Accumulated Other Comprehensive Income (Loss) - Components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 6,309,331	$ 5,703,456	$ 5,984,612	$ 5,837,218
Other comprehensive loss	(101,938)	(205,723)	(16,303)	(510,267)
Ending balance	6,461,697	5,609,482	6,461,697	5,609,482
Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(640,734)	(365,653)	(694,815)	(85,703)
Net unrealized losses arising during the period	(43,618)	(192,858)	657	(474,219)
Amounts reclassified from AOCI	2,816	3,730	12,622	5,141
Other comprehensive loss	(40,802)	(189,128)	13,279	(469,078)
Ending balance	(681,536)	(554,781)	(681,536)	(554,781)
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(20,918)	(24,466)	(49,531)	257
Net unrealized losses arising during the period	(68,207)	(5,582)	(47,121)	(28,809)
Amounts reclassified from AOCI	14,320	(798)	21,847	(2,294)
Other comprehensive loss	(53,887)	(6,380)	(25,274)	(31,103)
Ending balance	(74,805)	(30,846)	(74,805)	(30,846)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(18,342)	(4,806)	(21,283)	(4,935)
Net unrealized losses arising during the period	(7,249)	(10,215)	(4,308)	(10,086)
Amounts reclassified from AOCI	0	0	0	0
Other comprehensive loss	(7,249)	(10,215)	(4,308)	(10,086)
Ending balance	(25,591)	(15,021)	(25,591)	(15,021)
AOCI, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(679,994)	(394,925)	(765,629)	(90,381)
Net unrealized losses arising during the period	(119,074)	(208,655)	(50,772)	(513,114)
Amounts reclassified from AOCI	17,136	2,932	34,469	2,847
Other comprehensive loss	(101,938)	(205,723)	(16,303)	(510,267)
Ending balance	$ (781,932)	$ (600,648)	$ (781,932)	$ (600,648)