Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in less than one year	$ 0
Due after one year through five years	0
Due after five years through ten years	0
Due after ten years	0
Held to maturity loans with maturity date, amortized cost, total	0
Held to maturity, amortized cost, total	691,404	$ 747,408
Fair Value
Due in less than one year	0
Due after one year through five years	0
Due after five years through ten years	0
Due after ten years	0
Held to maturity loans with maturity date, fair value, total	0
Held to maturity, fair value, total	537,218	617,741
Amortized Cost
Due in less than one year	6,157
Due after one year through five years	11,621
Due after five years through ten years	11,075
Due after ten years	32,303
Available for sale loans with maturity date, amortized cost, total	61,156
Available for sale, amortized cost, total	2,128,508	2,119,303
Fair Value
Due in less than one year	6,083
Due after one year through five years	11,365
Due after five years through ten years	10,938
Due after ten years	29,702
Available for sale loans with maturity date, fair value, total	58,088
Available for sale, fair value, total	1,841,845	1,871,742
Mortgage-backed securities and collateralized mortgage obligations of U.S. government-sponsored entities
Amortized Cost
Loans without single maturity date	691,404
Held to maturity, amortized cost, total		747,408
Fair Value
Loans without single maturity date	537,218
Held to maturity, fair value, total		617,741
Amortized Cost
Loans without single maturity date	1,593,306
Available for sale, amortized cost, total	1,593,306	1,561,197
Fair Value
Loans without single maturity date	1,326,639
Available for sale, fair value, total	1,326,639	1,338,653
Private mortgage-backed securities and collateralized mortgage obligations
Amortized Cost
Loans without single maturity date	0
Fair Value
Loans without single maturity date	0
Amortized Cost
Loans without single maturity date	139,089
Available for sale, amortized cost, total	139,089	179,148
Fair Value
Loans without single maturity date	125,187
Available for sale, fair value, total	125,187	166,387
Collateralized loan obligations
Amortized Cost
Loans without single maturity date	0
Fair Value
Loans without single maturity date	0
Amortized Cost
Loans without single maturity date	307,664
Available for sale, amortized cost, total	307,664	313,155
Fair Value
Loans without single maturity date	304,168
Available for sale, fair value, total	304,168	302,904
Other debt securities
Amortized Cost
Loans without single maturity date	0
Fair Value
Loans without single maturity date	0
Amortized Cost
Loans without single maturity date	27,293
Available for sale, amortized cost, total	27,293	22,640
Fair Value
Loans without single maturity date	27,763
Available for sale, fair value, total	$ 27,763	$ 22,410