Fair Value Measurements - Valuation of Financial Instruments That are Marked-to-Market on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Assets:
Trading investments	$ 60,473	$ 54,481
Available-for-sale investments	2,283,262	2,411,622
Derivative instruments	$ 0	$ 0
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
Liabilities:
Derivative instruments	$ (116)	$ (370)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities	Other liabilities
Fair Value Measurements on a Recurring Basis
Assets:
Trading investments	$ 60,473	$ 54,481
Available-for-sale investments	2,283,262	2,411,622
Derivative instruments	0	0
Total earning assets	2,343,735	2,466,103
Liabilities:
Derivative instruments	(116)	(370)
Fair Value Measurements on a Recurring Basis | Level 1
Assets:
Trading investments	0	0
Available-for-sale investments	0	0
Derivative instruments	0	0
Total earning assets	0	0
Liabilities:
Derivative instruments	0	0
Fair Value Measurements on a Recurring Basis | Level 2
Assets:
Trading investments	0	0
Available-for-sale investments	2,280,155	2,411,622
Derivative instruments	0	0
Total earning assets	2,280,155	2,411,622
Liabilities:
Derivative instruments	(116)	(370)
Fair Value Measurements on a Recurring Basis | Level 3
Assets:
Trading investments	60,473	54,481
Available-for-sale investments	3,107	0
Derivative instruments	0	0
Total earning assets	63,580	54,481
Liabilities:
Derivative instruments	$ 0	$ 0