Subordinated Notes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2014	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Outstanding subordinated notes			$ 437,866	$ 437,392
Costs incurred in connection with the issuance of subordinated notes	$ 3,300	$ 1,300
4.85% subordinated notes maturing in June 2029
Debt Instrument [Line Items]
Proceeds, net of underwriting discount	296,700
5.00% subordinated notes maturing in June 2024
Debt Instrument [Line Items]
Proceeds, net of underwriting discount		139,100
Subordinated debt
Debt Instrument [Line Items]
Unamortized balances of costs for issuance of subordinated notes			$ 2,600
Subordinated debt | 4.85% subordinated notes maturing in June 2029
Debt Instrument [Line Items]
Principal amount of debt	$ 300,000
Stated interest rate	4.85%
Subordinated debt | 5.00% subordinated notes maturing in June 2024
Debt Instrument [Line Items]
Principal amount of debt		$ 140,000
Stated interest rate		5.00%