Investments and Fair Value Measurements Additional Information (Details) $ in Thousands		3 Months Ended	6 Months Ended
	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 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 Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		3,000	12,700
SDC | Notes Receivable
Derivative [Line Items]
Accounts and Financing Receivable, after Allowance for Credit Loss						$ 54,200
exocad Acquisition
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		$ 1,000	$ 10,200
Forward Contracts | exocad Acquisition
Derivative [Line Items]
Notional amount | €					€ 376,000,000.0