Investments - Short-term Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Marketable Securities [Line Items]
Adjusted Cost	$ 210,183	$ 72,859
Unrealized Gains	5	7
Unrealized Losses	(10)	(2)
Fair Value	210,178	72,864
Corporate bonds
Marketable Securities [Line Items]
Adjusted Cost	162,484	55,224
Unrealized Gains	5	5
Unrealized Losses	(9)	(2)
Fair Value	162,480	55,227
Government bonds
Marketable Securities [Line Items]
Adjusted Cost	29,859	14,121
Unrealized Gains	0	2
Unrealized Losses	(1)	0
Fair Value	29,858	14,123
Asset-backed bonds
Marketable Securities [Line Items]
Adjusted Cost	17,840	3,514
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 17,840	$ 3,514

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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