Business Combinations (Details) - USD ($) $ in Thousands	Apr. 01, 2020	Jun. 30, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill		$ 415,536	$ 63,924
Systems and Services
Business Acquisition [Line Items]
Goodwill		307,538	0
Clear Aligner
Business Acquisition [Line Items]
Goodwill		$ 107,998	$ 63,924
exocad Acquisition
Business Acquisition [Line Items]
Cash paid to exocad stockholders	$ 412,287
Cash paid to settle exocad's bank debt	17,691
Total purchase consideration paid	429,978
Goodwill	344,238
Identified intangible assets	118,700
Cash and cash equivalents	9,190
Deferred tax liabilities	(35,419)
Other assets (liabilities), net	(6,731)
Total	429,978
Intangible assets subject to amortization	118,700
Total intangible assets	118,700
exocad Acquisition | In Process Research and Development
Business Acquisition [Line Items]
Intangible assets not subject to amortization	400
exocad Acquisition | Existing technology
Business Acquisition [Line Items]
Identified intangible assets	$ 87,000
Weighted average amortization period	10 years
Intangible assets subject to amortization	$ 87,000
exocad Acquisition | Customer relationships
Business Acquisition [Line Items]
Identified intangible assets	$ 21,500
Weighted average amortization period	10 years
Intangible assets subject to amortization	$ 21,500
exocad Acquisition | Trade Names
Business Acquisition [Line Items]
Identified intangible assets	$ 9,800
Weighted average amortization period	7 years
Intangible assets subject to amortization	$ 9,800
exocad Acquisition | Systems and Services
Business Acquisition [Line Items]
Goodwill	300,700
exocad Acquisition | Clear Aligner
Business Acquisition [Line Items]
Goodwill	$ 43,500