Marketable Securities Marketable Securities - Schedule of Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Total	$ 148,467	$ 54,384
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Less than 1 Year	4,355
1-5 Years	14,274
5-10 Years	1,786
Greater than 10 Years	0
Total	20,415	4,098
Government securities - U.S.
Debt Securities, Available-for-sale [Line Items]
Less than 1 Year	0
1-5 Years	17,749
5-10 Years	739
Greater than 10 Years	1,728
Total	20,216	5,446
Other fixed-income securities
Debt Securities, Available-for-sale [Line Items]
Less than 1 Year	50
1-5 Years	3,600
5-10 Years	0
Greater than 10 Years	0
Total	3,650	$ 1,637
Total
Debt Securities, Available-for-sale [Line Items]
Less than 1 Year	4,405
1-5 Years	35,623
5-10 Years	2,525
Greater than 10 Years	1,728
Total	$ 44,281