Summary of Significant Accounting Policies - Changes in the Balance of Each Component of Accumulated Other Comprehensive Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in the balance of each component of accumulated other comprehensive earnings (loss)
Beginning balance	$ (229,076)
Other comprehensive earnings (loss)	62,773	$ (278,902)	$ (58,888)
Ending balance	(166,303)	(229,076)
Balance of securities for which an allowance for credit losses has not been recognized in net earnings	1,224	1,693	124
Unrealized Gains and Losses on Available-for-Sale Securities
Changes in the balance of each component of accumulated other comprehensive earnings (loss)
Beginning balance	(229,076)	49,826	108,714
Other comprehensive earnings before reclassifications	59,922	(281,189)	(57,454)
Amounts reclassified from accumulated other comprehensive earnings	2,851	2,287	(1,434)
Other comprehensive earnings (loss)	62,773	(278,902)	(58,888)
Ending balance	$ (166,303)	$ (229,076)	$ 49,826