Fair Value of Financial Instruments - Valuation Techniques and Significant Unobservable Inputs (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net change in unrealized (loss) gain on private company investments	$ (670)	$ 19
Minimum | Relief from royalty | Significant Unobservable Inputs (Level 3) | Royalty rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input Value(s)	0.0025
Maximum | Relief from royalty | Significant Unobservable Inputs (Level 3) | Royalty rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input Value(s)	0.020
Private Company Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net change in unrealized (loss) gain on private company investments	$ 0	$ 100