Equity Method Investments	12 Months Ended
Dec. 31, 2017
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 Consolidated Balance Sheet under equity method investments, and we record our proportional share of SDC's income (losses) within equity in losses of investee, net of tax, in our 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 December 31, 2017 and 2016, the balance of our equity method investments was $54.6 million and $45.1 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 after eliminating outstanding intercompany transactions. As of December 31, 2017 and 2016, the balance of accounts receivable due from SDC was $14.3 million and $0.1 million, respectively. For the year ended December 31, 2017 and 2016, net revenues recognized from SDC were $24.1 million and $0.2 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. As of December 31, 2017, $30.0 million of advances under the Loan Agreement were outstanding and no outstanding advances as of December 31, 2016. 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 9 "Commitments and Contingencies" of the Notes to Consolidated Financial Statements for information on the Loan and Security Agreement with SDC). In February 2018, we received a communication on behalf of SDC Financial LLC, SmileDirectClub LLC, and the Members of SDC Financial LLC other than Align (collectively, the "SDC Entities") alleging that the launch and operation of our Invisalign store pilot program constitutes a breach of non-compete provisions applicable to the members of SDC Financial LLC, including Align. As a result of this alleged breach, SDC Financial LLC has notified Align that its members (other than Align) seek to exercise a right to repurchase all of Align’s SDC Financial LLC membership interests for a purchase price equal to the current capital account balance of Align. The SDC Entities also allege that Align has breached confidentiality provisions applicable to the SDC Financial LLC members and demands that Align cease all activities related to the Invisalign store pilot project, close existing Invisalign stores and cease using SDC’s confidential information. Align disputes the allegations that it has breached its obligations to the SDC Entities, including the allegation that the SDC Entities are entitled to exercise a repurchase right. Pursuant to the parties’ agreement, the dispute will be arbitrated if it is not resolved through negotiations. We are currently evaluating the potential impact that this could have on our consolidated financial statements.

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 Consolidated Balance Sheet under equity method investments, and we record our proportional share of SDC's income (losses) within equity in losses of investee, net of tax, in our 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 December 31, 2017 and 2016, the balance of our equity method investments was $54.6 million and $45.1 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 after eliminating outstanding intercompany transactions. As of December 31, 2017 and 2016, the balance of accounts receivable due from SDC was $14.3 million and $0.1 million, respectively. For the year ended December 31, 2017 and 2016, net revenues recognized from SDC were $24.1 million and $0.2 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. As of December 31, 2017, $30.0 million of advances under the Loan Agreement were outstanding and no outstanding advances as of December 31, 2016. 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 9 "Commitments and Contingencies" of the Notes to Consolidated Financial Statements for information on the Loan and Security Agreement with SDC).

In February 2018, we received a communication on behalf of SDC Financial LLC, SmileDirectClub LLC, and the Members of SDC Financial LLC other than Align (collectively, the "SDC Entities") alleging that the launch and operation of our Invisalign store pilot program constitutes a breach of non-compete provisions applicable to the members of SDC Financial LLC, including Align. As a result of this alleged breach, SDC Financial LLC has notified Align that its members (other than Align) seek to exercise a right to repurchase all of Align’s SDC Financial LLC membership interests for a purchase price equal to the current capital account balance of Align. The SDC Entities also allege that Align has breached confidentiality provisions applicable to the SDC Financial LLC members and demands that Align cease all activities related to the Invisalign store pilot project, close existing Invisalign stores and cease using SDC’s confidential information. Align disputes the allegations that it has breached its obligations to the SDC Entities, including the allegation that the SDC Entities are entitled to exercise a repurchase right. Pursuant to the parties’ agreement, the dispute will be arbitrated if it is not resolved through negotiations. We are currently evaluating the potential impact that this could have on our consolidated financial statements.