Goodwill and Intangible Assets - Change in Carrying Value of Goodwill (Details) $ in Thousands	6 Months Ended
Jun. 30, 2020 USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2019	$ 63,924
Additions from exocad acquisition	344,238
Adjustments	7,374
Balance as of June 30, 2020	415,536
Clear Aligner
Goodwill [Roll Forward]
Balance as of December 31, 2019	63,924
Additions from exocad acquisition	43,500
Adjustments	574
Balance as of June 30, 2020	107,998
Systems and Services
Goodwill [Roll Forward]
Balance as of December 31, 2019	0
Additions from exocad acquisition	300,738
Adjustments	6,800
Balance as of June 30, 2020	$ 307,538

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of increase (decrease) from foreign currency translation adjustments and purchase accounting adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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