Accumulated Other Comprehensive Income (Loss) - Components of AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 5,984,612	$ 5,837,218	$ 5,269,175
Other comprehensive income (loss)	145,033	(675,248)	(134,706)
Ending balance	6,950,834	5,984,612	5,837,218
Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(694,815)	(85,703)	52,247
Net unrealized gains (losses) arising during the period	76,930	(620,870)	(136,846)
Amounts reclassified from AOCI	16,004	11,758	(1,104)
Other comprehensive income (loss)	92,934	(609,112)	(137,950)
Ending balance	(601,881)	(694,815)	(85,703)
Cash Flow Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(49,531)	257	(1,230)
Net unrealized gains (losses) arising during the period	(4,277)	(52,623)	866
Amounts reclassified from AOCI	56,432	2,835	621
Other comprehensive income (loss)	52,155	(49,788)	1,487
Ending balance	2,624	(49,531)	257
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(21,283)	(4,935)	(6,692)
Net unrealized gains (losses) arising during the period	(56)	(16,348)	1,757
Amounts reclassified from AOCI	0	0	0
Other comprehensive income (loss)	(56)	(16,348)	1,757
Ending balance	(21,339)	(21,283)	(4,935)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(765,629)	(90,381)	44,325
Net unrealized gains (losses) arising during the period	72,597	(689,841)	(134,223)
Amounts reclassified from AOCI	72,436	14,593	(483)
Other comprehensive income (loss)	145,033	(675,248)	(134,706)
Ending balance	$ (620,596)	$ (765,629)	$ (90,381)