Short-Term Borrowings and Long-Term Debt - Summary of Long-Term Borrowings (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	May 06, 2021	Jan. 31, 2014
Schedule Of Borrowings [Line Items]
Long-term debt		$ 859,147	$ 931,442
Repayments of long-term debt		75,000	0	$ 111,000
Senior Unsecured Credit-Linked Notes, Due 2024
Schedule Of Borrowings [Line Items]
Senior unsecured credit-linked notes		199,499	272,492
Repayments of long-term debt	$ 75,000
5.75% Subordinated Notes, Due 2026
Schedule Of Borrowings [Line Items]
Trust preferred securities issued		174,457	174,196
Interest rate						5.25%
4.00% Subordinated Notes, Due 2031
Schedule Of Borrowings [Line Items]
Trust preferred securities issued		371,785	371,348
Interest rate					4.00%
Floating Rate Subordinated Debentures, Due 2032 to 2036
Schedule Of Borrowings [Line Items]
Trust preferred securities issued		$ 113,406	$ 113,406