Investments - Available-for-sale securities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 816,976	$ 1,242,933
Gross Unrealized Gains		20
Gross Unrealized Losses	(17,748)	(2,688)
Fair Value	799,228	1,240,265
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	251,827	228,614
Gross Unrealized Losses	(6,906)	(2,232)
Fair Value	244,921	226,382
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	565,149	1,014,319
Gross Unrealized Gains		20
Gross Unrealized Losses	(10,842)	(456)
Fair Value	$ 554,307	$ 1,013,883

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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Amortized cost of 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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