Investments - Schedule of Investments Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Investments available for sale
Amortized Cost	$ 5,075,982	$ 4,897,607
Unrealized Gains	242	98,747
Unrealized Losses	(491,380)	(33,467)
Fair Value	4,584,844	4,962,887
U.S. Treasury securities
Investments available for sale
Amortized Cost	566,466	447,926
Unrealized Gains	2	3,833
Unrealized Losses	(30,832)	(2,966)
Fair Value	535,636	448,793
U.S. agency securities
Investments available for sale
Amortized Cost	0	5,501
Unrealized Gains	0	3
Unrealized Losses	0	0
Fair Value	0	5,504
U.S. agency mortgage-backed securities
Investments available for sale
Amortized Cost	879,028	1,005,611
Unrealized Gains	0	13,365
Unrealized Losses	(126,792)	(10,113)
Fair Value	752,236	1,008,863
Municipal debt securities
Investments available for sale
Amortized Cost	627,772	598,764
Unrealized Gains	95	30,122
Unrealized Losses	(68,083)	(1,287)
Fair Value	559,784	627,599
Non-U.S. government securities
Investments available for sale
Amortized Cost	70,126	77,366
Unrealized Gains	0	3,232
Unrealized Losses	(9,292)	(855)
Fair Value	60,834	79,743
Corporate debt securities
Investments available for sale
Amortized Cost	1,501,150	1,428,645
Unrealized Gains	7	36,067
Unrealized Losses	(155,888)	(9,465)
Fair Value	1,345,269	1,455,247
Residential and commercial mortgage securities
Investments available for sale
Amortized Cost	586,771	541,638
Unrealized Gains	123	10,452
Unrealized Losses	(63,286)	(6,667)
Fair Value	523,608	545,423
Asset-backed securities
Investments available for sale
Amortized Cost	645,522	582,144
Unrealized Gains	15	1,673
Unrealized Losses	(37,207)	(2,114)
Fair Value	608,330	581,703
Money market funds
Investments available for sale
Amortized Cost	199,147	210,012
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 199,147	$ 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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