Align Technology (ALGN) 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 27, 2018
Document Information [Line Items]
Trading Symbol	ALGN
Entity Registrant Name	ALIGN TECHNOLOGY INC
Entity Central Index Key	1,097,149
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		80,320,082

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net revenues	$ 490,259	$ 356,482	$ 927,183	$ 666,823
Cost of net revenues	124,677	85,565	234,193	160,281
Gross profit	365,582	270,917	692,990	506,542
Operating expenses:
Selling, general and administrative	212,087	162,964	411,712	314,112
Research and development	30,804	24,384	60,395	47,188
Total operating expenses	242,891	187,348	472,107	361,300
Income from operations	122,691	83,569	220,883	145,242
Interest income	1,917	1,441	4,093	2,636
Other income (expense), net	(7,099)	1,771	(6,922)	2,221
Net income before provision for income taxes and equity in losses of investee	117,509	86,781	218,054	150,099
Provision for income taxes	7,703	15,387	10,605	8,164
Equity in losses of investee, net of tax	3,701	2,215	5,478	3,336
Net income	$ 106,105	$ 69,179	$ 201,971	$ 138,599
Net income per share:
Basic (in usd per share)	$ 1.32	$ 0.86	$ 2.52	$ 1.73
Diluted (in usd per share)	$ 1.30	$ 0.85	$ 2.48	$ 1.70
Shares used in computing net income per share:
Basic (in shares)	80,216	80,188	80,127	80,047
Diluted (in shares)	81,471	81,631	81,575	81,668

CONDENSED CONSOLIDATED STATEME3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 106,105	$ 69,179	$ 201,971	$ 138,599
Net change in foreign currency translation adjustment	759	1,199	(283)	740
Change in unrealized (losses) gains on investments, net of tax	(186)	27	(57)	42
Other comprehensive income (loss)	573	1,226	(340)	782
Comprehensive income	$ 106,678	$ 70,405	$ 201,631	$ 139,381

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 547,993	$ 449,511
Marketable securities, short-term	164,629	272,031
Accounts receivable, net of allowance for doubtful accounts of $2,729 and $5,814, respectively	374,371	324,189
Inventories	47,252	31,688
Prepaid expenses and other current assets	126,754	80,948
Total current assets	1,260,999	1,158,367
Marketable securities, long-term	8,061	39,948
Property, plant and equipment, net	447,933	348,793
Equity method investments	49,128	54,606
Goodwill and intangible assets, net	85,307	89,068
Deferred tax assets	45,859	49,334
Other assets	19,302	43,893
Total assets	1,916,589	1,784,009
Current liabilities:
Accounts payable	48,744	36,776
Accrued liabilities	196,754	195,562
Deferred revenues	321,148	267,713
Total current liabilities	566,646	500,051
Income tax payable	115,701	114,091
Other long-term liabilities	15,283	15,579
Total liabilities	697,630	629,721
Commitments and contingencies (Notes 8 and 9)
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; 80,313 and 80,040 issued and outstanding, respectively)	8	8
Additional paid-in capital	844,599	886,435
Accumulated other comprehensive income (loss), net	911	571
Retained earnings	373,441	267,274
Total stockholders’ equity	1,218,959	1,154,288
Total liabilities and stockholders’ equity	$ 1,916,589	$ 1,784,009

CONDENSED CONSOLIDATED BALANCE5

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accounts receivable, allowance for doubtful accounts	$ 2,729	$ 5,814
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	80,313	80,040
Common stock, shares outstanding	80,313	80,040

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 201,971	$ 138,599
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred taxes	3,667	6,145
Depreciation and amortization	24,066	16,743
Stock-based compensation	32,720	29,057
Equity in losses of investee	5,478	3,336
Other non-cash operating activities	4,543	5,837
Changes in assets and liabilities, net of effects of acquisitions:
Accounts receivable	(44,266)	(52,038)
Inventories	(15,586)	(8,616)
Prepaid expenses and other assets	(9,366)	388
Accounts payable	10,743	4,410
Accrued and other long-term liabilities	(53,442)	(14,802)
Long-term income tax payable	1,610	(551)
Deferred revenues	54,983	29,580
Net cash provided by operating activities	217,121	158,088
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions, net of cash acquired	0	(8,953)
Purchase of property, plant and equipment	(115,295)	(78,045)
Purchase of marketable securities	(78,405)	(212,226)
Proceeds from maturities of marketable securities	207,475	173,094
Proceeds from sales of marketable securities	9,560	32,352
Loan advances to equity investee	0	(15,000)
Loan repayment from equity investee	30,000	0
Other investing activities	668	(2,940)
Net cash provided by (used in) investing activities	54,003	(111,718)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	8,585	7,521
Common stock repurchases	(100,000)	(38,793)
Equity forward contract related to accelerated share repurchase	0	15,000
Employees’ taxes paid upon the vesting of restricted stock units	(79,330)	(37,968)
Net cash used in financing activities	(170,745)	(84,240)
Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash	(1,923)	3,640
Net increase (decrease) in cash, cash equivalents, and restricted cash	98,456	(34,230)
Cash, cash equivalents, and restricted cash at beginning of the period	450,125	393,019
Cash, cash equivalents, and restricted cash at end of the period	548,581	358,789
SUPPLEMENTAL CASH FLOW INFORMATION:
Accounts payable or accrued liabilities related to property, plant and equipment	20,854	20,291
Conversion of convertible notes receivable into equity securities	$ 4,862	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
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 and six months ended June 30, 2018 and 2017 , our comprehensive income for the three and six months ended June 30, 2018 and 2017 , our financial position as of June 30, 2018 and our cash flows for the six months ended June 30, 2018 and 2017 . The Condensed Consolidated Balance Sheet as of December 31, 2017 was derived from the December 31, 2017 audited financial statements and have been recast to reflect the adoption of accounting standards as described below. It does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S.”). During the first quarter of fiscal year 2018, we adopted the Accounting Standards Codification (“ASC”) 606, “ Revenues from Contracts with Customers, ” using the full retrospective method and Accounting Standards Update (“ASU”) 2016-18, “ Statement of Cash Flows - Restricted Cash, ” on a retrospective basis. The Condensed Consolidated Balance Sheet as of December 31, 2017 and the Condensed Consolidated Statement of Cash Flow for the six months ended June 30, 2017 have been recast to comply with the adoption of these standards. The results of operations for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 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, 2017 . 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 Revenue Recognition policy and Investments in Privately Held Companies policy are discussed below: Revenue Recognition Our revenues are derived primarily from the sale of aligners, scanners, and services from our Clear Aligner and Scanner segments. We enter into sales contracts that may consist of multiple distinct performance obligations where certain performance obligations of the sales contract are not delivered in one reporting period. We measure and allocate revenue according to ASC 606-10, “ Revenues from Contracts with Customers. ” We identify a performance obligation as distinct if both of the following criteria are true: the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer and the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract. Determining the standalone selling price (“SSP”) and allocation of consideration from a contract to the individual performance obligations, and the appropriate timing of revenue recognition, is the result of significant qualitative and quantitative judgments. Management considers a variety of factors such as historical sales, usage rates, costs, and expected margin, which may vary over time depending upon the unique facts and circumstances related to each performance obligation in making these estimates. While changes in the allocation of the SSP between performance obligations will not affect the amount of total revenue recognized for a particular contract, any material changes could impact the timing of revenue recognition, which would have a material effect on our financial position and result of operations. This is because the contract consideration is allocated to each performance obligation, delivered or undelivered, at the inception of the contract based on the SSP of each distinct performance obligation. Clear Aligner We enter into contracts (“treatment plan(s)”) that involve multiple future performance obligations. Invisalign Full, Invisalign Teen, and Invisalign Assist products include optional additional aligners at no charge for a period of up to five years after initial shipment and Invisalign Go includes optional additional aligners at no charge for a period of up to two years after initial shipment. Invisalign Teen also includes up to six optional replacement aligners in the price of the product and may be ordered by the dental professional any time throughout treatment. Invisalign Lite includes one optional case refinement in the price of the product. Case refinement is a finishing tool used to adjust a patient’s teeth to the desired final position and may be elected by the dental professional at any time during treatment; however, it is generally ordered in the last stages of orthodontic treatment. We determined that our treatment plans comprise the following performance obligations that also represent distinct deliverables: initial aligners, additional aligners, case refinement, and replacement aligners. We elected to take the practical expedient to consider shipping and handling costs as activities to fulfill the performance obligation. We allocate revenue for each treatment plan based on each unit’s SSP and recognize the revenue over the manufacturing period, typically 1 to 3 days, as the aligners do not have an alternative use and we have enforceable rights to payment. As we collect most consideration upfront, we considered whether a significant financing component exists; however, as the delivery of the performance obligations are at the customer’s discretion, we concluded that no significant financing component exists. Scanner We sell intraoral scanners and computer-aided design/computer-aided manufacturing (“CAD/CAM”) services through both our direct sales force and distribution partners. The intraoral scanner sales price includes one year of warranty and unlimited scanning services. The customer may, for additional fees, also select extended warranty and unlimited scanning services for periods beyond the initial year. When intraoral scanners are sold with an unlimited scanning service agreement and/or extended warranty, we allocate revenue based on each element’s SSP. We estimate the SSP of each element, taking into consideration historical prices as well as our discounting strategies. Revenue is then recognized over time as the monthly services are rendered and upon shipment for the scanner, as that is when we deem the customer to have obtained control. Most consideration is collected upfront and in cases where there are payment plans, consideration is collected by the 1 year mark and therefore, there are no significant financing components. Warranties For both Clear Aligner and Scanner segments, we offer an assurance warranty which provides the customer assurance that the product will function as the parties intended because it complies with agreed-upon specifications, and thus is not treated as a separate performance obligation and will continue to be accrued in accordance with the Financial Accounting Standards Board (“FASB”) guidance on guarantees. Volume Discounts In certain situations, we offer promotions in which the discount will increase depending upon the volume purchased over time. We concluded that in these situations, the promotions can represent either variable consideration or options, depending upon the specifics of the promotion. In the event the promotion contains an option, the option is considered a material right and, therefore, included in the accounting for the initial arrangement. We estimate the average anticipated discount over the lifetime of the promotion or contract, and apply that discount to each unit as it is sold. On a quarterly basis, we review our estimates and, if needed, updates are made and changes are applied prospectively. Costs to Obtain a Contract We offer a variety of commission plans to our salesforce; each plan has multiple components. To match the costs to obtain a contract to the associated revenue, we evaluate the individual components and capitalize the eligible components, recognizing the costs over the treatment period. Unfulfilled Performance Obligations for Clear Aligners and Scanners Our unfilled performance obligations as of June 30, 2018 and the estimated revenue expected to be recognized in the future related to these performance obligations are $358.0 million . This includes performance obligations from the Clear Aligner segment, primarily the shipment of additional aligners, which are fulfilled over 1 to 5 years, and performance obligations from the iTero scanner segment, primarily contracted deliveries of additional scanners and support, which are fulfilled over 1 to 5 years. The estimate includes both product and service unfulfilled performance obligations and the time range reflects our best estimate of when we will transfer control to the customer and may change based on customer usage patterns, timing of shipments, readiness of customers’ facilities for installation, and manufacturing availability. Contract Balances The timing of revenue recognition results in deferred revenues being recognized on the Condensed Consolidated Balance Sheet. For both aligners and scanners, we usually collect the total consideration owed prior to all performance obligations being performed and payment terms vary from net 30 to net 90 days. Contract liabilities are recorded as deferred revenue balances, which are generated based upon timing of invoices and recognition patterns, not payments. If the revenue recognition exceeds the billing, the exceeded amount is considered unbilled receivable and a contract asset. Conversely, if the billing occurs prior to the revenue recognition, the amount is considered deferred revenue and a contract liability. Investments in Privately Held Companies Investments in privately held companies in which we can exercise significant influence but do not own a majority equity interest or otherwise control are accounted for under ASC 323, “ Investments—Equity Method and Joint Ventures. ” Equity securities qualified as equity method investments are reported on our Condensed Consolidated Balance Sheet as a single amount, and we record our share of their operating results within equity in losses of investee, net of tax, in our Condensed Consolidated Statement of Operations. Investments in privately held companies in which we can not exercise significant influence and do not own a majority equity interest or otherwise control are accounted for under ASC 321, “ Investments—Equity Securities. ” The equity securities without readily determinable fair values are recorded at cost and adjusted for impairments and observable price changes with a same or similar security from the same issuer (“Measurement Alternative”). Equity securities under ASC 321 are reported on our Condensed Consolidated Balance Sheet as other assets, and we record a change in carrying value of our equity securities, if any, in other income (expense), net in our Condensed Consolidated Statement of Operations. Equity securities are evaluated for impairment as events or circumstances indicate that there is an other-than-temporary loss in value. The decrease in value is recognized in the period the impairment occurs and recorded in other income (expense), net in the Condensed Consolidated Statement of Operations. Recent Accounting Pronouncements (i) New Accounting Updates Recently Adopted In May 2014, the FASB released ASU 2014-09, “ Revenue from Contracts with Customers, ” (Topic 606) to supersede nearly all existing revenue recognition guidance under GAAP. The core principle of the standard is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for the goods or services. We adopted the guidance in the first quarter of fiscal year 2018 by applying the full retrospective method. The impact of adoption was primarily related to the Clear Aligner segment. Our disaggregation of revenue can be found in Note 14 “Segments and Geographical Information.” We elected to take the practical expedient to exclude from the transaction price all taxes assessed by a governmental authority. In preparation for adoption of the standard, we have reviewed and, where necessary, implemented additional key system functionalities and internal controls to enable the preparation of financial information. Prior periods have been retrospectively adjusted, and we recognized cumulative effect of adopting the guidance as an adjustment to our opening balance of retained earnings as of January 1, 2016. The adoption of ASU 2014-09 did not have a material impact on our Condensed Consolidated Statements of Operations, Condensed Consolidated Statements of Comprehensive Income or Condensed Consolidated Statements of Cash Flows for the historical periods presented in the Item 1 Financial Statements section. Consolidated Balance Sheet line items, which reflect the adoption of the ASU 2014-09 are as follows (in thousands): December 31, 2017 As Previously Reported Adjustment As Adjusted Asset Accounts: Accounts receivable, net $ 322,825 $ 1,364 $ 324,189 Deferred tax assets 50,059 (725 ) 49,334 Other assets 38,379 5,514 43,893 Liability and Stockholders’ Equity Accounts: Accrued liabilities $ 194,198 $ 1,364 $ 195,562 Deferred revenues 266,842 871 267,713 Retained earnings 263,356 3,918 267,274 In August 2016, the FASB issued ASU 2016-15, “Classification of Certain Cash Receipts and Cash Payments,” which clarifies the presentation and classification of certain cash receipts and cash payments in the statements of cash flows. The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2017. We adopted the standard in the first quarter of fiscal year 2018 on a retrospective basis, and it did not have an impact on our Condensed Consolidated Statements of Cash Flows. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows—Restricted Cash,” which provides guidance to address the classification and presentation of changes in restricted cash in the statements of cash flows . The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2017 on a retrospective basis. We adopted the guidance in the first quarter of fiscal year 2018 on a retrospective basis and presented the changes in the total of cash, cash equivalents, and restricted cash in the Condensed Consolidated Statements of Cash Flows. Condensed Consolidated Statement of Cash Flows line items, which reflect the adoption of the ASU 2016-18, are as follows (in thousands): Six Months Ended As Previously Reported Adjustment As Adjusted Cash Flows from Investing Activities Other investing activities $ 224 $ (3,164 ) $ (2,940 ) Net cash used in investing activities (108,554 ) (3,164 ) (111,718 ) Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash 3,613 27 3,640 Net decrease in cash, cash equivalents, and restricted cash (31,093 ) (3,137 ) (34,230 ) Cash, cash equivalents, and restricted cash at beginning of the period 389,275 3,744 393,019 Cash, cash equivalents, and restricted cash at end of the period $ 358,182 $ 607 $ 358,789 In May 2017, the FASB issued ASU 2017-09, “ Compensation — Stock Compensation (Topic 718): Scope of Modification Accounting,” to clarify when to account for a change to the terms or conditions of a share-based payment award as a modification. The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2017 on a prospective basis. We adopted the standard in the first quarter of fiscal year 2018 on a prospective basis which did not have an impact on our condensed consolidated financial statements and related disclosures. (ii) Recent Accounting Updates Not Yet Effective In February 2016, the 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. We plan to adopt the standard in the first quarter of fiscal year 2019 by electing the package of practical expedients available in the standard. We are in the process of evaluating changes to our systems, processes and controls in order to adopt the new standard in the first quarter of fiscal year 2019. While we are currently evaluating the impact of the adoption of this guidance on our consolidated financial statements, we expect the adoption will have a material increase in assets and liabilities on our consolidated balance sheet. 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. 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 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 are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures.

Investments and Fair Value Meas

Investments and Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Investments and Fair Value Measurements	Investments and Fair Value Measurements Marketable Securities As of June 30, 2018 and December 31, 2017 , 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 June 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 32,656 $ — $ — $ 32,656 Corporate bonds 84,246 1 (205 ) 84,042 U.S. government agency bonds 14,013 — (41 ) 13,972 U.S. government treasury bonds 32,953 3 (19 ) 32,937 Certificates of deposit 1,022 — — 1,022 Total marketable securities, short-term $ 164,890 $ 4 $ (265 ) $ 164,629 Long-term June 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government agency bonds $ 7,006 $ — $ (74 ) $ 6,932 Corporate bonds 1,128 1 — 1,129 Total marketable securities, long-term $ 8,134 $ 1 $ (74 ) $ 8,061 Short-term December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 58,503 $ — $ (1 ) $ 58,502 Corporate bonds 145,728 3 (174 ) 145,557 U.S. government agency bonds 3,013 — (7 ) 3,006 U.S. government treasury bonds 60,650 — (70 ) 60,580 Certificates of deposit 4,386 — — 4,386 Total marketable securities, short-term $ 272,280 $ 3 $ (252 ) $ 272,031 Long-term December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government agency bonds $ 15,023 $ — $ (68 ) $ 14,955 Corporate bonds 25,067 2 (76 ) 24,993 Total marketable securities, long-term $ 40,090 $ 2 $ (144 ) $ 39,948 Cash equivalents are not included in the table 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 June 30, 2018 and December 31, 2017 . Amounts reclassified to earnings from accumulated other comprehensive income (loss), net related to unrealized gains or losses were not material for the three and six months ended June 30, 2018 and 2017. For the three and six months ended June 30, 2018 and 2017, realized gains or losses were not material. Our fixed-income securities investment portfolio consists of investments that have a maximum effective maturity of 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 six months as of June 30, 2018 and December 31, 2017 , 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 June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 One year or less $ 164,629 $ 272,031 Due in greater than one year 8,061 39,948 Total available for sale short-term and long-term marketable securities $ 172,690 $ 311,979 Investments in Privately Held Companies Our investments in privately held companies as of June 30, 2018 and December 31, 2017 are as follows (in thousands): June 30, 2018 December 31, 2017 Equity securities under the equity method investment 1 $ 49,128 $ 54,606 Equity securities without readily determinable fair values 2 $ 4,862 $ — 1 Refer to Note 4 “Equity Method Investments” of the Notes to Condensed Consolidated Financial Statements for more information. 2 In April 2018, the convertible notes receivable (recurring level 3 investment) was converted into equity securities as a result of qualified financing secured by the private company in accordance with ASC 321, “Investments—Equity Securities.” The equity securities issued upon conversion are reported as a nonrecurring investment within “Other Assets” in our Condensed Consolidated Balance Sheet. From the date of conversion through June 30, 2018, there were no fair value adjustments. 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 June 30, 2018 and December 31, 2017 (in thousands): Description Balance as of June 30, 2018 Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 390,103 $ 390,103 $ — $ — Short-term investments: Commercial paper 32,656 — 32,656 — Corporate bonds 84,042 — 84,042 — U.S. government agency bonds 13,972 — 13,972 — U.S. government treasury bonds 32,937 32,937 — — Certificates of deposit 1,022 — 1,022 — Long-term investments: U.S. government agency bonds 6,932 — 6,932 — Corporate bonds 1,129 — 1,129 — Prepaid expenses and other current assets: Israeli funds 3,099 — 3,099 — $ 565,892 $ 423,040 $ 142,852 $ — Description Balance as of December 31, 2017 Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 253,155 $ 253,155 $ — $ — Commercial paper 7,246 — 7,246 — Corporate bonds 2,016 — 2,016 — Short-term investments: Commercial paper 58,502 — 58,502 — Corporate bonds 145,557 — 145,557 — U.S. government agency bonds 3,006 — 3,006 — U.S. government treasury bonds 60,580 60,580 — — Certificates of deposit 4,386 — 4,386 — Long-term investments: U.S. government agency bonds 14,955 — 14,955 — Corporate bonds 24,993 — 24,993 — Prepaid expenses and other current assets: Israeli funds 3,075 — 3,075 — Short-term notes receivable 4,476 — — 4,476 $ 581,947 $ 313,735 $ 263,736 $ 4,476 Derivative Financial Instruments In March 2018, we began entering 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 both the three and six months ended June 30, 2018 was $5.4 million . As of June 30, 2018 , 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 June 30, 2018 (in thousands): June 30, 2018 Local Currency Amount Notional Contract Amount (USD) Euro €64,400 $ 75,322 Chinese Yuan ¥150,000 22,574 Canadian Dollar C$28,000 21,277 British Pound £13,000 17,159 Japanese Yen ¥1,513,000 13,670 Brazilian Real R$37,300 9,582 Australian Dollar A$7,300 5,390 $ 164,974

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Inventories Inventories consist of the following (in thousands): June 30, December 31, Raw materials $ 22,976 $ 12,721 Work in process 12,396 12,157 Finished goods 11,880 6,810 Total inventories $ 47,252 $ 31,688 Other Assets Other assets consist of the following (in thousands): June 30, December 31, Capitalized commissions $ 7,947 $ 5,515 Equity securities 4,862 — Security deposits 3,734 3,557 Loan receivable from equity investee — 30,000 Other long-term assets 2,759 4,821 Total other assets $ 19,302 $ 43,893 Accrued Liabilities Accrued liabilities consist of the following (in thousands): June 30, December 31, Accrued payroll and benefits $ 87,697 $ 103,004 Accrued expenses 36,776 27,318 Accrued fixed assets 12,889 11,362 Accrued customer credits 11,552 5,373 Accrued income taxes 7,764 12,405 Accrued warranty 7,286 5,929 Accrued professional fees 6,876 6,316 Accrued sales tax and value added tax 5,955 5,503 Accrued sales return reserve 1 5,554 1,364 Accrued sales rebate 3,772 11,209 Other accrued liabilities 10,633 5,779 Total accrued liabilities $ 196,754 $ 195,562 1 December 31, 2017 balance has been reclassified from accounts receivable, net to reflect the adoption of ASU 2014-09 ( Refer to Note 1 “Summary of Significant Accounting Policies” of the Notes to Condensed Consolidated Financial Statements for more information). 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 June 30, 2018 and 2017 consists of the following activity (in thousands): Six Months Ended 2018 2017 Balance at beginning of period $ 5,929 $ 3,841 Charged to cost of revenues 5,728 3,690 Actual warranty expenditures (4,371 ) (2,503 ) Balance at end of period $ 7,286 $ 5,028 Deferred Revenues Deferred revenues consist of the following (in thousands): June 30, December 31, Deferred revenues - current $ 321,148 $ 267,713 Deferred revenues - long-term 1 7,625 4,588 1 Included in other long-term liabilities on our Condensed Consolidated Balance Sheet. During the three months ended June 30, 2018 and June 30, 2017 , we recognized revenue of $490.3 million and $356.5 million , respectively, of which $102.0 million and $61.3 million were included in the deferred revenue balance at December 31, 2017 and December 31, 2016 , respectively. During the six months ended June 30, 2018 and June 30, 2017 , we recognized revenue of $927.2 million and $666.8 million , respectively, of which $187.7 million and $112.8 million were included in the deferred revenues balance at December 31, 2017 and December 31, 2016 , respectively.

Equity Method Investments

Equity Method Investments	6 Months Ended
	Jun. 30, 2018
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 . The investment is accounted for under an equity method investment and the investee, SDC, is considered a related party. The investment is reported in our Condensed Consolidated Balance Sheet under equity method investments, and 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. On July 24, 2017, we purchased an additional 2% equity interest in SDC for $12.8 million . As a result of this purchase, we hold a 19% equity interest in SDC on a fully diluted basis. As of June 30, 2018 and December 31, 2017 , the balance of our equity method investments was $49.1 million and $54.6 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. We commenced supplying aligners to SDC in October 2016. 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 June 30, 2018 and December 31, 2017 , the balance of accounts receivable due from SDC was $11.8 million and $14.3 million , respectively. For the three months ended June 30, 2018 and 2017 , net revenues recognized from SDC were $8.6 million and $3.0 million , respectively, and for the six months ended June 30, 2018 and 2017 , net revenues recognized from SDC were $13.9 million and $3.6 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 ( Refer to Note 8 “Legal Proceedings” of the Notes to Condensed Consolidated Financial Statements for SDC legal proceedings discussion).

Business Combinations

Business Combinations	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Business Combinations	Business Combinations During the first quarter of 2017, we completed the acquisitions of certain of our distributors for the total cash consideration of approximately $9.5 million including cash acquired. We recorded $1.9 million of net tangible liabilities, $8.2 million of identifiable intangible assets and $3.2 million of goodwill. The goodwill is primarily related to the benefit we expect to obtain from direct sales as we believe that the transition from our distributor arrangements to a direct sales model will increase our net revenues in the region as we will experience higher average sales prices (“ASP”) compared to our discounted ASP under the distribution agreements. The goodwill is not deductible for tax purposes. Pro forma results of operations for these acquisitions have not been presented as they were not material to our results of operations, either individually or in aggregate, for the three and six months ended June 30, 2017.

Goodwill and Long-lived Assets

Goodwill and Long-lived Assets	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill The change in the carrying value of goodwill for the six months ended June 30, 2018 , all attributable to our Clear Aligner reporting unit, is as follows (in thousands): Total Balance as of December 31, 2017 $ 64,614 Adjustments 1 (434 ) Balance as of June 30, 2018 $ 64,180 1 The adjustments to goodwill during the period were a result of foreign currency translation. During the fourth quarter of fiscal 2017, 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 Accumulated Amortization Accumulated Impairment Loss Net Carrying Trademarks 15 $ 7,100 $ (1,838 ) $ (4,179 ) $ 1,083 Existing technology 13 12,600 (4,986 ) (4,328 ) 3,286 Customer relationships 11 33,500 (15,612 ) (10,751 ) 7,137 Reacquired rights 3 7,500 (2,894 ) — 4,606 Patents 8 6,796 (1,919 ) — 4,877 Other 2 618 (480 ) — 138 Total intangible assets $ 68,114 $ (27,729 ) $ (19,258 ) $ 21,127 Weighted Average Amortization Period (in years) Gross Carrying Amount as of December 31, 2017 Accumulated Amortization Accumulated Impairment Loss Net Carrying Value as of December 31, 2017 Trademarks 15 $ 7,100 $ (1,769 ) $ (4,179 ) $ 1,152 Existing technology 13 12,600 (4,704 ) (4,328 ) 3,568 Customer relationships 11 33,500 (14,681 ) (10,751 ) 8,068 Reacquired rights 3 7,500 (1,356 ) — 6,144 Patents 8 6,798 (1,504 ) — 5,294 Other 2 618 (390 ) — 228 Total intangible assets $ 68,116 $ (24,404 ) $ (19,258 ) $ 24,454 The total estimated annual future amortization expense for these acquired intangible assets as of June 30, 2018 is as follows (in thousands): Fiscal Year Ending December 31, Amortization Remainder of 2018 $ 3,149 2019 6,184 2020 3,855 2021 3,389 2022 2,116 Thereafter 2,434 Total $ 21,127 Amortization for the three months ended June 30, 2018 and 2017 was $1.5 million and $1.8 million , respectively, and amortization for the six months ended June 30, 2018 and 2017 was $3.0 million and $3.2 million , respectively.

Credit Facilities

Credit Facilities	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 , we had no outstanding borrowings under this credit facility and were in compliance with the conditions and performance requirements.

Legal Proceedings (Notes)

Legal Proceedings (Notes)	6 Months Ended
	Jun. 30, 2018
Legal Proceedings [Abstract]
Legal Proceedings	Legal Proceedings Patent Infringement Lawsuit On November 14, 2017, Align filed six patent infringement lawsuits asserting 26 patents against 3Shape A/S, 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 United States District Court for the District of Delaware alleging patent infringement by 3Shape’s Trios intraoral scanning system and Dental System software. All of these district court complaints seek monetary damages and injunctive relief against further infringement. SDC Dispute On April 5, 2018, SDC Financial LLC, SmileDirectClub LLC, and the Members of SDC Financial LLC other than Align (collectively, the "SDC Entities") initiated proceedings that seek, among other forms of relief, to preliminarily and permanently enjoin all activities related to the Invisalign store pilot project, require Align to close the 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 the current capital account balance. On June 29, 2018, the Chancery Court for Davidson County, Tennessee, denied the SDC Entities’ request for a temporary injunction to prevent Align from opening additional Invisalign stores. Align continues to dispute the allegations that it has breached its obligations to the SDC Entities under applicable law and will oppose and vigorously defend itself at the arbitration proceedings currently scheduled for December 2018. This dispute does not impact Align’s existing supply agreement with SDC which remains in place through 2019 and includes a minimum volume commitment. 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. 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.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases As of June 30, 2018 , minimum future lease payments for non-cancelable operating leases are as follows (in thousands): Fiscal Year Ending December 31, Operating Leases Remainder of 2018 $ 9,213 2019 17,350 2020 13,503 2021 11,827 2022 9,617 Thereafter 20,738 Total minimum future lease payments $ 82,248 Sublease income is not material and excluded from the table above. Other Commitments On July 25, 2016, we entered into a Loan and Security Agreement (the “Loan Agreement”) with SDC and subsequently amended on July 24, 2017 to provide a loan of up to $30.0 million in one or more advances to SDC (the “Loan Facility”). On February 7, 2018, $30.0 million of outstanding advances and related accrued interest were repaid in full, and the Loan Agreement was terminated ( Refer to Note 4 “Equity Method Investments” of the Notes to Condensed Consolidated Financial Statements for more information on our investments in SDC). On November 27, 2017, we entered into a Purchase Agreement with one of our existing single source suppliers. Under the terms of the original agreement, we are required to purchase a minimum approximately $305.2 million of aligner materials over the next 4 years . On May 29, 2018, we entered into an amendment to the Purchase Agreement with the existing single source supplier to increase the original term of the agreement to 5 years and total minimum purchase amount to approximately $425.9 million . Off-Balance Sheet Arrangements As of June 30, 2018 , 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 June 30, 2018 , we did not have any material indemnification claims that were probable or reasonably possible.

Stockholders' Equity (Notes)

Stockholders' Equity (Notes)	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Stockholders' Equity	Stockholders’ Equity Summary of Stock-Based Compensation Expense As of June 30, 2018 , the 2005 Incentive Plan (as amended) has a total reserve of 27,783,379 shares of which 6,066,597 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 and six months ended June 30, 2018 and 2017 is as follows (in thousands): Three Months Ended Six Months Ended 2018 2017 2018 2017 Cost of net revenues $ 900 $ 768 $ 1,781 $ 1,693 Selling, general and administrative 13,216 11,218 25,794 22,934 Research and development 2,774 2,259 5,145 4,430 Total stock-based compensation $ 16,890 $ 14,245 $ 32,720 $ 29,057 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. Activity for the six months ended June 30, 2018 under the stock option plans is set forth below: Number of Shares Underlying Stock Options (in thousands) Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding as of December 31, 2017 75 $ 11.36 Exercised (61 ) 12.13 Cancelled or expired — — Outstanding as of June 30, 2018 14 $ 7.96 0.62 $ 4,651 Vested at June 30, 2018 14 $ 7.96 0.62 $ 4,651 Exercisable at June 30, 2018 14 $ 7.96 0.62 $ 4,651 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 six months ended June 30, 2018 is as follows: Shares Underlying RSUs (in thousands) Weighted Average Grant Date Fair Value Weighted Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Nonvested as of December 31, 2017 1,341 $ 82.30 Granted 214 256.85 Vested and released (491 ) 71.93 Forfeited (65 ) 98.99 Nonvested as of June 30, 2018 999 $ 123.73 1.44 $ 341,829 As of June 30, 2018 , we expect to recognize $98.3 million of total unamortized compensation cost, net of estimated forfeitures, related to RSUs over a weighted average period of 2.3 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 two to three years. For MSUs granted during the six months ended June 30, 2018 , the maximum number of MSUs which will be eligible to vest are between 250% to 300% of the MSUs initially granted. The following table summarizes the MSU performance for the six months ended June 30, 2018 : 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, 2017 428 $ 78.53 Granted 208 261.86 Vested and released (312 ) 62.41 Forfeited — — Nonvested as of June 30, 2018 324 $ 211.91 1.66 $ 110,922 As of June 30, 2018 , we expect to recognize $48.6 million of total unamortized compensation cost, net of estimated forfeitures, related to MSUs over a weighted average period of 1.7 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 June 30, 2018 , we have 647,363 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: Six Months Ended 2018 2017 Expected term (in years) 1.3 1.2 Expected volatility 35.7 % 26.1 % Risk-free interest rate 1.9 % 0.9 % Expected dividends — — Weighted average fair value at grant date $ 78.38 $ 26.09 As of June 30, 2018 , there was $1.6 million of total unamortized compensation costs related to employee stock purchases which we expect to be recognized over a weighted average period of 0.4 year.

Common Stock Repurchase Program

Common Stock Repurchase Programs	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Common Stock Repurchase Programs	Common Stock Repurchase Programs April 2014 Repurchase Program In January 2017, we repurchased on the open market approximately 0.04 million shares of our common stock at an average price of $96.37 per share, including commission for an aggregate purchase price of approximately $3.8 million , completing the April 2014 Repurchase Program. April 2016 Repurchase Program On April 28, 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 May 2017, we entered into an accelerated share repurchase agreement ("2017 ASR") to repurchase $50.0 million of our common stock. The 2017 ASR was completed in August 2017. We received a total of approximately 0.4 million shares for an average share price of $146.48 . In November 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 February 2018, we repurchased on the open market approximately 0.4 million shares of our common stock at an average price of $252.24 per share, including commission for an aggregate purchase price of approximately $100.0 million . In July 2018, we repurchased on the open market approximately 0.3 million shares of our common stock at an average price of $350.08 per share, including commissions for an aggregate purchase price of approximately $100.0 million , completing the April 2016 Repurchase Program. May 2018 Repurchase Program On May 23, 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”). As of June 30, 2018 , we have not made any stock repurchases under the May 2018 Repurchase Program.

Accounting for Income Taxes

Accounting for Income Taxes	6 Months Ended
	Jun. 30, 2018
Accounting for Income Taxes	Accounting for Income Taxes Our provision for income taxes was $ 7.7 million and $ 15.4 million for the three months ended June 30, 2018 and 2017 , respectively, representing effective tax rates of 6.6% and 17.7% , respectively. Our provision for income taxes was $10.6 million and $8.2 million for the six months ended June 30, 2018 and 2017 , respectively, representing effective tax rates of 4.9% and 5.4% , respectively. As a result of the enactment of the TCJA, the U.S. federal statutory tax rate decreased from 35% to 21% effective January 1, 2018. Our effective tax rate differs from the statutory federal income tax rate of 21% and 35% for both the three and six months ended June 30, 2018 and 2017 , respectively, mainly as a result of 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 decrease in effective tax rate for the three and six months ended June 30, 2018 compared to the same periods in 2017 is primarily attributable to the decrease in the corporate tax rate from 35% to 21% pursuant to the enactment of the TCJA, offset in part by reduced benefits from foreign earnings being taxed at a lower tax rate, and the increase in excess tax benefits related to stock-based compensation. For the three and six months ended June 30, 2018 , we recognized excess tax benefits of $16.6 million and $39.9 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 2000 . We are currently under examination by the Internal Revenue Service for tax year 2015. 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 $53.2 million and $47.7 million as of June 30, 2018 and December 31, 2017 , respectively, all of which would impact our effective tax rate if recognized. Our total interest and penalties accrued as of June 30, 2018 was $3.6 million . 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. It is reasonably possible that the gross unrecognized tax benefits related to the years that are subject to examination could decrease, whether by payment, release, or a combination of both, in the next 12 months by $28.0 million , which would impact our effective tax rate. 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% for 2018 and 2017 . For the three and six months ended June 30, 2018 , the reduction in income taxes due to the reduced tax rate was minimal. As of December 31, 2017 , undistributed earnings of the Company totaled $606.5 million . We reassessed our capital needs and investment strategy with regard to the indefinite reinvestment of the undistributed earnings from certain of our foreign subsidiaries as a result of the one-time transition tax on cumulative foreign earnings under the TCJA. During the fourth quarter of 2017 , we determined that approximately $591.9 million of the total undistributed foreign earnings are no longer considered to be indefinitely reinvested outside the U.S. As a result, in the fourth quarter of 2017, we recorded a deferred tax liability of approximately $3.3 million , which represents the provisional amount of U.S. state income taxes that would be due in the event these foreign earnings are distributed. The remaining amount of undistributed foreign earnings of approximately $14.7 million continues to be indefinitely reinvested in our international operations. Since U.S. federal income tax has already been provided under the provisions of the TCJA, the additional tax impact of the distribution of such foreign earnings to the U.S. parent would be limited to U.S. state income and withholding taxes and is not significant. As of December 31, 2017 , we recorded a provisional tax charge for the estimated impact of the TCJA of $84.3 million , of which $73.9 million was related to a provisional transition tax liability on the mandatory deemed repatriation of foreign earnings and $10.4 million was related to the remeasurement of certain deferred tax assets and liabilities. During the six months ended June 30, 2018 , the additional provisional tax charge recorded was $0.5 million , primarily resulting from further analysis of our cumulative foreign earnings balances affecting the transition tax liability and the corresponding state tax impact. As we complete our analysis of the TJCA, we may make further adjustments to the provisional amounts, which may impact our provision for income taxes in the period in which the adjustments are made. The TCJA subjects a U.S. shareholder to tax on global intangible low-taxed income (“GILTI”) earned by certain foreign subsidiaries. The FASB Staff Q&A, Topic 740, No. 5, Accounting for Global Intangible Low-Taxed Income, states that an entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. Given the complexity of the GILTI provisions, we are still evaluating the effects of the GILTI provisions and have not yet determined our accounting policy. As of June 30, 2018 , we are still evaluating the GILTI provisions and our analysis of future taxable income that is subject to GILTI. We have included GILTI related to current-year operations only in our estimated annual effective tax rate and have not provided additional GILTI on deferred items.

Net Income Per Share

Net Income Per Share	6 Months Ended
	Jun. 30, 2018
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 Six Months Ended 2018 2017 2018 2017 Numerator: Net income $ 106,105 $ 69,179 $ 201,971 $ 138,599 Denominator: Weighted-average common shares outstanding, basic 80,216 80,188 80,127 80,047 Dilutive effect of potential common stock 1,255 1,443 1,448 1,621 Total shares, diluted 81,471 81,631 81,575 81,668 Net income per share, basic $ 1.32 $ 0.86 $ 2.52 $ 1.73 Net income per share, diluted $ 1.30 $ 0.85 $ 2.48 $ 1.70 For the three and six months ended June 30, 2018 and 2017 , potentially anti-dilutive shares excluded from diluted net income per share related to RSUs, MSUs, stock options and ESPP were not material.

Segments and Geographical Infor

Segments and Geographical Information	6 Months Ended
	Jun. 30, 2018
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 our Invisalign Full, Teen and Assist products. • Non-Comprehensive Products include our Invisalign Express, Invisalign Lite, Invisalign i7 and Invisalign Go products in addition to revenues from the sale of aligners to SDC under our supply agreement. • Non-Case includes our Vivera retainers along with our training and ancillary products for treating malocclusion. • Our Scanner segment consists of intraoral scanning systems and additional services 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 Six Months Ended Net revenues 2018 2017 2018 2017 Clear Aligner $ 433,241 $ 321,036 $ 818,746 $ 603,435 Scanner 57,018 35,446 108,437 63,388 Total net revenues $ 490,259 $ 356,482 $ 927,183 $ 666,823 Gross profit Clear Aligner $ 331,612 $ 250,814 $ 628,588 $ 470,761 Scanner 33,970 20,103 64,402 35,781 Total gross profit $ 365,582 $ 270,917 $ 692,990 $ 506,542 Income from operations Clear Aligner $ 190,287 $ 133,916 $ 351,741 $ 248,650 Scanner 17,670 8,795 33,752 14,799 Unallocated corporate expenses (85,266 ) (59,142 ) (164,610 ) (118,207 ) Total income from operations $ 122,691 $ 83,569 $ 220,883 $ 145,242 Depreciation and amortization Clear Aligner $ 6,759 $ 5,600 $ 13,143 $ 9,963 Scanner 1,169 1,082 2,273 2,119 Unallocated corporate depreciation and amortization 4,704 2,194 8,650 4,661 Total depreciation and amortization $ 12,632 $ 8,876 $ 24,066 $ 16,743 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 Six Months Ended 2018 2017 2018 2017 Total segment income from operations $ 207,957 $ 142,711 $ 385,493 $ 263,449 Unallocated corporate expenses (85,266 ) (59,142 ) (164,610 ) (118,207 ) Total income from operations 122,691 83,569 220,883 145,242 Interest income 1,917 1,441 4,093 2,636 Other income (expense), net (7,099 ) 1,771 (6,922 ) 2,221 Net income before provision for income taxes and equity in losses of investee $ 117,509 $ 86,781 $ 218,054 $ 150,099 Geographical Information Net revenues are presented below by geographic area (in thousands): Three Months Ended Six Months Ended 2018 2017 2018 2017 Net revenues 1 : United States $ 254,020 $ 207,021 $ 491,123 $ 390,294 The Netherlands 156,428 109,532 295,959 209,331 Other International 79,811 39,929 140,101 67,198 Total net revenues $ 490,259 $ 356,482 $ 927,183 $ 666,823 1 Net revenues are attributed to countries based on location of where revenue is recognized. Tangible long-lived assets are presented below by geographic area (in thousands): June 30, December 31, 2017 Long-lived assets 2 : The Netherlands $ 190,130 $ 143,673 United States 129,837 128,171 Costa Rica 61,609 30,738 Mexico 31,289 25,090 China 16,393 5,480 Other International 18,675 15,641 Total long-lived assets $ 447,933 $ 348,793 2 Long-lived assets are attributed to countries based on entity that owns the assets.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
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 and six months ended June 30, 2018 and 2017 , our comprehensive income for the three and six months ended June 30, 2018 and 2017 , our financial position as of June 30, 2018 and our cash flows for the six months ended June 30, 2018 and 2017 . The Condensed Consolidated Balance Sheet as of December 31, 2017 was derived from the December 31, 2017 audited financial statements and have been recast to reflect the adoption of accounting standards as described below. It does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S.”). During the first quarter of fiscal year 2018, we adopted the Accounting Standards Codification (“ASC”) 606, “ Revenues from Contracts with Customers, ” using the full retrospective method and Accounting Standards Update (“ASU”) 2016-18, “ Statement of Cash Flows - Restricted Cash, ” on a retrospective basis. The Condensed Consolidated Balance Sheet as of December 31, 2017 and the Condensed Consolidated Statement of Cash Flow for the six months ended June 30, 2017 have been recast to comply with the adoption of these standards. The results of operations for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 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, 2017 .
Use of estimates	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.
Revenue Recognition	Revenue Recognition Our revenues are derived primarily from the sale of aligners, scanners, and services from our Clear Aligner and Scanner segments. We enter into sales contracts that may consist of multiple distinct performance obligations where certain performance obligations of the sales contract are not delivered in one reporting period. We measure and allocate revenue according to ASC 606-10, “ Revenues from Contracts with Customers. ” We identify a performance obligation as distinct if both of the following criteria are true: the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer and the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract. Determining the standalone selling price (“SSP”) and allocation of consideration from a contract to the individual performance obligations, and the appropriate timing of revenue recognition, is the result of significant qualitative and quantitative judgments. Management considers a variety of factors such as historical sales, usage rates, costs, and expected margin, which may vary over time depending upon the unique facts and circumstances related to each performance obligation in making these estimates. While changes in the allocation of the SSP between performance obligations will not affect the amount of total revenue recognized for a particular contract, any material changes could impact the timing of revenue recognition, which would have a material effect on our financial position and result of operations. This is because the contract consideration is allocated to each performance obligation, delivered or undelivered, at the inception of the contract based on the SSP of each distinct performance obligation. Clear Aligner We enter into contracts (“treatment plan(s)”) that involve multiple future performance obligations. Invisalign Full, Invisalign Teen, and Invisalign Assist products include optional additional aligners at no charge for a period of up to five years after initial shipment and Invisalign Go includes optional additional aligners at no charge for a period of up to two years after initial shipment. Invisalign Teen also includes up to six optional replacement aligners in the price of the product and may be ordered by the dental professional any time throughout treatment. Invisalign Lite includes one optional case refinement in the price of the product. Case refinement is a finishing tool used to adjust a patient’s teeth to the desired final position and may be elected by the dental professional at any time during treatment; however, it is generally ordered in the last stages of orthodontic treatment. We determined that our treatment plans comprise the following performance obligations that also represent distinct deliverables: initial aligners, additional aligners, case refinement, and replacement aligners. We elected to take the practical expedient to consider shipping and handling costs as activities to fulfill the performance obligation. We allocate revenue for each treatment plan based on each unit’s SSP and recognize the revenue over the manufacturing period, typically 1 to 3 days, as the aligners do not have an alternative use and we have enforceable rights to payment. As we collect most consideration upfront, we considered whether a significant financing component exists; however, as the delivery of the performance obligations are at the customer’s discretion, we concluded that no significant financing component exists. Scanner We sell intraoral scanners and computer-aided design/computer-aided manufacturing (“CAD/CAM”) services through both our direct sales force and distribution partners. The intraoral scanner sales price includes one year of warranty and unlimited scanning services. The customer may, for additional fees, also select extended warranty and unlimited scanning services for periods beyond the initial year. When intraoral scanners are sold with an unlimited scanning service agreement and/or extended warranty, we allocate revenue based on each element’s SSP. We estimate the SSP of each element, taking into consideration historical prices as well as our discounting strategies. Revenue is then recognized over time as the monthly services are rendered and upon shipment for the scanner, as that is when we deem the customer to have obtained control. Most consideration is collected upfront and in cases where there are payment plans, consideration is collected by the 1 year mark and therefore, there are no significant financing components. Warranties For both Clear Aligner and Scanner segments, we offer an assurance warranty which provides the customer assurance that the product will function as the parties intended because it complies with agreed-upon specifications, and thus is not treated as a separate performance obligation and will continue to be accrued in accordance with the Financial Accounting Standards Board (“FASB”) guidance on guarantees. Volume Discounts In certain situations, we offer promotions in which the discount will increase depending upon the volume purchased over time. We concluded that in these situations, the promotions can represent either variable consideration or options, depending upon the specifics of the promotion. In the event the promotion contains an option, the option is considered a material right and, therefore, included in the accounting for the initial arrangement. We estimate the average anticipated discount over the lifetime of the promotion or contract, and apply that discount to each unit as it is sold. On a quarterly basis, we review our estimates and, if needed, updates are made and changes are applied prospectively. Costs to Obtain a Contract We offer a variety of commission plans to our salesforce; each plan has multiple components. To match the costs to obtain a contract to the associated revenue, we evaluate the individual components and capitalize the eligible components, recognizing the costs over the treatment period. Unfulfilled Performance Obligations for Clear Aligners and Scanners Our unfilled performance obligations as of June 30, 2018 and the estimated revenue expected to be recognized in the future related to these performance obligations are $358.0 million . This includes performance obligations from the Clear Aligner segment, primarily the shipment of additional aligners, which are fulfilled over 1 to 5 years, and performance obligations from the iTero scanner segment, primarily contracted deliveries of additional scanners and support, which are fulfilled over 1 to 5 years. The estimate includes both product and service unfulfilled performance obligations and the time range reflects our best estimate of when we will transfer control to the customer and may change based on customer usage patterns, timing of shipments, readiness of customers’ facilities for installation, and manufacturing availability. Contract Balances The timing of revenue recognition results in deferred revenues being recognized on the Condensed Consolidated Balance Sheet. For both aligners and scanners, we usually collect the total consideration owed prior to all performance obligations being performed and payment terms vary from net 30 to net 90 days. Contract liabilities are recorded as deferred revenue balances, which are generated based upon timing of invoices and recognition patterns, not payments. If the revenue recognition exceeds the billing, the exceeded amount is considered unbilled receivable and a contract asset. Conversely, if the billing occurs prior to the revenue recognition, the amount is considered deferred revenue and a contract liability.
Investments in Privately Held Companies	Investments in Privately Held Companies Investments in privately held companies in which we can exercise significant influence but do not own a majority equity interest or otherwise control are accounted for under ASC 323, “ Investments—Equity Method and Joint Ventures. ” Equity securities qualified as equity method investments are reported on our Condensed Consolidated Balance Sheet as a single amount, and we record our share of their operating results within equity in losses of investee, net of tax, in our Condensed Consolidated Statement of Operations. Investments in privately held companies in which we can not exercise significant influence and do not own a majority equity interest or otherwise control are accounted for under ASC 321, “ Investments—Equity Securities. ” The equity securities without readily determinable fair values are recorded at cost and adjusted for impairments and observable price changes with a same or similar security from the same issuer (“Measurement Alternative”). Equity securities under ASC 321 are reported on our Condensed Consolidated Balance Sheet as other assets, and we record a change in carrying value of our equity securities, if any, in other income (expense), net in our Condensed Consolidated Statement of Operations. Equity securities are evaluated for impairment as events or circumstances indicate that there is an other-than-temporary loss in value. The decrease in value is recognized in the period the impairment occurs and recorded in other income (expense), net in the Condensed Consolidated Statement of Operations.
Recent Accounting Pronouncements	Recent Accounting Pronouncements (i) New Accounting Updates Recently Adopted In May 2014, the FASB released ASU 2014-09, “ Revenue from Contracts with Customers, ” (Topic 606) to supersede nearly all existing revenue recognition guidance under GAAP. The core principle of the standard is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for the goods or services. We adopted the guidance in the first quarter of fiscal year 2018 by applying the full retrospective method. The impact of adoption was primarily related to the Clear Aligner segment. Our disaggregation of revenue can be found in Note 14 “Segments and Geographical Information.” We elected to take the practical expedient to exclude from the transaction price all taxes assessed by a governmental authority. In preparation for adoption of the standard, we have reviewed and, where necessary, implemented additional key system functionalities and internal controls to enable the preparation of financial information. Prior periods have been retrospectively adjusted, and we recognized cumulative effect of adopting the guidance as an adjustment to our opening balance of retained earnings as of January 1, 2016. The adoption of ASU 2014-09 did not have a material impact on our Condensed Consolidated Statements of Operations, Condensed Consolidated Statements of Comprehensive Income or Condensed Consolidated Statements of Cash Flows for the historical periods presented in the Item 1 Financial Statements section. Consolidated Balance Sheet line items, which reflect the adoption of the ASU 2014-09 are as follows (in thousands): December 31, 2017 As Previously Reported Adjustment As Adjusted Asset Accounts: Accounts receivable, net $ 322,825 $ 1,364 $ 324,189 Deferred tax assets 50,059 (725 ) 49,334 Other assets 38,379 5,514 43,893 Liability and Stockholders’ Equity Accounts: Accrued liabilities $ 194,198 $ 1,364 $ 195,562 Deferred revenues 266,842 871 267,713 Retained earnings 263,356 3,918 267,274 In August 2016, the FASB issued ASU 2016-15, “Classification of Certain Cash Receipts and Cash Payments,” which clarifies the presentation and classification of certain cash receipts and cash payments in the statements of cash flows. The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2017. We adopted the standard in the first quarter of fiscal year 2018 on a retrospective basis, and it did not have an impact on our Condensed Consolidated Statements of Cash Flows. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows—Restricted Cash,” which provides guidance to address the classification and presentation of changes in restricted cash in the statements of cash flows . The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2017 on a retrospective basis. We adopted the guidance in the first quarter of fiscal year 2018 on a retrospective basis and presented the changes in the total of cash, cash equivalents, and restricted cash in the Condensed Consolidated Statements of Cash Flows. Condensed Consolidated Statement of Cash Flows line items, which reflect the adoption of the ASU 2016-18, are as follows (in thousands): Six Months Ended As Previously Reported Adjustment As Adjusted Cash Flows from Investing Activities Other investing activities $ 224 $ (3,164 ) $ (2,940 ) Net cash used in investing activities (108,554 ) (3,164 ) (111,718 ) Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash 3,613 27 3,640 Net decrease in cash, cash equivalents, and restricted cash (31,093 ) (3,137 ) (34,230 ) Cash, cash equivalents, and restricted cash at beginning of the period 389,275 3,744 393,019 Cash, cash equivalents, and restricted cash at end of the period $ 358,182 $ 607 $ 358,789 In May 2017, the FASB issued ASU 2017-09, “ Compensation — Stock Compensation (Topic 718): Scope of Modification Accounting,” to clarify when to account for a change to the terms or conditions of a share-based payment award as a modification. The amendments are effective for fiscal years and interim periods within those years beginning after December 15, 2017 on a prospective basis. We adopted the standard in the first quarter of fiscal year 2018 on a prospective basis which did not have an impact on our condensed consolidated financial statements and related disclosures. (ii) Recent Accounting Updates Not Yet Effective In February 2016, the 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. We plan to adopt the standard in the first quarter of fiscal year 2019 by electing the package of practical expedients available in the standard. We are in the process of evaluating changes to our systems, processes and controls in order to adopt the new standard in the first quarter of fiscal year 2019. While we are currently evaluating the impact of the adoption of this guidance on our consolidated financial statements, we expect the adoption will have a material increase in assets and liabilities on our consolidated balance sheet. 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. 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 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 are currently evaluating the impact of this guidance on our consolidated financial statements and related disclosures.

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	Consolidated Balance Sheet line items, which reflect the adoption of the ASU 2014-09 are as follows (in thousands): December 31, 2017 As Previously Reported Adjustment As Adjusted Asset Accounts: Accounts receivable, net $ 322,825 $ 1,364 $ 324,189 Deferred tax assets 50,059 (725 ) 49,334 Other assets 38,379 5,514 43,893 Liability and Stockholders’ Equity Accounts: Accrued liabilities $ 194,198 $ 1,364 $ 195,562 Deferred revenues 266,842 871 267,713 Retained earnings 263,356 3,918 267,274 Condensed Consolidated Statement of Cash Flows line items, which reflect the adoption of the ASU 2016-18, are as follows (in thousands): Six Months Ended As Previously Reported Adjustment As Adjusted Cash Flows from Investing Activities Other investing activities $ 224 $ (3,164 ) $ (2,940 ) Net cash used in investing activities (108,554 ) (3,164 ) (111,718 ) Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash 3,613 27 3,640 Net decrease in cash, cash equivalents, and restricted cash (31,093 ) (3,137 ) (34,230 ) Cash, cash equivalents, and restricted cash at beginning of the period 389,275 3,744 393,019 Cash, cash equivalents, and restricted cash at end of the period $ 358,182 $ 607 $ 358,789

Investments and Fair Value Me23

Investments and Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Short-Term And Long-Term Marketable Securities	As of June 30, 2018 and December 31, 2017 , 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 June 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 32,656 $ — $ — $ 32,656 Corporate bonds 84,246 1 (205 ) 84,042 U.S. government agency bonds 14,013 — (41 ) 13,972 U.S. government treasury bonds 32,953 3 (19 ) 32,937 Certificates of deposit 1,022 — — 1,022 Total marketable securities, short-term $ 164,890 $ 4 $ (265 ) $ 164,629 Long-term June 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government agency bonds $ 7,006 $ — $ (74 ) $ 6,932 Corporate bonds 1,128 1 — 1,129 Total marketable securities, long-term $ 8,134 $ 1 $ (74 ) $ 8,061 Short-term December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 58,503 $ — $ (1 ) $ 58,502 Corporate bonds 145,728 3 (174 ) 145,557 U.S. government agency bonds 3,013 — (7 ) 3,006 U.S. government treasury bonds 60,650 — (70 ) 60,580 Certificates of deposit 4,386 — — 4,386 Total marketable securities, short-term $ 272,280 $ 3 $ (252 ) $ 272,031 Long-term December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government agency bonds $ 15,023 $ — $ (68 ) $ 14,955 Corporate bonds 25,067 2 (76 ) 24,993 Total marketable securities, long-term $ 40,090 $ 2 $ (144 ) $ 39,948
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 June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 One year or less $ 164,629 $ 272,031 Due in greater than one year 8,061 39,948 Total available for sale short-term and long-term marketable securities $ 172,690 $ 311,979
Investments in privately held companies	Our investments in privately held companies as of June 30, 2018 and December 31, 2017 are as follows (in thousands): June 30, 2018 December 31, 2017 Equity securities under the equity method investment 1 $ 49,128 $ 54,606 Equity securities without readily determinable fair values 2 $ 4,862 $ —
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 June 30, 2018 and December 31, 2017 (in thousands): Description Balance as of June 30, 2018 Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 390,103 $ 390,103 $ — $ — Short-term investments: Commercial paper 32,656 — 32,656 — Corporate bonds 84,042 — 84,042 — U.S. government agency bonds 13,972 — 13,972 — U.S. government treasury bonds 32,937 32,937 — — Certificates of deposit 1,022 — 1,022 — Long-term investments: U.S. government agency bonds 6,932 — 6,932 — Corporate bonds 1,129 — 1,129 — Prepaid expenses and other current assets: Israeli funds 3,099 — 3,099 — $ 565,892 $ 423,040 $ 142,852 $ — Description Balance as of December 31, 2017 Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 253,155 $ 253,155 $ — $ — Commercial paper 7,246 — 7,246 — Corporate bonds 2,016 — 2,016 — Short-term investments: Commercial paper 58,502 — 58,502 — Corporate bonds 145,557 — 145,557 — U.S. government agency bonds 3,006 — 3,006 — U.S. government treasury bonds 60,580 60,580 — — Certificates of deposit 4,386 — 4,386 — Long-term investments: U.S. government agency bonds 14,955 — 14,955 — Corporate bonds 24,993 — 24,993 — Prepaid expenses and other current assets: Israeli funds 3,075 — 3,075 — Short-term notes receivable 4,476 — — 4,476 $ 581,947 $ 313,735 $ 263,736 $ 4,476
Notional value of derivative instruments	The following table presents the gross notional value of all our foreign exchange forward contracts outstanding as of June 30, 2018 (in thousands): June 30, 2018 Local Currency Amount Notional Contract Amount (USD) Euro €64,400 $ 75,322 Chinese Yuan ¥150,000 22,574 Canadian Dollar C$28,000 21,277 British Pound £13,000 17,159 Japanese Yen ¥1,513,000 13,670 Brazilian Real R$37,300 9,582 Australian Dollar A$7,300 5,390 $ 164,974

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Schedule of Inventories	Inventories consist of the following (in thousands): June 30, December 31, Raw materials $ 22,976 $ 12,721 Work in process 12,396 12,157 Finished goods 11,880 6,810 Total inventories $ 47,252 $ 31,688
Schedule of Other Assets	Other assets consist of the following (in thousands): June 30, December 31, Capitalized commissions $ 7,947 $ 5,515 Equity securities 4,862 — Security deposits 3,734 3,557 Loan receivable from equity investee — 30,000 Other long-term assets 2,759 4,821 Total other assets $ 19,302 $ 43,893
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): June 30, December 31, Accrued payroll and benefits $ 87,697 $ 103,004 Accrued expenses 36,776 27,318 Accrued fixed assets 12,889 11,362 Accrued customer credits 11,552 5,373 Accrued income taxes 7,764 12,405 Accrued warranty 7,286 5,929 Accrued professional fees 6,876 6,316 Accrued sales tax and value added tax 5,955 5,503 Accrued sales return reserve 1 5,554 1,364 Accrued sales rebate 3,772 11,209 Other accrued liabilities 10,633 5,779 Total accrued liabilities $ 196,754 $ 195,562 1 December 31, 2017 balance has been reclassified from accounts receivable, net to reflect the adoption of ASU 2014-09 ( Refer to Note 1 “Summary of Significant Accounting Policies” of the Notes to Condensed Consolidated Financial Statements for more information).
Schedule of Warranty Accrual	Warranty accrual as of June 30, 2018 and 2017 consists of the following activity (in thousands): Six Months Ended 2018 2017 Balance at beginning of period $ 5,929 $ 3,841 Charged to cost of revenues 5,728 3,690 Actual warranty expenditures (4,371 ) (2,503 ) Balance at end of period $ 7,286 $ 5,028
Schedule of Deferred Revenues	Deferred revenues consist of the following (in thousands): June 30, December 31, Deferred revenues - current $ 321,148 $ 267,713 Deferred revenues - long-term 1 7,625 4,588 1 Included in other long-term liabilities on our Condensed Consolidated Balance Sheet.

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Summary of Goodwill by Reportable Segment	The change in the carrying value of goodwill for the six months ended June 30, 2018 , all attributable to our Clear Aligner reporting unit, is as follows (in thousands): Total Balance as of December 31, 2017 $ 64,614 Adjustments 1 (434 ) Balance as of June 30, 2018 $ 64,180 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 Accumulated Amortization Accumulated Impairment Loss Net Carrying Trademarks 15 $ 7,100 $ (1,838 ) $ (4,179 ) $ 1,083 Existing technology 13 12,600 (4,986 ) (4,328 ) 3,286 Customer relationships 11 33,500 (15,612 ) (10,751 ) 7,137 Reacquired rights 3 7,500 (2,894 ) — 4,606 Patents 8 6,796 (1,919 ) — 4,877 Other 2 618 (480 ) — 138 Total intangible assets $ 68,114 $ (27,729 ) $ (19,258 ) $ 21,127 Weighted Average Amortization Period (in years) Gross Carrying Amount as of December 31, 2017 Accumulated Amortization Accumulated Impairment Loss Net Carrying Value as of December 31, 2017 Trademarks 15 $ 7,100 $ (1,769 ) $ (4,179 ) $ 1,152 Existing technology 13 12,600 (4,704 ) (4,328 ) 3,568 Customer relationships 11 33,500 (14,681 ) (10,751 ) 8,068 Reacquired rights 3 7,500 (1,356 ) — 6,144 Patents 8 6,798 (1,504 ) — 5,294 Other 2 618 (390 ) — 228 Total intangible assets $ 68,116 $ (24,404 ) $ (19,258 ) $ 24,454
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The total estimated annual future amortization expense for these acquired intangible assets as of June 30, 2018 is as follows (in thousands): Fiscal Year Ending December 31, Amortization Remainder of 2018 $ 3,149 2019 6,184 2020 3,855 2021 3,389 2022 2,116 Thereafter 2,434 Total $ 21,127

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Notes To Financial Statements [Abstract]
Schedule of Future Lease Payments	As of June 30, 2018 , minimum future lease payments for non-cancelable operating leases are as follows (in thousands): Fiscal Year Ending December 31, Operating Leases Remainder of 2018 $ 9,213 2019 17,350 2020 13,503 2021 11,827 2022 9,617 Thereafter 20,738 Total minimum future lease payments $ 82,248

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2018
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 and six months ended June 30, 2018 and 2017 is as follows (in thousands): Three Months Ended Six Months Ended 2018 2017 2018 2017 Cost of net revenues $ 900 $ 768 $ 1,781 $ 1,693 Selling, general and administrative 13,216 11,218 25,794 22,934 Research and development 2,774 2,259 5,145 4,430 Total stock-based compensation $ 16,890 $ 14,245 $ 32,720 $ 29,057
Stock Option Activity	Activity for the six months ended June 30, 2018 under the stock option plans is set forth below: Number of Shares Underlying Stock Options (in thousands) Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding as of December 31, 2017 75 $ 11.36 Exercised (61 ) 12.13 Cancelled or expired — — Outstanding as of June 30, 2018 14 $ 7.96 0.62 $ 4,651 Vested at June 30, 2018 14 $ 7.96 0.62 $ 4,651 Exercisable at June 30, 2018 14 $ 7.96 0.62 $ 4,651
Summary Of Restricted Stock Units	A summary for the six months ended June 30, 2018 is as follows: Shares Underlying RSUs (in thousands) Weighted Average Grant Date Fair Value Weighted Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Nonvested as of December 31, 2017 1,341 $ 82.30 Granted 214 256.85 Vested and released (491 ) 71.93 Forfeited (65 ) 98.99 Nonvested as of June 30, 2018 999 $ 123.73 1.44 $ 341,829
Summary Of Market-performance Based Restricted Stock Units	The following table summarizes the MSU performance for the six months ended June 30, 2018 : 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, 2017 428 $ 78.53 Granted 208 261.86 Vested and released (312 ) 62.41 Forfeited — — Nonvested as of June 30, 2018 324 $ 211.91 1.66 $ 110,922
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: Six Months Ended 2018 2017 Expected term (in years) 1.3 1.2 Expected volatility 35.7 % 26.1 % Risk-free interest rate 1.9 % 0.9 % Expected dividends — — Weighted average fair value at grant date $ 78.38 $ 26.09

Net Income Per Share (Tables)

Net Income Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
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 Six Months Ended 2018 2017 2018 2017 Numerator: Net income $ 106,105 $ 69,179 $ 201,971 $ 138,599 Denominator: Weighted-average common shares outstanding, basic 80,216 80,188 80,127 80,047 Dilutive effect of potential common stock 1,255 1,443 1,448 1,621 Total shares, diluted 81,471 81,631 81,575 81,668 Net income per share, basic $ 1.32 $ 0.86 $ 2.52 $ 1.73 Net income per share, diluted $ 1.30 $ 0.85 $ 2.48 $ 1.70

Segments and Geographical Inf29

Segments and Geographical Information (Tables)	6 Months Ended
	Jun. 30, 2018
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 Six Months Ended Net revenues 2018 2017 2018 2017 Clear Aligner $ 433,241 $ 321,036 $ 818,746 $ 603,435 Scanner 57,018 35,446 108,437 63,388 Total net revenues $ 490,259 $ 356,482 $ 927,183 $ 666,823 Gross profit Clear Aligner $ 331,612 $ 250,814 $ 628,588 $ 470,761 Scanner 33,970 20,103 64,402 35,781 Total gross profit $ 365,582 $ 270,917 $ 692,990 $ 506,542 Income from operations Clear Aligner $ 190,287 $ 133,916 $ 351,741 $ 248,650 Scanner 17,670 8,795 33,752 14,799 Unallocated corporate expenses (85,266 ) (59,142 ) (164,610 ) (118,207 ) Total income from operations $ 122,691 $ 83,569 $ 220,883 $ 145,242 Depreciation and amortization Clear Aligner $ 6,759 $ 5,600 $ 13,143 $ 9,963 Scanner 1,169 1,082 2,273 2,119 Unallocated corporate depreciation and amortization 4,704 2,194 8,650 4,661 Total depreciation and amortization $ 12,632 $ 8,876 $ 24,066 $ 16,743 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 Six Months Ended 2018 2017 2018 2017 Total segment income from operations $ 207,957 $ 142,711 $ 385,493 $ 263,449 Unallocated corporate expenses (85,266 ) (59,142 ) (164,610 ) (118,207 ) Total income from operations 122,691 83,569 220,883 145,242 Interest income 1,917 1,441 4,093 2,636 Other income (expense), net (7,099 ) 1,771 (6,922 ) 2,221 Net income before provision for income taxes and equity in losses of investee $ 117,509 $ 86,781 $ 218,054 $ 150,099
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 Six Months Ended 2018 2017 2018 2017 Net revenues 1 : United States $ 254,020 $ 207,021 $ 491,123 $ 390,294 The Netherlands 156,428 109,532 295,959 209,331 Other International 79,811 39,929 140,101 67,198 Total net revenues $ 490,259 $ 356,482 $ 927,183 $ 666,823 1 Net revenues are attributed to countries based on location of where revenue is recognized. Tangible long-lived assets are presented below by geographic area (in thousands): June 30, December 31, 2017 Long-lived assets 2 : The Netherlands $ 190,130 $ 143,673 United States 129,837 128,171 Costa Rica 61,609 30,738 Mexico 31,289 25,090 China 16,393 5,480 Other International 18,675 15,641 Total long-lived assets $ 447,933 $ 348,793 2 Long-lived assets are attributed to countries based on entity that owns the assets.

Summary of Significant Accoun30

Summary of Significant Accounting Policies - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation	$ 358
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue Recognition Period	1 day
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue Recognition Period	3 days

Summary of Significant Accoun31

Summary of Significant Accounting Policies - Balance sheet as adjusted (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 374,371	$ 324,189
Deferred tax assets	45,859	49,334
Other assets	19,302	43,893
Accrued liabilities	196,754	195,562
Deferred revenues	321,148	267,713
Retained earnings	$ 373,441	267,274
As Previously Reported | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net		322,825
Deferred tax assets		50,059
Other assets		38,379
Accrued liabilities		194,198
Deferred revenues		266,842
Retained earnings		263,356
Adjustment | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net		1,364
Deferred tax assets		(725)
Other assets		5,514
Accrued liabilities		1,364
Deferred revenues		871
Retained earnings		$ 3,918

Summary of Significant Accoun32

Summary of Significant Accounting Policies - Cash flow statement as adjusted (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Initial Application Period [Line Items]
Other investing activities	$ 668	$ (2,940)
Net cash used in investing activities	54,003	(111,718)
Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash	(1,923)	3,640
Net decrease in cash, cash equivalents, and restricted cash		(34,230)
Cash, cash equivalents, and restricted cash at beginning of the period	450,125	393,019
Cash, cash equivalents, and restricted cash at end of the period	$ 548,581	358,789
As Previously Reported
Initial Application Period [Line Items]
Other investing activities		224
Net cash used in investing activities		(108,554)
Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash		3,613
Net decrease in cash, cash equivalents, and restricted cash		(31,093)
Cash, cash equivalents, and restricted cash at beginning of the period		389,275
Cash, cash equivalents, and restricted cash at end of the period		358,182
Accounting Standards Update 2016-18 | Adjustment
Initial Application Period [Line Items]
Other investing activities		(3,164)
Net cash used in investing activities		(3,164)
Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash		27
Net decrease in cash, cash equivalents, and restricted cash		(3,137)
Cash, cash equivalents, and restricted cash at beginning of the period		3,744
Cash, cash equivalents, and restricted cash at end of the period		$ 607

Investments and Fair Value Me33

Investments and Fair Value Measurements Short-Term and Long-Term Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Total available for sale short-term and long-term marketable securities	$ 172,690	$ 311,979
Fair Value, Measurements, Recurring | Short-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	164,890	272,280
Gross Unrealized Gains	4	3
Gross Unrealized Losses	(265)	(252)
Total available for sale short-term and long-term marketable securities	164,629	272,031
Fair Value, Measurements, Recurring | Short-term Investments | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,656	58,503
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(1)
Total available for sale short-term and long-term marketable securities	32,656	58,502
Fair Value, Measurements, Recurring | Short-term Investments | Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	84,246	145,728
Gross Unrealized Gains	1	3
Gross Unrealized Losses	(205)	(174)
Total available for sale short-term and long-term marketable securities	84,042	145,557
Fair Value, Measurements, Recurring | Short-term Investments | U.S. government agency bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,013	3,013
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(41)	(7)
Total available for sale short-term and long-term marketable securities	13,972	3,006
Fair Value, Measurements, Recurring | Short-term Investments | U.S. government treasury bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,953	60,650
Gross Unrealized Gains	3	0
Gross Unrealized Losses	(19)	(70)
Total available for sale short-term and long-term marketable securities	32,937	60,580
Fair Value, Measurements, Recurring | Short-term Investments | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,022	4,386
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total available for sale short-term and long-term marketable securities	1,022	4,386
Fair Value, Measurements, Recurring | Long-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,134	40,090
Gross Unrealized Gains	1	2
Gross Unrealized Losses	(74)	(144)
Total available for sale short-term and long-term marketable securities	8,061	39,948
Fair Value, Measurements, Recurring | Long-term Investments | Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,128	25,067
Gross Unrealized Gains	1	2
Gross Unrealized Losses	0	(76)
Total available for sale short-term and long-term marketable securities	1,129	24,993
Fair Value, Measurements, Recurring | Long-term Investments | U.S. government agency bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,006	15,023
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(74)	(68)
Total available for sale short-term and long-term marketable securities	$ 6,932	$ 14,955

Investments and Fair Value Me34

Investments and Fair Value Measurements Additional Information (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
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	6 months

Investments and Fair Value Me35

Investments and Fair Value Measurements Available For Sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
One year or less	$ 164,629	$ 272,031
Due in greater than one year	8,061	39,948
Total available for sale short-term and long-term marketable securities	$ 172,690	$ 311,979

Investments and Fair Value Me36

Investments and Fair Value Measurements Investments in Privately Held Companies (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Equity securities under the equity method investment	$ 49,128	$ 54,606
Equity securities without readily determinable fair values	$ 4,862	$ 0

Investments and Fair Value Me37

Investments and Fair Value Measurements Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	$ 172,690	$ 311,979
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	565,892	581,947
Fair Value, Measurements, Recurring | Prepaid expenses and other current assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	3,099	3,075
Fair Value, Measurements, Recurring | Short-term notes receivable
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term notes receivable		4,476
Fair Value, Measurements, Recurring | Cash Equivalents | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	390,103	253,155
Fair Value, Measurements, Recurring | Cash Equivalents | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		7,246
Fair Value, Measurements, Recurring | Cash Equivalents | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		2,016
Fair Value, Measurements, Recurring | Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	164,629	272,031
Fair Value, Measurements, Recurring | Short-term Investments | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	32,656	58,502
Fair Value, Measurements, Recurring | Short-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	84,042	145,557
Fair Value, Measurements, Recurring | Short-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	13,972	3,006
Fair Value, Measurements, Recurring | Short-term Investments | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	32,937	60,580
Fair Value, Measurements, Recurring | Short-term Investments | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	1,022	4,386
Fair Value, Measurements, Recurring | Long-term Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	8,061	39,948
Fair Value, Measurements, Recurring | Long-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	1,129	24,993
Fair Value, Measurements, Recurring | Long-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	6,932	14,955
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	423,040	313,735
Fair Value, Measurements, Recurring | Level 1 | Prepaid expenses and other current assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	0	0
Fair Value, Measurements, Recurring | Level 1 | Short-term notes receivable
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term notes receivable		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	390,103	253,155
Fair Value, Measurements, Recurring | Level 1 | Cash Equivalents | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		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
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 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 | U.S. government treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	32,937	60,580
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	0
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	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	142,852	263,736
Fair Value, Measurements, Recurring | Level 2 | Prepaid expenses and other current assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	3,099	3,075
Fair Value, Measurements, Recurring | Level 2 | Short-term notes receivable
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term notes receivable		0
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		7,246
Fair Value, Measurements, Recurring | Level 2 | Cash Equivalents | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		2,016
Fair Value, Measurements, Recurring | Level 2 | Short-term Investments | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	32,656	58,502
Fair Value, Measurements, Recurring | Level 2 | Short-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	84,042	145,557
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	13,972	3,006
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 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	1,022	4,386
Fair Value, Measurements, Recurring | Level 2 | Long-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	1,129	24,993
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	6,932	14,955
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure	0	4,476
Fair Value, Measurements, Recurring | Level 3 | Prepaid expenses and other current assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	0	0
Fair Value, Measurements, Recurring | Level 3 | Short-term notes receivable
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term notes receivable		4,476
Fair Value, Measurements, Recurring | Level 3 | 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 3 | Cash Equivalents | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Fair Value, Measurements, Recurring | Level 3 | Cash Equivalents | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Fair Value, Measurements, Recurring | Level 3 | Short-term Investments | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Level 3 | Short-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Level 3 | 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 3 | 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 3 | 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 3 | Long-term Investments | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Level 3 | Long-term Investments | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	$ 0	$ 0

Investments and Fair Value Me38

Investments and Fair Value Measurements Derivative Notional Instruments (Details) - Foreign Exchange Forward € in Thousands, ¥ in Thousands, ¥ in Thousands, £ in Thousands, R$ in Thousands, $ in Thousands, $ in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2018JPY (¥)	Jun. 30, 2018CNY (¥)	Jun. 30, 2018USD ($)	Jun. 30, 2018EUR (€)	Jun. 30, 2018AUD ($)	Jun. 30, 2018BRL (R$)	Jun. 30, 2018CAD ($)	Jun. 30, 2018GBP (£)
Derivative [Line Items]
Gain on foreign currency forward contracts	$ 5,400	$ 5,400
Level 2 | Prepaid expenses and other current assets
Derivative [Line Items]
Notional amount					$ 164,974
Euro | Level 2 | Prepaid expenses and other current assets
Derivative [Line Items]
Notional amount					75,322	€ 64,400
Chinese Yuan | Level 2 | Prepaid expenses and other current assets
Derivative [Line Items]
Notional amount				¥ 150,000	22,574
Canadian Dollar | Level 2 | Prepaid expenses and other current assets
Derivative [Line Items]
Notional amount					21,277				$ 28,000
British Pound | Level 2 | Prepaid expenses and other current assets
Derivative [Line Items]
Notional amount					17,159					£ 13,000
Japanese Yen | Level 2 | Prepaid expenses and other current assets
Derivative [Line Items]
Notional amount			¥ 1,513,000		13,670
Brazilian Real | Level 2 | Prepaid expenses and other current assets
Derivative [Line Items]
Notional amount					9,582			R$ 37300
Australian Dollar | Level 2 | Prepaid expenses and other current assets
Derivative [Line Items]
Notional amount					$ 5,390		$ 7,300

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Disclosure Inventories [Abstract]
Raw materials	$ 22,976	$ 12,721
Work in process	12,396	12,157
Finished goods	11,880	6,810
Total inventories	$ 47,252	$ 31,688

Balance Sheet Components Other

Balance Sheet Components Other Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Notes To Financial Statements [Abstract]
Capitalized commissions	$ 7,947	$ 5,515
Equity securities	4,862	0
Security deposits	3,734	3,557
Loan receivable from equity investee	0	30,000
Other long-term assets	2,759	4,821
Total other assets	$ 19,302	$ 43,893

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Disclosure Accrued Liabilities [Abstract]
Accrued payroll and benefits	$ 87,697	$ 103,004
Accrued expenses	36,776	27,318
Accrued fixed assets	12,889	11,362
Accrued customer credits	11,552	5,373
Accrued income taxes	7,764	12,405
Accrued warranty	7,286	5,929
Accrued professional fees	6,876	6,316
Accrued sales tax and value added tax	5,955	5,503
Accrued sales return reserve	5,554	1,364
Accrued sales rebate	3,772	11,209
Other accrued liabilities	10,633	5,779
Total accrued liabilities	$ 196,754	$ 195,562

Warranty Accrual Activity (Deta

Warranty Accrual Activity (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 5,929	$ 3,841
Charged to cost of revenues	5,728	3,690
Actual warranty expenditures	(4,371)	(2,503)
Balance at end of period	$ 7,286	$ 5,028

Balance Sheet Components Deferr

Balance Sheet Components Deferred Revenues (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Notes To Financial Statements [Abstract]
Deferred revenues - current	$ 321,148	$ 267,713
Deferred revenues - long-term	$ 7,625	$ 4,588

Balance Sheet Components Narrat

Balance Sheet Components Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Revenue recognized	$ 490,259	$ 356,482	$ 927,183	$ 666,823
Deferred Revenue
Condensed Balance Sheet Statements, Captions [Line Items]
Deferred revenue	$ 102,000	$ 61,300	$ 187,700	$ 112,800

Equity Method Investments (Deta

Equity Method Investments (Details) - USD ($) $ in Thousands	Jul. 24, 2017	Jul. 25, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Feb. 07, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Equity method investments			$ 49,128		$ 49,128			$ 54,606
Net revenues			490,259	$ 356,482	927,183	$ 666,823
SDC
Schedule of Equity Method Investments [Line Items]
Ownership	19.00%	17.00%
Payments to acquire	$ 12,800	$ 46,700
Additional ownership acquired	2.00%
Due from related parties			11,800		11,800			$ 14,300
Net revenues			$ 8,600	$ 3,000	$ 13,900	$ 3,600
Loan receivable		$ 30,000					$ 30,000

Business Combinations (Details)

Business Combinations (Details) - Certain Distributors $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)
Business Acquisition [Line Items]
Cash consideration	$ 9.5
Net tangible liabilities	1.9
Intangibles acquired	8.2
Goodwill and intangible assets, net	$ 3.2

Goodwill and Intangible Asset47

Goodwill and Intangible Assets - Change in Carrying Value of Goodwill (Details) - Clear Aligner $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2017	$ 64,614
Adjustments	(434)
Balance as of June 30, 2018	$ 64,180

Goodwill and Intangible Asset48

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, beginning balance	$ 68,114	$ 68,116
Accumulated Amortization	(27,729)	(24,404)
Accumulated Impairment Loss	(19,258)	(19,258)
Net Carrying Value, ending balance	$ 21,127	$ 24,454
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	(1,838)	(1,769)
Accumulated Impairment Loss	(4,179)	(4,179)
Net Carrying Value, ending balance	$ 1,083	$ 1,152
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	(4,986)	(4,704)
Accumulated Impairment Loss	(4,328)	(4,328)
Net Carrying Value, ending balance	$ 3,286	$ 3,568
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	(15,612)	(14,681)
Accumulated Impairment Loss	(10,751)	(10,751)
Net Carrying Value, ending balance	$ 7,137	$ 8,068
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	(2,894)	(1,356)
Accumulated Impairment Loss	0	0
Net Carrying Value, ending balance	$ 4,606	$ 6,144
Patents
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (in years)	8 years	8 years
Gross Carrying Amount, beginning balance	$ 6,796	$ 6,798
Accumulated Amortization	(1,919)	(1,504)
Accumulated Impairment Loss	0	0
Net Carrying Value, ending balance	$ 4,877	$ 5,294
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	(480)	(390)
Accumulated Impairment Loss	0	0
Net Carrying Value, ending balance	$ 138	$ 228

Goodwill and Intangible Asset49

Goodwill and Intangible Assets - Total Estimated Annual Future Amortization Expense for Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Disclosure Total Estimated Annual Future Amortization Expense For Acquired Intangible Assets [Abstract]
Remainder of 2018	$ 3,149
2,019	6,184
2,020	3,855
2,021	3,389
2,022	2,116
Thereafter	2,434
Net Carrying Value, ending balance	$ 21,127	$ 24,454

Goodwill and Intangible Asset50

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill impairment					$ 0
Amortization	$ 1,500,000	$ 1,800,000	$ 3,000,000	$ 3,200,000

Credit Facilities - Additional

Credit Facilities - Additional Information (Details) - USD ($)	Feb. 27, 2018	Jun. 30, 2018	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%

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 M

Commitments and Contingencies Minimum Future Lease Payments for Non-Cancelable Leases (Details) - USD ($)	May 29, 2018	Feb. 07, 2018	Nov. 27, 2017	Jul. 24, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure Minimum Future Lease Payments For Non Cancelable Leases [Abstract]
Remainder of 2018					$ 9,213,000
2,019					17,350,000
2,020					13,503,000
2,021					11,827,000
2,022					9,617,000
Thereafter					20,738,000
Total minimum future lease payments					82,248,000
Other Commitments [Line Items]
Loan repayment from equity investee					$ 30,000,000	$ 0
Minimum purchase commitment	$ 425,900,000		$ 305,200,000
Purchase commitment, period	5 years		4 years
Maximum | SDC
Other Commitments [Line Items]
Loan facility				$ 30,000,000
Loan repayment from equity investee		$ 30,000,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)shares
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	6,066,597
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	647,363
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unamortized compensation cost | $	$ 98.3
Weighted average period of total unamortized cost (in years)	2 years 3 months 18 days
Market Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unamortized compensation cost | $	$ 48.6
Weighted average period of total unamortized cost (in years)	1 year 8 months 12 days
Market Performance Based Restricted Stock Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of granted market-performance based restricted stock units	2 years
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
Percentage of market-performance based restricted stock units eligible to vest over the vesting period	300.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unamortized compensation cost | $	$ 1.6
Weighted average period of total unamortized cost (in years)	4 months 24 days

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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 16,890	$ 14,245	$ 32,720	$ 29,057
Cost of net revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	900	768	1,781	1,693
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	13,216	11,218	25,794	22,934
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,774	$ 2,259	$ 5,145	$ 4,430

Stockholders' Equity - Activity

Stockholders' Equity - Activity Under Stock Option Plans (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Number of Shares Underlying Stock Options
Outstanding as of December 31, 2017 | shares	75
Exercised | shares	(61)
Cancelled or expired | shares	0
Outstanding as of June 30, 2018 | shares	14
Vested at June 30, 2018 | shares	14
Exercisable at June 30, 2018 | shares	14
Weighted Average Exercise Price per Share
Outstanding as of December 31, 2017 | $ / shares	$ 11.36
Exercised | $ / shares	12.13
Cancelled or expired | $ / shares	0
Outstanding as of June 30, 2018 | $ / shares	7.96
Vested at June 30, 2018 | $ / shares	7.96
Exercisable at June 30, 2018 | $ / shares	$ 7.96
Weighted Average Remaining Contractual Term
Outstanding as of June 30, 2018	7 months 13 days
Vested at June 30, 2018	7 months 13 days
Exercisable at June 30, 2018	7 months 13 days
Aggregate Intrinsic Value
Outstanding as of June 30, 2018 | $	$ 4,651
Vested at June 30, 2018 | $	4,651
Exercisable at June 30, 2018 | $	$ 4,651

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Nonvested Shares (Details) - Restricted Stock Units (RSUs) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Number of Shares Underlying RSUs
Nonvested as of December 31, 2017 | shares	1,341
Granted | shares	214
Vested and released | shares	(491)
Forfeited | shares	(65)
Nonvested as of June 30, 2018 | shares	999
Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2017 | $ / shares	$ 82.30
Granted | $ / shares	256.85
Vested and released | $ / shares	71.93
Forfeited | $ / shares	98.99
Nonvested as of June 30, 2018 | $ / shares	$ 123.73
Weighted Remaining Contractual Term (in years)
Nonvested as of June 30, 2018	1 year 5 months 9 days
Aggregate Intrinsic Value
Nonvested as of June 30, 2018 | $	$ 341,829

Stockholders' Equity - Summar58

Stockholders' Equity - Summary of MSU Performance (Details) - Market Performance Based Restricted Stock Units $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Number of Shares Underlying MSUs
Nonvested as of December 31, 2017 | shares	428
Granted | shares	208
Vested and released | shares	(312)
Forfeited | shares	0
Nonvested as of June 30, 2018 | shares	324
Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2017 | $ / shares	$ 78.53
Granted | $ / shares	261.86
Vested and released | $ / shares	62.41
Forfeited | $ / shares	0
Nonvested as of June 30, 2018 | $ / shares	$ 211.91
Weighted Average Remaining Contractual Term (in years)
Nonvested as of June 30, 2018	1 year 7 months 28 days
Aggregate Intrinsic Value
Nonvested as of June 30, 2018 | $	$ 110,922

Stockholders' Equity - Stock-59

Stockholders' Equity - Stock-based Compensation Employee Stock Purchase Plan (Details) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected term (in years)	1 year 3 months 18 days	1 year 2 months 12 days
Expected volatility	35.70%	26.10%
Risk-free interest rate	1.90%	0.90%
Expected dividends	0.00%	0.00%
Weighted average fair value at grant date (USD per Share)	$ 78.38	$ 26.09

Common Stock Repurchase Progr60

Common Stock Repurchase Programs - Additional Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	1 Months Ended
	Jul. 31, 2018	Feb. 28, 2018	Nov. 30, 2017	May 31, 2017	Jan. 31, 2017	May 23, 2018	Apr. 28, 2016
April 2014 Stock Repurchase Program
Share Repurchases [Line Items]
Accelerated share repurchase (shares)					40
Share repurchase price (in dollars per share)					$ 96.37
Repurchased					$ 3.8
April 2016 Repurchase Program
Share Repurchases [Line Items]
Accelerated share repurchase (shares)		400
Share repurchase price (in dollars per share)		$ 252.24
Repurchased		$ 100
Repurchase of common stock, common stock authorized							$ 300
2017 ASR
Share Repurchases [Line Items]
Accelerated share repurchase (shares)			200	400
Share repurchase price (in dollars per share)			$ 243.40
Price ($ per share)				$ 146.48
Repurchased			$ 50	$ 50
May 2018 Repurchase
Share Repurchases [Line Items]
Repurchase of common stock, common stock authorized						$ 600
Subsequent Event | April 2016 Repurchase Program
Share Repurchases [Line Items]
Accelerated share repurchase (shares)	300
Share repurchase price (in dollars per share)	$ 350.08
Repurchased	$ 100

Accounting for Income Taxes - A

Accounting for Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Taxes [Line Items]
Provision for income taxes		$ 7,703		$ 15,387	$ 10,605	$ 8,164
Effective income tax rate, continuing operations		6.60%		17.70%	4.90%	5.40%
Unrecognized tax benefits		$ 53,200	$ 47,700		$ 53,200		$ 47,700
Accrued penalties and interest		3,600			3,600
Unrecognized tax benefits that would impact effective tax rate		28,000			28,000
Extension period	12 years
Undistributed earnings of foreign subsidiaries			606,500				606,500
Amount of no longer indefinitely reinvested foreign earnings			591,900
Deferred tax liability due in event of foreign earnings being distributed			3,300
Amount of indefinitely reinvested foreign earnings			14,700				14,700
Additional income tax expense due to TCJA					$ 500		84,300
TCJA related to provisional transion tax liability			$ 73,900				73,900
TCJA related to remeasurement of certain deferred tax assets and liabilities							$ 10,400
Foreign Tax Authority
Income Taxes [Line Items]
Foreign income tax rate					30.00%	30.00%
Accounting Standards Update 2016-09
Income Taxes [Line Items]
Tax benefit		$ 16,600			$ 39,900

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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 106,105	$ 69,179	$ 201,971	$ 138,599
Weighted-average common shares outstanding, basic	80,216	80,188	80,127	80,047
Dilutive effect of potential common stock	1,255	1,443	1,448	1,621
Total shares, diluted	81,471	81,631	81,575	81,668
Net income per share, basic	$ 1.32	$ 0.86	$ 2.52	$ 1.73
Net income per share, diluted	$ 1.30	$ 0.85	$ 2.48	$ 1.70

Segments and Geographical Inf63

Segments and Geographical Information - Additional Information (Details)	6 Months Ended
	Jun. 30, 2018segment
Disclosure Segments And Geographical Information Additional Information [Abstract]
Number of reportable segments	2

Segments and Geographical Inf64

Segments and Geographical Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net revenues	$ 490,259	$ 356,482	$ 927,183	$ 666,823
Gross profit	365,582	270,917	692,990	506,542
Income from operations	122,691	83,569	220,883	145,242
Interest income	1,917	1,441	4,093	2,636
Depreciation and amortization	12,632	8,876	24,066	16,743
Other income (expense), net	(7,099)	1,771	(6,922)	2,221
Net income before provision for income taxes and equity in losses of investee	117,509	86,781	218,054	150,099
Operating segments
Segment Reporting Information [Line Items]
Income from operations	207,957	142,711	385,493	263,449
Clear Aligner
Segment Reporting Information [Line Items]
Net revenues	433,241	321,036	818,746	603,435
Gross profit	331,612	250,814	628,588	470,761
Income from operations	190,287	133,916	351,741	248,650
Depreciation and amortization	6,759	5,600	13,143	9,963
Scanner
Segment Reporting Information [Line Items]
Net revenues	57,018	35,446	108,437	63,388
Gross profit	33,970	20,103	64,402	35,781
Income from operations	17,670	8,795	33,752	14,799
Depreciation and amortization	1,169	1,082	2,273	2,119
Unallocated corporate expenses
Segment Reporting Information [Line Items]
Income from operations	(85,266)	(59,142)	(164,610)	(118,207)
Depreciation and amortization	$ 4,704	$ 2,194	$ 8,650	$ 4,661

Segments and Geographical Inf65

Segments and Geographical Information - Net Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net revenues	$ 490,259	$ 356,482	$ 927,183	$ 666,823
United States
Segment Reporting Information [Line Items]
Net revenues	254,020	207,021	491,123	390,294
The Netherlands
Segment Reporting Information [Line Items]
Net revenues	156,428	109,532	295,959	209,331
Other International
Segment Reporting Information [Line Items]
Net revenues	$ 79,811	$ 39,929	$ 140,101	$ 67,198

Segments and Geographical Inf66

Segments and Geographical Information - Long-Lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total long-lived assets	$ 447,933	$ 348,793
The Netherlands
Segment Reporting Information [Line Items]
Total long-lived assets	190,130	143,673
United States
Segment Reporting Information [Line Items]
Total long-lived assets	129,837	128,171
Costa Rica
Segment Reporting Information [Line Items]
Total long-lived assets	61,609	30,738
Mexico
Segment Reporting Information [Line Items]
Total long-lived assets	31,289	25,090
China
Segment Reporting Information [Line Items]
Total long-lived assets	16,393	5,480
Other International
Segment Reporting Information [Line Items]
Total long-lived assets	$ 18,675	$ 15,641