Investment Securities - Schedule of Contractual Maturities of Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Available-for-sale securities
Due in one year or less, amortized cost	$ 150,539	$ 53,162	$ 99,892
Due in one to five years, amortized cost	168,856	132,348	139,623
Due in five to ten years, amortized cost	91,620	82,040	43,199
Due after ten years, amortized cost	23,834	18,705	64,419
Amortized Cost	4,320,843	3,979,814	4,315,723
Due in one year or less, fair value	150,627	52,945	99,525
Due in one to five years, fair value	164,650	123,985	130,036
Due in five to ten years, fair value	89,220	76,869	38,074
Due after ten years, fair value	21,809	15,782	54,855
Fair Value	3,912,232	3,502,915	3,611,835
Held-to-maturity securities
Held-to-maturity securities, due in one year or less, amortized cost	12,026	5,169	2,248
Held-to-maturity securities, due in one to five years, amortized cost	110,330	109,602	103,104
Held-to-maturity securities, due in five to ten years, amortized cost	84,580	99,700	106,042
Held-to-maturity securities, due after ten years, amortized cost	329,808	352,474	362,183
Amortized Cost	3,677,899	3,857,263	3,909,531
Less: Allowance for credit losses	(479)	(347)	(381)
Held-to-maturity securities, net of allowance for credit losses	3,677,420	3,856,916	3,909,150
Held-to-maturity securities, due in one year or less, fair value	11,883	5,142	2,241
Held-to-maturity securities, due in one to five years, fair value	108,416	105,835	96,546
Held-to-maturity securities, due in five to ten years, fair value	83,918	98,718	100,215
Held-to-maturity securities, due after ten years, fair value	271,954	283,506	270,722
Fair Value	3,121,820	3,215,468	3,057,959
Mortgage-backed
Available-for-sale securities
Mortgage-backed, without single maturity date, amortized cost	3,885,994	3,693,559	3,968,590
Mortgage-backed, without single maturity date, fair value	3,485,926	3,233,334	3,289,345
Held-to-maturity securities
Mortgage-backed, amortized cost	3,141,155	3,290,318	3,335,954
Mortgage-backed, fair value	$ 2,645,649	$ 2,722,267	$ 2,588,235