketable securities as of March 31, 2019. Short-term December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 17,793 $ — $ — $ 17,793 Corporate bonds 45,100 — (48 ) 45,052 U.S. government agency bonds 19,981 — (77 ) 19,904 U.S. government treasury bonds 15,292 — (1 ) 15,291 Certificates of deposit 420 1 (1 ) 420 Total marketable securities, short-term $ 98,586 $ 1 $ (127 ) $ 98,460 Long-term December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Corporate bonds $ 4,957 $ 5 $ (2 ) $ 4,960 U.S. government agency bonds 1,399 8 — 1,407 U.S. government treasury bonds 2,235 9 — 2,244 Certificates of deposit 500 1 — 501 Total marketable securities, long-term $ 9,091 $ 23 $ (2 ) $ 9,112
Investments Classified by Contractual Maturity Date	As the carrying value approximates the fair value for our short-term and long-term marketable securities shown in the tables above, the following table summarizes the fair value of our short-term and long-term marketable securities classified by contractual maturity as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, One year or less $ 144,540 $ 98,460 Due in greater than one year — 9,112 Total available for sale short-term and long-term marketable securities $ 144,540 $ 107,572
Investments in privately held companies	Our investments in privately held companies as of March 31, 2019 and December 31, 2018 are as follows (in thousands): March 31, December 31, Equity securities under the equity method investment 1 $ 41,969 $ 45,913 Equity securities without readily determinable fair values 2 $ 5,887 $ 9,862 1 Refer to Note 5 “Equity Method Investments” of the Notes to Condensed Consolidated Financial Statements for more information 2 The equity securities are reported as a nonrecurring investment within other assets in our Condensed Consolidated Balance Sheet. During the three months ended March 31, 2019 , there was approximately $4.0 million
Financial Assets Measured At Fair Value On Recurring Basis	The following tables summarize our financial assets measured at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 (in thousands): Description Balance as of March 31, 2019 Level 1 Level 2 Cash equivalents: Money market funds $ 369,896 $ 369,896 $ — Commercial paper 7,978 — 7,978 Corporate bonds 6,809 — 6,809 Short-term investments: Commercial paper 38,234 — 38,234 Corporate bonds 33,246 — 33,246 U.S. government treasury bonds 45,858 45,858 — U.S. government agency bonds 14,222 — 14,222 Foreign bonds 12,960 — 12,960 Certificates of deposit 20 — 20 Prepaid expenses and other current assets: Israeli funds 3,031 — 3,031 $ 532,254 $ 415,754 $ 116,500 Description Balance as of December 31, 2018 Level 1 Level 2 Cash equivalents: Money market funds $ 431,081 $ 431,081 $ — Commercial paper 4,681 — 4,681 U.S. government treasury bonds 2,195 2,195 — Corporate bonds 3,880 — 3,880 Short-term investments: Commercial paper 17,793 — 17,793 Corporate bonds 45,052 — 45,052 U.S. government agency bonds 19,904 — 19,904 U.S. government treasury bonds 15,291 15,291 — Certificates of deposit 420 — 420 Long-term investments: U.S. government agency bonds 1,407 — 1,407 Corporate bonds 4,960 — 4,960 U.S. government treasury bonds 2,244 2,244 — Certificates of deposit 501 — 501 Prepaid expenses and other current assets: Israeli funds 3,047 — 3,047 $ 552,456 $ 450,811 $ 101,645
Notional value of derivative instruments	The following table presents the gross notional value of all our foreign exchange forward contracts outstanding as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 Local Currency Amount Notional Contract Amount (USD) Euro €73,000 $ 82,059 Chinese Yuan ¥540,000 80,380 Canadian Dollar C$33,500 25,105 British Pound £16,500 21,508 Japanese Yen ¥2,100,000 18,962 Brazilian Real R$69,000 17,660 Mexican Peso M$115,000 5,942 Australian Dollar A$3,000 2,128 $ 253,744

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Schedule of Inventories	Inventories consist of the following (in thousands): March 31, December 31, Raw materials $ 29,002 $ 26,119 Work in process 19,710 13,784 Finished goods 19,777 15,738 Total inventories $ 68,489 $ 55,641
Schedule of Other Assets	Other assets consist of the following (in thousands): March 31, December 31, Capitalized commissions $ 10,747 $ 9,185 Equity securities 5,887 9,862 Security deposits 5,038 5,162 Other long-term assets 4,514 2,778 Total other assets $ 26,186 $ 26,987
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): March 31, December 31, Accrued payroll and benefits $ 87,603 $ 127,109 Accrued expenses 44,343 39,323 Deferred litigation settlement gain 35,000 — Accrued customer credits and deposits 18,094 12,439 Current operating lease liabilities 15,592 — Accrued warranty 10,233 8,551 Accrued property, plant and equipment 9,901 8,193 Accrued sales return reserve 8,202 6,534 Accrued sales rebate 6,612 5,668 Accrued sales tax and value added tax 5,893 6,276 Accrued professional fees 4,955 6,752 Accrued income taxes 2,255 5,752 Other accrued liabilities 4,071 8,082 Total accrued liabilities $ 252,754 $ 234,679
Schedule of Warranty Accrual	Warranty accrual as of March 31, 2019 and 2018 consists of the following activity (in thousands): Three Months Ended 2019 2018 Balance at beginning of period $ 8,551 $ 5,929 Charged to cost of revenues 3,133 2,359 Actual warranty expenditures (1,451 ) (1,631 ) Balance at end of period $ 10,233 $ 6,657
Schedule of Deferred Revenues	Deferred revenues consist of the following (in thousands): March 31, December 31, Deferred revenues - current $ 433,518 $ 393,138 Deferred revenues - long-term 1 19,166 17,051 1 Included in other long-term liabilities within our Condensed Consolidated Balance Sheets

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Assets And Liabilities, Lessee	The supplemental balance sheet information consists of following (in thousands): Leases March 31, Operating leases: Operating lease right-of-use assets 1 $ 56,384 Accrued liabilities $ 15,592 Operating lease liabilities 59,307 Total operating lease liabilities $ 74,899 Finance leases: Property, plant and equipment, net $ 50,655 Finance lease liabilities $ 56,100 1 The balance is net of impairment charges recorded in the first quarter of 2019. Refer to Note 8“Impairments and Other Charges” of the Notes to Condensed Consolidated Financial Statements for more information
Lease, Cost	The components of lease expenses consists of following (in thousands): Lease Cost Three Months Ended Operating lease cost 1 $ 5,301 Finance lease cost: Amortization of leased assets 1 $ 409 Interest on lease liabilities 2 392 Total finance lease cost $ 801 1 Included in operating expenses on our Condensed Consolidated Statement of Operations 2
Lessee, Operating Lease, Disclosure	Remaining Lease Term and Discount Rate March 31, Weighted average remaining lease term (in years) Operating leases 5.8 Finance leases 1 0 Weighted average discount rate Operating leases 4.7 % Finance leases 4.2 % 1 On April 5, 2019, we paid the balance of the $56.0 million purchase price and closed the Purchase and Sale Agreement. Refer to Note 10“Commitments and Contingencies” of the Notes to Condensed Consolidated Financial Statements
Finance Lease, Liability, Maturity	Maturities of operating lease liabilities as of March 31, 2019 are as follows (in thousands): Fiscal Year Ending December 31, Operating Leases Finance Leases Remainder of 2019 $ 15,709 $ 56,100 2020 18,148 — 2021 16,398 — 2022 11,915 — 2023 8,899 — Thereafter 13,302 — Total lease payments $ 84,371 $ 56,100 Less: Interest (9,472 ) — Total lease liabilities $ 74,899 $ 56,100
Lessee, Operating Lease, Liability, Maturity	Maturities of operating lease liabilities as of March 31, 2019 are as follows (in thousands): Fiscal Year Ending December 31, Operating Leases Finance Leases Remainder of 2019 $ 15,709 $ 56,100 2020 18,148 — 2021 16,398 — 2022 11,915 — 2023 8,899 — Thereafter 13,302 — Total lease payments $ 84,371 $ 56,100 Less: Interest (9,472 ) — Total lease liabilities $ 74,899 $ 56,100
Schedule of Future Lease Payments	Minimum future lease payments previously disclosed under ASC 840 in our Annual Report on Form 10-K for the year ended December 31, 2018 (in thousands) are as follows: Fiscal Year Ending December 31, Operating Leases 2019 $ 21,429 2020 20,483 2021 18,897 2022 15,096 2023 12,400 Thereafter 18,371 Total minimum lease payments $ 106,676

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Summary of Goodwill by Reportable Segment	The change in the carrying value of goodwill for the three months ended March 31, 2019 , all attributable to our Clear Aligner reporting unit, is as follows (in thousands): Total Balance as of December 31, 2018 $ 64,029 Adjustments 1 (22 ) Balance as of March 31, 2019 $ 64,007 1 The adjustments to goodwill during the period were a result of foreign currency translation
Schedule of Amortized Intangible Assets	Acquired intangible long-lived assets are being amortized as follows (in thousands): Weighted Average Amortization Period (in years) Gross Carrying Amount as of March 31, 2019 Accumulated Amortization Accumulated Impairment Loss Net Carrying Trademarks 15 $ 7,100 $ (1,942 ) $ (4,179 ) $ 979 Existing technology 13 12,600 (5,408 ) (4,328 ) 2,864 Customer relationships 11 33,500 (17,008 ) (10,751 ) 5,741 Reacquired rights 3 7,500 (5,066 ) — 2,434 Patents 8 6,796 (2,542 ) — 4,254 Other 2 618 (568 ) — 50 Total intangible assets $ 68,114 $ (32,534 ) $ (19,258 ) $ 16,322 Weighted Average Amortization Period (in years) Gross Carrying Amount as of December 31, 2018 Accumulated Amortization Accumulated Impairment Loss Net Carrying Value as of December 31, 2018 Trademarks 15 $ 7,100 $ (1,907 ) $ (4,179 ) $ 1,014 Existing technology 13 12,600 (5,268 ) (4,328 ) 3,004 Customer relationships 11 33,500 (16,542 ) (10,751 ) 6,207 Reacquired rights 3 7,500 (4,341 ) — 3,159 Patents 8 6,796 (2,334 ) — 4,462 Other 2 618 (544 ) — 74 Total intangible assets $ 68,114 $ (30,936 ) $ (19,258 ) $ 17,920
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The total estimated annual future amortization expense for these acquired intangible assets as of March 31, 2019 is as follows (in thousands): Fiscal Year Ending December 31, Amortization Remainder of 2019 $ 4,544 2020 3,838 2021 3,389 2022 2,116 2023 1,495 Thereafter 940 Total $ 16,322

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Stock-based Compensation Expense	The stock-based compensation related to all of our stock-based awards and employee stock purchases for the three months ended March 31, 2019 and 2018 is as follows (in thousands): Three Months Ended 2019 2018 Cost of net revenues $ 1,112 $ 881 Selling, general and administrative 16,890 12,578 Research and development 3,042 2,371 Total stock-based compensation $ 21,044 $ 15,830
Summary Of Restricted Stock Units	A summary for the three months ended March 31, 2019 is as follows: Number of Shares Underlying RSUs (in thousands) Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Nonvested as of December 31, 2018 931 $ 129.39 Granted 255 253.84 Vested and released (356 ) 95.18 Forfeited (20 ) 155.77 Nonvested as of March 31, 2019 810 $ 183.06 1.67 $ 230,206
Summary Of Market-performance Based Restricted Stock Units	The following table summarizes the MSU performance for the three months ended March 31, 2019 : Number of Shares Underlying MSUs (in thousands) Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Nonvested as of December 31, 2018 324 $ 215.07 Granted 133 245.69 Vested and released (179 ) 72.74 Forfeited (5 ) 265.42 Nonvested as of March 31, 2019 273 $ 322.53 1.84 $ 77,513
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions	The fair value of the option component of the 2010 Purchase Plan shares was estimated at the grant date using the Black-Scholes option pricing model with the following weighted average assumptions: Three Months Ended 2019 2018 Expected term (in years) 1.4 1.3 Expected volatility 48.6 % 35.7 % Risk-free interest rate 2.5 % 1.9 % Expected dividends — — Weighted average fair value at grant date $ 90.36 $ 78.38

Net Income Per Share (Tables)

Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule Of Earnings Per Share Basic And Diluted	The following table sets forth the computation of basic and diluted net income per share attributable to common stock (in thousands, except per share amounts): Three Months Ended 2019 2018 Numerator: Net income $ 71,848 $ 95,866 Denominator: Weighted average common shares outstanding, basic 79,860 80,036 Dilutive effect of potential common stock 827 1,592 Total shares, diluted 80,687 81,628 Net income per share, basic $ 0.90 $ 1.20 Net income per share, diluted $ 0.89 $ 1.17

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2019
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	The supplemental cash flow information consists of the following (in thousands): Three Months Ended 2019 2018 Non-cash investing and financing activities: Fixed assets acquired with accounts payable or accrued liabilities $ 13,113 $ 18,739 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 3,820 $ — Financing cash flows from finance leases $ 2,190 $ — Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 15,984 $ — Finance leases $ 51,064 $ —

Segments and Geographical Inf_2

Segments and Geographical Information (Tables)	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Schedule of Segment Reporting Information, by Segment	These reportable operating segments are based on how our CODM views and evaluates our operations as well as allocation of resources. The following information relates to these segments (in thousands): Three Months Ended Net revenues 2019 2018 Clear Aligner $ 469,205 $ 385,505 Scanner 79,766 51,419 Total net revenues $ 548,971 $ 436,924 Gross profit Clear Aligner $ 351,358 $ 296,976 Scanner 50,738 30,432 Total gross profit $ 402,096 $ 327,408 Income from operations Clear Aligner $ 158,641 $ 161,454 Scanner 28,259 16,082 Unallocated corporate expenses (99,199 ) (79,344 ) Total income from operations $ 87,701 $ 98,192 Depreciation and amortization Clear Aligner $ 11,135 $ 6,384 Scanner 2,097 1,104 Unallocated corporate depreciation and amortization 9,446 3,946 Total depreciation and amortization $ 22,678 $ 11,434 Impairments and other charges Clear Aligner $ 29,782 $ — Scanner — — Unallocated corporate impairments and other charges — — Total impairments and other charges $ 29,782 $ — The following table reconciles total segment income from operations in the table above to net income before provision for income taxes and equity losses of investee (in thousands): Three Months Ended 2019 2018 Total segment income from operations $ 186,900 $ 177,536 Unallocated corporate expenses (99,199 ) (79,344 ) Total income from operations 87,701 98,192 Interest income 2,633 2,176 Other income (expense), net (5,746 ) 177 Net income before provision for income taxes and equity in losses of investee $ 84,588 $ 100,545
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas	Net revenues are presented below by geographic area (in thousands): Three Months Ended 2019 2018 Net revenues 1 : United States $ 279,005 $ 237,103 The Netherlands 174,744 139,531 China 42,616 25,586 Other International 52,606 34,704 Total net revenues $ 548,971 $ 436,924 1 Net revenues are attributed to countries based on location of where revenues are recognized. Tangible long-lived assets are presented below by geographic area (in thousands): March 31, December 31, 2018 Long-lived assets 2 : The Netherlands $ 211,302 $ 206,679 United States 175,167 139,239 Costa Rica 82,138 80,218 China 55,676 36,249 Mexico 33,734 33,240 Other International 73,634 25,704 Total long-lived assets $ 631,651 $ 521,329 2

Investments and Fair Value Me_3

Investments and Fair Value Measurements Short-Term and Long-Term Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Total available for sale short-term and long-term marketable securities	$ 144,540	$ 107,572
Fair Value, Measurements, Recurring | Short-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	144,561	98,586
Gross Unrealized Gains	18	1
Gross Unrealized Losses	(39)	(127)
Total available for sale short-term and long-term marketable securities	144,540	98,460
Fair Value, Measurements, Recurring | Short-term Investments | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	38,234	17,793
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total available for sale short-term and long-term marketable securities	38,234	17,793
Fair Value, Measurements, Recurring | Short-term Investments | Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	33,240	45,100
Gross Unrealized Gains	8	0
Gross Unrealized Losses	(2)	(48)
Total available for sale short-term and long-term marketable securities	33,246	45,052
Fair Value, Measurements, Recurring | Short-term Investments | U.S. government agency bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,253	19,981
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(31)	(77)
Total available for sale short-term and long-term marketable securities	14,222	19,904
Fair Value, Measurements, Recurring | Short-term Investments | U.S. government treasury bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	45,854	15,292
Gross Unrealized Gains	7	0
Gross Unrealized Losses	(3)	(1)
Total available for sale short-term and long-term marketable securities	45,858	15,291
Fair Value, Measurements, Recurring | Short-term Investments | Foreign bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,960
Gross Unrealized Gains	3
Gross Unrealized Losses	(3)
Total available for sale short-term and long-term marketable securities	12,960
Fair Value, Measurements, Recurring | Short-term Investments | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20	420
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	(1)
Total available for sale short-term and long-term marketable securities	$ 20	420
Fair Value, Measurements, Recurring | Long-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		9,091
Gross Unrealized Gains		23
Gross Unrealized Losses		(2)
Total available for sale short-term and long-term marketable securities		9,112
Fair Value, Measurements, Recurring | Long-term Investments | Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		4,957
Gross Unrealized Gains		5
Gross Unrealized Losses		(2)
Total available for sale short-term and long-term marketable securities		4,960
Fair Value, Measurements, Recurring | Long-term Investments | U.S. government agency bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		1,399
Gross Unrealized Gains		8
Gross Unrealized Losses		0
Total available for sale short-term and long-term marketable securities		1,407
Fair Value, Measurements, Recurring | Long-term Investments | U.S. government treasury bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,235
Gross Unrealized Gains		9
Gross Unrealized Losses		0
Total available for sale short-term and long-term marketable securities		2,244
Fair Value, Measurements, Recurring | Long-term Investments | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		500
Gross Unrealized Gains		1
Gross Unrealized Losses		0
Total available for sale short-term and long-term marketable securities		$ 501

Investments and Fair Value Me_4

Investments and Fair Value Measurements Additional Information (Details)	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Original maturity of highly liquid investments included in cash and cash equivalents			40 months
Weighted average maturity	5 months	4 months

Investments and Fair Value Me_5

Investments and Fair Value Measurements Available For Sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
One year or less	$ 144,540	$ 98,460
Due in greater than one year	0	9,112
Total available for sale short-term and long-term marketable securities	$ 144,540	$ 107,572

Investments and Fair Value Me_6

Investments and Fair Value Measurements Investments in Privately Held Companies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Equity securities without readily determinable fair values	$ 5,887		$ 9,862
Schedule of Available-for-sale Securities [Line Items]
Equity method investments	41,969		0
Equity method investments	0		$ 45,913
Impairment on equity investment	$ 3,975	$ 0

Investments and Fair Value Me_7

Investments and Fair Value Measurements Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	$ 144,540,000	$ 107,572,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	532,254,000	552,456,000
Fair Value, Measurements, Recurring | Israeli funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	3,031,000	3,047,000
Fair Value, Measurements, Recurring | Cash Equivalents | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	369,896,000	431,081,000
Fair Value, Measurements, Recurring | Cash Equivalents | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	7,978,000	4,681,000
Fair Value, Measurements, Recurring | Cash Equivalents | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	6,809,000	3,880,000
Fair Value, Measurements, Recurring | Cash Equivalents | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		2,195,000
Fair Value, Measurements, Recurring | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	144,540,000	98,460,000
Fair Value, Measurements, Recurring | Short-term Investments | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	38,234,000	17,793,000
Fair Value, Measurements, Recurring | Short-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	33,246,000	45,052,000
Fair Value, Measurements, Recurring | Short-term Investments | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	45,858,000	15,291,000
Fair Value, Measurements, Recurring | Short-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	14,222,000	19,904,000
Fair Value, Measurements, Recurring | Short-term Investments | Foreign bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	12,960,000
Fair Value, Measurements, Recurring | Short-term Investments | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	20,000	420,000
Fair Value, Measurements, Recurring | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		9,112,000
Fair Value, Measurements, Recurring | Long-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		4,960,000
Fair Value, Measurements, Recurring | Long-term Investments | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		2,244,000
Fair Value, Measurements, Recurring | Long-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		1,407,000
Fair Value, Measurements, Recurring | Long-term Investments | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		501,000
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	415,754,000	450,811,000
Fair Value, Measurements, Recurring | Level 1 | Israeli funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	0	0
Fair Value, Measurements, Recurring | Level 1 | Cash Equivalents | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	369,896,000	431,081,000
Fair Value, Measurements, Recurring | Level 1 | Cash Equivalents | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring | Level 1 | Cash Equivalents | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring | Level 1 | Cash Equivalents | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		2,195,000
Fair Value, Measurements, Recurring | Level 1 | Short-term Investments | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Level 1 | Short-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Level 1 | Short-term Investments | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	45,858,000	15,291,000
Fair Value, Measurements, Recurring | Level 1 | Short-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Level 1 | Short-term Investments | Foreign bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0
Fair Value, Measurements, Recurring | Level 1 | Short-term Investments | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Level 1 | Long-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		0
Fair Value, Measurements, Recurring | Level 1 | Long-term Investments | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		2,244,000
Fair Value, Measurements, Recurring | Level 1 | Long-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		0
Fair Value, Measurements, Recurring | Level 1 | Long-term Investments | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	116,500,000	101,645,000
Fair Value, Measurements, Recurring | Level 2 | Israeli funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	3,031,000	3,047,000
Fair Value, Measurements, Recurring | Level 2 | Cash Equivalents | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring | Level 2 | Cash Equivalents | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	7,978,000	4,681,000
Fair Value, Measurements, Recurring | Level 2 | Cash Equivalents | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	6,809,000	3,880,000
Fair Value, Measurements, Recurring | Level 2 | Cash Equivalents | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Fair Value, Measurements, Recurring | Level 2 | Short-term Investments | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	38,234,000	17,793,000
Fair Value, Measurements, Recurring | Level 2 | Short-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	33,246,000	45,052,000
Fair Value, Measurements, Recurring | Level 2 | Short-term Investments | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Level 2 | Short-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	14,222,000	19,904,000
Fair Value, Measurements, Recurring | Level 2 | Short-term Investments | Foreign bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	12,960,000
Fair Value, Measurements, Recurring | Level 2 | Short-term Investments | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	$ 20,000	420,000
Fair Value, Measurements, Recurring | Level 2 | Long-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		4,960,000
Fair Value, Measurements, Recurring | Level 2 | Long-term Investments | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		0
Fair Value, Measurements, Recurring | Level 2 | Long-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		1,407,000
Fair Value, Measurements, Recurring | Level 2 | Long-term Investments | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments		$ 501,000

Investments and Fair Value Me_8

Investments and Fair Value Measurements Derivative Notional Instruments (Details) - Level 2 - Israeli funds - Foreign Exchange Forward € in Thousands, ¥ in Thousands, ¥ in Thousands, £ in Thousands, R$ in Thousands, $ in Thousands, $ in Thousands, $ in Thousands, $ in Thousands

Mar. 31, 2019EUR (€)

Mar. 31, 2019CNY (¥)

Mar. 31, 2019USD ($)

Mar. 31, 2019JPY (¥)

Mar. 31, 2019AUD ($)

Mar. 31, 2019GBP (£)

Mar. 31, 2019CAD ($)

Mar. 31, 2019MXN ($)

Mar. 31, 2019BRL (R$)

Dec. 31, 2018EUR (€)

Dec. 31, 2018CNY (¥)

Dec. 31, 2018USD ($)

Dec. 31, 2018JPY (¥)

Dec. 31, 2018AUD ($)

Dec. 31, 2018GBP (£)

Dec. 31, 2018CAD ($)

Dec. 31, 2018BRL (R$)

Derivative [Line Items]

Notional amount

$ 253,744

$ 200,382

Euro

Derivative [Line Items]

Notional amount

€ 73,000

82,059

€ 62,000

71,095

Chinese Yuan

Derivative [Line Items]

Notional amount

¥ 540,000

80,380

¥ 375,000

54,515

Canadian Dollar

Derivative [Line Items]

Notional amount

25,105

$ 33,500

19,808

$ 27,000

British Pound

Derivative [Line Items]

Notional amount

21,508

£ 16,500

16,635

£ 13,000

Japanese Yen

Derivative [Line Items]

Notional amount

18,962

¥ 2,100,000

15,357

¥ 1,700,000

Brazilian Real

Derivative [Line Items]

Notional amount

17,660

R$ 69000

20,858

R$ 81000

Mexican Peso

Derivative [Line Items]

Notional amount

5,942

$ 115,000

Australian Dollar

Derivative [Line Items]

Notional amount

$ 2,128

$ 3,000

$ 2,114

$ 3,000

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Disclosure Inventories [Abstract]
Document Period End Date	Mar. 31, 2019
Raw materials	$ 29,002	$ 26,119
Work in process	19,710	13,784
Finished goods	19,777	15,738
Total inventories	$ 68,489	$ 55,641

Balance Sheet Components Other

Balance Sheet Components Other Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Notes To Financial Statements [Abstract]
Document Period End Date	Mar. 31, 2019
Capitalized commissions	$ 10,747	$ 9,185
Equity securities	5,887	9,862
Security deposits	5,038	5,162
Other long-term assets	4,514	2,778
Total other assets	$ 26,186	$ 26,987

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Disclosure Accrued Liabilities [Abstract]
Accrued payroll and benefits	$ 87,603	$ 127,109
Accrued expenses	44,343	39,323
Deferred litigation settlement gain	35,000	0
Accrued customer credits and deposits	18,094	12,439
Current operating lease liabilities	15,592	0
Accrued warranty	10,233	8,551
Accrued property, plant and equipment	9,901	8,193
Accrued sales return reserve	8,202	6,534
Accrued sales rebate	6,612	5,668
Accrued sales tax and value added tax	5,893	6,276
Accrued professional fees	4,955	6,752
Accrued income taxes	2,255	5,752
Other accrued liabilities	4,071	8,082
Total accrued liabilities	$ 252,754	$ 234,679

Warranty Accrual Activity (Deta

Warranty Accrual Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 8,551	$ 5,929
Charged to cost of revenues	3,133	2,359
Actual warranty expenditures	(1,451)	(1,631)
Balance at end of period	$ 10,233	$ 6,657

Balance Sheet Components Deferr

Balance Sheet Components Deferred Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Notes To Financial Statements [Abstract]
Document Period End Date	Mar. 31, 2019
Deferred revenues - current	$ 433,518	$ 393,138
Deferred revenues - long-term	$ 19,166	$ 17,051

Balance Sheet Components Narrat

Balance Sheet Components Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Balance Sheet Statements, Captions [Line Items]
Document Period End Date	Mar. 31, 2019
Revenue recognized	$ 548,971	$ 436,924
Revenue, remaining performance obligation	483,800
Deferred Revenue
Condensed Balance Sheet Statements, Captions [Line Items]
Deferred revenue	$ 68,400	$ 47,300
Minimum
Condensed Balance Sheet Statements, Captions [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Maximum
Condensed Balance Sheet Statements, Captions [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	5 years

Leases (Details)

Leases (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Lessee, Lease, Description [Line Items]
Lease not yet commenced, amount	$ 9.2
Minimum
Lessee, Lease, Description [Line Items]
Term of contract	3 years
Maximum
Lessee, Lease, Description [Line Items]
Term of contract	5 years

Leases - Lease Assets and Liabi

Leases - Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Operating leases:
Operating lease right-of-use assets	$ 56,384	$ 0
Accrued liabilities	15,592	0
Operating lease liabilities	59,307	$ 0
Total operating lease liabilities	74,899
Finance leases:
Property, plant and equipment, net	50,655
Finance lease liabilities	$ 56,100

Leases - Schedule of Lease Cost

Leases - Schedule of Lease Cost (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating Lease, Cost	$ 5,301
Finance Lease, Right-of-Use Asset, Amortization	409
Finance Lease, Interest Expense	392
Finance Lease, Cost	$ 801

Leases - Remaining Lease Term a

Leases - Remaining Lease Term and Discount Rate (Details) - USD ($) $ in Thousands	Apr. 05, 2019	Mar. 31, 2019	Mar. 31, 2018
Lessee, Lease, Description [Line Items]
Financing cash flows from finance leases		$ 2,190	$ 0
Weighted average remaining lease term (in years)
Operating leases		5 years 9 months 18 days
Finance leases1		0 years
Weighted average discount rate
Operating leases		4.70%
Finance leases		4.20%
Subsequent Event
Lessee, Lease, Description [Line Items]
Financing cash flows from finance leases	$ 56,000

Leases - Maturities of Operatin

Leases - Maturities of Operating Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019USD ($)
Operating Leases
Remainder of 2019	$ 15,709
2020	18,148
2021	16,398
2022	11,915
2023	8,899
Thereafter	13,302
Total lease payments	84,371
Less: Interest	(9,472)
Total lease liabilities	74,899
Finance Leases
Remainder of 2019	56,100
2020	0
2021	0
2022	0
2023	0
Thereafter	0
Total lease payments	56,100
Total lease liabilities	0
Total lease liabilities	$ 56,100

Leases - Minimum Future Lease P

Leases - Minimum Future Lease Payments Previously Disclosed under ASC 840 (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 21,429
2020	20,483
2021	18,897
2022	15,096
2023	12,400
Thereafter	18,371
Total minimum lease payments	$ 106,676

Equity Method Investments (Deta

Equity Method Investments (Details) - USD ($) $ in Thousands	Feb. 07, 2018	Jul. 24, 2017	Jul. 25, 2016	Jun. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Apr. 30, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Equity method investments					$ 42,000			$ 45,900
Net revenues					548,971	$ 436,924
Loan repayment from equity investee					0	30,000
SDC
Schedule of Equity Method Investments [Line Items]
Ownership			17.00%
Payments to acquire		$ 12,800	$ 46,700
Additional ownership acquired		2.00%
Due from related parties					18,000			$ 16,300
Net revenues					$ 5,700	$ 5,300
SDC
Schedule of Equity Method Investments [Line Items]
Loan repayment from equity investee	$ 30,000
Maximum | SDC
Schedule of Equity Method Investments [Line Items]
Loan receivable		$ 30,000
Short-term notes receivable | Subsequent Event | SDC
Schedule of Equity Method Investments [Line Items]
Note receivable							$ 54,200
Scenario, Forecast | Subsequent Event | SDC
Schedule of Equity Method Investments [Line Items]
Equity method investment, gain				$ 16,000

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Change in Carrying Value of Goodwill (Details) - Clear Aligner $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2018	$ 64,029
Adjustments	(22)
Balance as of March 31, 2019	$ 64,007

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, beginning balance	$ 68,114	$ 68,114
Accumulated Amortization	(32,534)	(30,936)
Accumulated Impairment Loss	(19,258)	(19,258)
Net Carrying Value, ending balance	$ 16,322	$ 17,920
Trademarks
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	15 years	15 years
Gross Carrying Amount, beginning balance	$ 7,100	$ 7,100
Accumulated Amortization	(1,942)	(1,907)
Accumulated Impairment Loss	(4,179)	(4,179)
Net Carrying Value, ending balance	$ 979	$ 1,014
Existing technology
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	13 years	13 years
Gross Carrying Amount, beginning balance	$ 12,600	$ 12,600
Accumulated Amortization	(5,408)	(5,268)
Accumulated Impairment Loss	(4,328)	(4,328)
Net Carrying Value, ending balance	$ 2,864	$ 3,004
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	11 years	11 years
Gross Carrying Amount, beginning balance	$ 33,500	$ 33,500
Accumulated Amortization	(17,008)	(16,542)
Accumulated Impairment Loss	(10,751)	(10,751)
Net Carrying Value, ending balance	$ 5,741	$ 6,207
Reacquired rights
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	3 years	3 years
Gross Carrying Amount, beginning balance	$ 7,500	$ 7,500
Accumulated Amortization	(5,066)	(4,341)
Accumulated Impairment Loss	0	0
Net Carrying Value, ending balance	$ 2,434	$ 3,159
Patents
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	8 years	8 years
Gross Carrying Amount, beginning balance	$ 6,796	$ 6,796
Accumulated Amortization	(2,542)	(2,334)
Accumulated Impairment Loss	0	0
Net Carrying Value, ending balance	$ 4,254	$ 4,462
Other
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	2 years	2 years
Gross Carrying Amount, beginning balance	$ 618	$ 618
Accumulated Amortization	(568)	(544)
Accumulated Impairment Loss	0	0
Net Carrying Value, ending balance	$ 50	$ 74

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Total Estimated Annual Future Amortization Expense for Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Disclosure Total Estimated Annual Future Amortization Expense For Acquired Intangible Assets [Abstract]
Remainder of 2019	$ 4,544
2019	3,838
2020	3,389
2021	2,116
2022	1,495
Thereafter	940
Net Carrying Value, ending balance	$ 16,322	$ 17,920

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Impairments and other charges		$ 0
Amortization	$ 1,500,000		$ 1,400,000

Credit Facilities - Additional

Credit Facilities - Additional Information (Details) - USD ($)	Feb. 27, 2018	Mar. 31, 2019	Mar. 22, 2013
Line of Credit Facility [Line Items]
Line of credit, available borrowings	$ 200,000,000		$ 50,000,000
Current borrowing capacity	$ 50,000,000		$ 10,000,000
Outstanding borrowings		$ 0
Base Rate
Line of Credit Facility [Line Items]
Basis Spread on Variable Rate	0.50%
London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis Spread on Variable Rate	1.00%
Minimum | Base Rate
Line of Credit Facility [Line Items]
Basis Spread on Variable Rate	0.25%
Minimum | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis Spread on Variable Rate	1.25%
Maximum | Base Rate
Line of Credit Facility [Line Items]
Basis Spread on Variable Rate	0.75%
Maximum | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis Spread on Variable Rate	1.75%

Impairments and Other Charges_2

Impairments and Other Charges (Details) $ in Millions	Mar. 05, 2019USD ($)
Property, Plant and Equipment [Abstract]
Lease impairment	$ 14.2
Leasehold improvement impairment	14.3
Employee severance cost	$ 1.3

Legal Proceedings - Narrative (

Legal Proceedings - Narrative (Details)	Nov. 14, 2017Lawsuitpatent
Lawsuit Against 3Shape AS
Loss Contingencies [Line Items]
Number of lawsuits/complaints	6
Patents Allegedly Infringed upon | patent	26
Violation Of Trade Laws 3Shape
Loss Contingencies [Line Items]
Number of lawsuits/complaints	2
Patent Infringement By 3Shape
Loss Contingencies [Line Items]
Number of lawsuits/complaints	4

Commitments and Contingencies -

Commitments and Contingencies - Other Commitments (Details) $ in Thousands	Jan. 29, 2019USD ($)	Jan. 15, 2019USD ($)floor	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Apr. 30, 2019USD ($)	Jan. 30, 2019USD ($)
Property, Plant and Equipment [Line Items]
Property Plant And Equipment, Number Of Floors Purchased | floor		5
Payments to Acquire Property, Plant, and Equipment		$ 27,000	$ 35,261	$ 57,578
Property Plant And Equipment, Number Of Floors Under Additional Purchase Option | floor		3
Purchase And Sale Agreement Purchase Price	$ 58,100
Purchase And Sale Agreement, Cash Paid						$ 2,000
Subsequent Event
Property, Plant and Equipment [Line Items]
Purchase And Sale Agreement, Cash Paid					$ 56,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)$ / sharesshares
Incentive Plan 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance	27,783,379
Number of shares available for issuance	5,297,058
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercised	7,800
Exercised | $ / shares	$ 7.89
Employee Stock Purchase Plan 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares available	2,400,000
Number of shares remaining	490,417
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unamortized compensation cost | $	$ 125.3
Weighted average period of total unamortized cost (in years)	2 years 7 months 6 days
Market Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unamortized compensation cost | $	$ 58
Weighted average period of total unamortized cost (in years)	1 year 9 months 18 days
Market Performance Based Restricted Stock Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of market-performance based restricted stock units eligible to vest over the vesting period	250.00%
Market Performance Based Restricted Stock Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of granted market-performance based restricted stock units	3 years
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unamortized compensation cost | $	$ 10.3
Weighted average period of total unamortized cost (in years)	1 year

Stockholders' Equity - Stock-Ba

Stockholders' Equity - Stock-Based Compensation Expense Related to All Stock-Based Awards and Employee Stock Purchases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 21,044	$ 15,830
Cost of net revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,112	881
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	16,890	12,578
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 3,042	$ 2,371

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Nonvested Shares (Details) - Restricted Stock Units (RSUs) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)$ / sharesshares
Number of Shares Underlying RSUs
Nonvested as of December 31, 2018 | shares	931
Granted | shares	255
Vested and released | shares	(356)
Forfeited | shares	(20)
Nonvested as of March 31, 2019 | shares	810
Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2018 | $ / shares	$ 129.39
Granted | $ / shares	253.84
Vested and released | $ / shares	95.18
Forfeited | $ / shares	155.77
Nonvested as of March 31, 2019 | $ / shares	$ 183.06
Weighted Average Remaining Contractual Term (in years)
Nonvested as of March 31, 2019	1 year 8 months 1 day
Aggregate Intrinsic Value
Nonvested as of March 31, 2019 | $	$ 230,206

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of MSU Performance (Details) - Market Performance Based Restricted Stock Units $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)$ / sharesshares
Number of Shares Underlying MSUs
Nonvested as of December 31, 2018 | shares	324
Granted | shares	133
Vested and released | shares	(179)
Forfeited | shares	(5)
Nonvested as of March 31, 2019 | shares	273
Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2018 | $ / shares	$ 215.07
Granted | $ / shares	245.69
Vested and released | $ / shares	72.74
Forfeited | $ / shares	265.42
Nonvested as of March 31, 2019 | $ / shares	$ 322.53
Weighted Average Remaining Contractual Term (in years)
Nonvested as of March 31, 2019	1 year 10 months 2 days
Aggregate Intrinsic Value
Nonvested as of March 31, 2019 | $	$ 77,513

Stockholders' Equity - Stock-_2

Stockholders' Equity - Stock-based Compensation Employee Stock Purchase Plan (Details) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected term (in years)	1 year 4 months 24 days	1 year 3 months 18 days
Expected volatility	48.60%	35.70%
Risk-free interest rate	2.50%	1.90%
Expected dividends	0.00%	0.00%
Weighted average fair value at grant date (USD per Share)	$ 90.36	$ 78.38

Common Stock Repurchase Progr_2

Common Stock Repurchase Programs - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 28, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	May 31, 2018	Apr. 30, 2016
Share Repurchases [Line Items]
Repurchased		$ 50,000	$ 100,000
April 2016 Repurchase Program
Share Repurchases [Line Items]
Accelerated share repurchase (shares)				0.7	0.2
Share repurchase price (in dollars per share)				$ 293.21	$ 243.40
Repurchased				$ 200,000	$ 50,000
Repurchase of common stock, common stock authorized							$ 300,000
2017 ASR
Share Repurchases [Line Items]
Accelerated share repurchase (shares)					0.4
Price ($ per share)					$ 146.48
Repurchased					$ 50,000
May 2018 Repurchase Program
Share Repurchases [Line Items]
Accelerated share repurchase (shares)	0.2			0.1
Share repurchase price (in dollars per share)	$ 243.42			$ 356.54
Repurchased	$ 50,000			$ 50,000
Repurchase of common stock, common stock authorized						$ 600,000
Remaining shares under repurchase program		$ 450,000
2018 ASR
Share Repurchases [Line Items]
Accelerated share repurchase (shares)				0.2
Share repurchase price (in dollars per share)				$ 213.18
Repurchased				$ 50,000

Accounting for Income Taxes - A

Accounting for Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Provision for income taxes	$ 8,796	$ 2,902
Effective income tax rate, continuing operations	10.40%	2.90%
Effective Income Tax Rate Reconciliation, Excess Tax Benefit Amount	$ 11,900	$ 23,300
Unrecognized tax benefits	38,000			$ 33,300
Accrued penalties and interest	$ 0
Undistributed earnings of foreign subsidiaries				533,500
Amount of no longer indefinitely reinvested foreign earnings				239,200
Amount of indefinitely reinvested foreign earnings				$ 294,300
National Corporate Tax Rate				30.00%
Scenario, Forecast | Subsequent Event
Income Tax Contingency [Line Items]
National Corporate Tax Rate			30.00%

Computation of Basic and Dilute

Computation of Basic and Diluted Net Income Per Share Attributable to Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 71,848	$ 95,866
Weighted average common shares outstanding, basic	79,860	80,036
Dilutive effect of potential common stock	827	1,592
Total shares, diluted	80,687	81,628
Net income per share, basic	$ 0.90	$ 1.20
Net income per share, diluted	$ 0.89	$ 1.17

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Non-cash investing and financing activities:
Fixed assets acquired with accounts payable or accrued liabilities	$ 13,113	$ 18,739
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	3,820	0
Financing cash flows from finance leases	2,190	0
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	15,984	0
Finance leases	$ 51,064	$ 0

Segments and Geographical Inf_3

Segments and Geographical Information - Additional Information (Details)	3 Months Ended
	Mar. 31, 2019segment
Disclosure Segments And Geographical Information Additional Information [Abstract]
Number of reportable segments	2

Segments and Geographical Inf_4

Segments and Geographical Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Net revenues	$ 548,971	$ 436,924
Gross profit	402,096	327,408
Income from operations	87,701	98,192
Interest income	2,633	2,176
Impairments and other charges	29,782	0
Depreciation and amortization	22,678	11,434
Other income (expense), net	(5,746)	177
Net income before provision for income taxes and equity in losses of investee	84,588	100,545
Operating segments
Segment Reporting Information [Line Items]
Income from operations	186,900	177,536
Clear Aligner
Segment Reporting Information [Line Items]
Net revenues	469,205	385,505
Gross profit	351,358	296,976
Income from operations	158,641	161,454
Impairments and other charges	29,782	0
Depreciation and amortization	11,135	6,384
Scanner
Segment Reporting Information [Line Items]
Net revenues	79,766	51,419
Gross profit	50,738	30,432
Income from operations	28,259	16,082
Impairments and other charges	0	0
Depreciation and amortization	2,097	1,104
Unallocated corporate expenses
Segment Reporting Information [Line Items]
Income from operations	(99,199)	(79,344)
Impairments and other charges	0	0
Depreciation and amortization	$ 9,446	$ 3,946

Segments and Geographical Inf_5

Segments and Geographical Information - Net Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Net revenues	$ 548,971	$ 436,924
United States
Segment Reporting Information [Line Items]
Net revenues	279,005	237,103
The Netherlands
Segment Reporting Information [Line Items]
Net revenues	174,744	139,531
China
Segment Reporting Information [Line Items]
Net revenues	42,616	25,586
Other International
Segment Reporting Information [Line Items]
Net revenues	$ 52,606	$ 34,704

Segments and Geographical Inf_6

Segments and Geographical Information - Long-Lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total long-lived assets	$ 631,651	$ 521,329
The Netherlands
Segment Reporting Information [Line Items]
Total long-lived assets	211,302	206,679
United States
Segment Reporting Information [Line Items]
Total long-lived assets	175,167	139,239
Costa Rica
Segment Reporting Information [Line Items]
Total long-lived assets	82,138	80,218
China
Segment Reporting Information [Line Items]
Total long-lived assets	55,676	36,249
Mexico
Segment Reporting Information [Line Items]
Total long-lived assets	33,734	33,240
Other International
Segment Reporting Information [Line Items]
Total long-lived assets	$ 73,634	$ 25,704