Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	$ 134,688	$ 147,903
Unrealized Gains	1,486	1,815
Unrealized Losses	(473)	(38)
Fair Value	135,701	149,680
Mutual and money market funds
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	90,907	103,404
Unrealized Gains	1,171	1,288
Unrealized Losses	(346)	(20)
Fair Value	91,732	104,672
Corporate bonds
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	22,853	21,811
Unrealized Gains	224	350
Unrealized Losses	(21)	(6)
Fair Value	23,056	22,155
Government securities - U.S.
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	17,873	18,849
Unrealized Gains	78	155
Unrealized Losses	(98)	(5)
Fair Value	17,853	18,999
Other fixed-income securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Adjusted Cost	3,055	3,839
Unrealized Gains	13	22
Unrealized Losses	(8)	(7)
Fair Value	$ 3,060	$ 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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