Marketable Securities Marketable Securities - Schedule of Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Total	$ 136,380	$ 54,384
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Less than 1 Year	1,270
1-5 Years	6,350
5-10 Years	1,272
Greater than 10 Years	0
Total	8,892	4,098
Government securities - U.S.
Debt Securities, Available-for-sale [Line Items]
Less than 1 Year	0
1-5 Years	25,965
5-10 Years	320
Greater than 10 Years	455
Total	26,740	5,446
Other fixed-income securities
Debt Securities, Available-for-sale [Line Items]
Less than 1 Year	51
1-5 Years	1,849
5-10 Years	0
Greater than 10 Years	0
Total	1,900	$ 1,637
Total
Debt Securities, Available-for-sale [Line Items]
Less than 1 Year	1,321
1-5 Years	34,164
5-10 Years	1,592
Greater than 10 Years	455
Total	$ 37,532