Investments - Schedule of Investments Available for Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Investments available for sale
Amortized Cost	$ 4,952,466	$ 4,897,607
Unrealized Gains	3,276	98,747
Unrealized Losses	(335,402)	(33,467)
Fair Value	4,620,340	4,962,887
U.S. Treasury securities
Investments available for sale
Amortized Cost	489,448	447,926
Unrealized Gains	358	3,833
Unrealized Losses	(19,660)	(2,966)
Fair Value	470,146	448,793
U.S. agency securities
Investments available for sale
Amortized Cost	2,000	5,501
Unrealized Gains	0	3
Unrealized Losses	0	0
Fair Value	2,000	5,504
U.S. agency mortgage-backed securities
Investments available for sale
Amortized Cost	867,198	1,005,611
Unrealized Gains	21	13,365
Unrealized Losses	(83,781)	(10,113)
Fair Value	783,438	1,008,863
Municipal debt securities
Investments available for sale
Amortized Cost	581,406	598,764
Unrealized Gains	2,158	30,122
Unrealized Losses	(42,792)	(1,287)
Fair Value	540,772	627,599
Non-U.S. government securities
Investments available for sale
Amortized Cost	71,378	77,366
Unrealized Gains	265	3,232
Unrealized Losses	(6,508)	(855)
Fair Value	65,135	79,743
Corporate debt securities
Investments available for sale
Amortized Cost	1,463,318	1,428,645
Unrealized Gains	361	36,067
Unrealized Losses	(109,569)	(9,465)
Fair Value	1,354,110	1,455,247
Residential and commercial mortgage securities
Investments available for sale
Amortized Cost	591,239	541,638
Unrealized Gains	87	10,452
Unrealized Losses	(45,327)	(6,667)
Fair Value	545,999	545,423
Asset-backed securities
Investments available for sale
Amortized Cost	645,854	582,144
Unrealized Gains	26	1,673
Unrealized Losses	(27,765)	(2,114)
Fair Value	618,115	581,703
Money market funds
Investments available for sale
Amortized Cost	240,625	210,012
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 240,625	$ 210,012

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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-SubTopic 10
-Section 50
-Paragraph 2
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Amount, before tax, of unrealized loss 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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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and 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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