Summary of Significant Accounting Policies - Schedule of Changes in the Balance of Each Component of Accumulated Other Comprehensive Earnings (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Changes in the balance of each component of accumulated other comprehensive earnings
Beginning balance		$ 108,714			$ 108,714
Accounting Standards Update [Extensible List]				ASU 2016-13
Net current-period other comprehensive earnings (loss)	$ 15,177	(44,747)	$ 53,571	$ (13,031)	(29,570)	$ 40,540
Ending balance	79,144				79,144
Balance of securities for which an allowance for credit losses has been recognized in net earnings	321		1,752		321	1,752
Unrealized Gains and Losses on Available-for-Sale Securities
Changes in the balance of each component of accumulated other comprehensive earnings
Beginning balance	63,967	108,714	39,464	52,473	108,714	52,473
Other comprehensive earnings (loss) before reclassifications	15,601		53,733		(28,194)	41,853
Amounts reclassified from accumulated other comprehensive earnings	(424)		(162)		(1,376)	(1,313)
Ending balance	$ 79,144	63,967	$ 93,035	39,464	$ 79,144	93,035
Unrealized Gains and Losses on Available-for-Sale Securities | Cumulative Effect, Period of Adoption, Adjustment
Changes in the balance of each component of accumulated other comprehensive earnings
Beginning balance				22		$ 22
Accounting Standards Update [Extensible List]	ASU 2016-13		ASU 2016-13		ASU 2016-13	ASU 2016-13
Unrealized Gains and Losses on Available-for-Sale Securities | Cumulative Effect, Period of Adoption, Adjusted Balance
Changes in the balance of each component of accumulated other comprehensive earnings
Beginning balance	$ 63,967	108,714	$ 39,464	52,495	$ 108,714	$ 52,495
Ending balance		$ 63,967		$ 39,464