Investments - Available-for-sale securities (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,242,933
Gross Unrealized Gains	20
Gross Unrealized Losses	(2,688)
Fair Value	1,240,265
Aggregate fair value of available for sale securities	969,000
Available for sale securities in a continuous unrealized loss position	0
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	228,614
Gross Unrealized Losses	(2,232)
Fair Value	226,382
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,014,319
Gross Unrealized Gains	20
Gross Unrealized Losses	(456)
Fair Value	$ 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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