Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2020
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	$ 53,238	$ 147,903
Unrealized Gains	1,151	1,815
Unrealized Losses	(5)	(38)
Fair Value	54,384	149,680
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	103,404
Unrealized Gains	771	1,288
Unrealized Losses	0	(20)
Fair Value	38,799	104,672
Corporate bonds
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	4,021	21,811
Unrealized Gains	77	350
Unrealized Losses	0	(6)
Fair Value	4,098	22,155
Government securities - U.S.
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	5,341	18,849
Unrealized Gains	110	155
Unrealized Losses	(5)	(5)
Fair Value	5,446	18,999
Other fixed-income securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	1,614	3,839
Unrealized Gains	23	22
Unrealized Losses	0	(7)
Fair Value	$ 1,637	$ 3,854

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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