Investments and Fair Value of Financial Instruments - Marketable Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value	$ 28,091	$ 7,875
Less than 12 months: Gross Unrealized Losses	(21)	(3)
12 Months of more: Fair Value	0	0
12 months or more: Gross Unrealized Losses	0	0
Total: Fair Value	28,091	7,875
Total: Gross Unrealized Losses	(21)	(3)
U.S. states and municipalities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value	3,426
Less than 12 months: Gross Unrealized Losses	(1)
12 Months of more: Fair Value	0
12 months or more: Gross Unrealized Losses	0
Total: Fair Value	3,426
Total: Gross Unrealized Losses	(1)
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value	24,665	7,875
Less than 12 months: Gross Unrealized Losses	(20)	(3)
12 Months of more: Fair Value	0	0
12 months or more: Gross Unrealized Losses	0	0
Total: Fair Value	24,665	7,875
Total: Gross Unrealized Losses	$ (20)	$ (3)