Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Jun. 30, 2020
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	$ 53,238	$ 135,035
Unrealized Gains	1,151	1,354
Unrealized Losses	(5)	(9)
Fair Value	54,384	136,380
Equity securities
Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]
Adjusted Cost	4,234
Unrealized Gains	170
Unrealized Losses	0
Fair Value	4,404
Money market and mutual funds
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	38,028	98,024
Unrealized Gains	771	824
Unrealized Losses	0	0
Fair Value	38,799	98,848
Corporate bonds
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	4,021	8,720
Unrealized Gains	77	180
Unrealized Losses	0	(8)
Fair Value	4,098	8,892
Government securities - U.S.
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	5,341	26,424
Unrealized Gains	110	317
Unrealized Losses	(5)	(1)
Fair Value	5,446	26,740
Other fixed-income securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	1,614	1,867
Unrealized Gains	23	33
Unrealized Losses	0	0
Fair Value	$ 1,637	$ 1,900

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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