Investments and Fair Value Measurements Additional Information (Details) $ in Thousands		3 Months Ended		9 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 EUR (€)	Apr. 30, 2019 USD ($)
Derivative [Line Items]
Original maturity of highly liquid investments included in cash and cash equivalents				40 months
Weighted average maturity	7 months
Equity Securities without Readily Determinable Fair Value, Amount	$ 5,900	$ 2,100		$ 2,100
Impairments on equity investments				3,787	$ 3,975
Derivative gains (losses)		$ (12,100)	$ 10,100	600	$ 10,500
SDC | Notes Receivable
Derivative [Line Items]
Accounts and Financing Receivable, after Allowance for Credit Loss							$ 54,200
exocad Acquisition
Derivative [Line Items]
Derivative gains (losses)				$ (10,200)
Forward Contracts | exocad Acquisition
Derivative [Line Items]
Notional amount | €						€ 376,000,000.0