Investment Securities - Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Amortized Cost
Due in one year or less	$ 2,822	$ 6,954
Due after one through five years	11,694	5,097
Due after five through ten years	169,729	120,460
Due after ten years	1,480,472	1,464,460
Total debt securities with a single maturity date	1,664,717	1,596,971
Amortized Cost	2,273,347	2,268,655
Fair Value
Due in one year or less	2,809	6,965
Due after one through five years	11,265	5,309
Due after five through ten years	161,211	126,816
Due after ten years	1,293,103	1,537,856
Total debt securities with a single maturity date	1,468,388	1,676,946
Total Investment Securities	1,976,661	2,344,551
Amortized Cost
Due in one year or less	13,697	6,971
Due after one through five years	80,697	30,272
Due after five through ten years	147,078	177,203
Due after ten years	1,269,826	1,215,812
Total debt securities with a single maturity date	1,511,298	1,430,258
Amortized Cost	2,287,372	2,180,047
Fair Value
Due in one year or less	13,749	6,995
Due after one through five years	76,453	31,946
Due after five through ten years	135,027	180,129
Due after ten years	1,020,477	1,231,568
Total debt securities with a single maturity date	1,245,706	1,450,638
Total Investment Securities	1,907,865	2,202,503
U.S. Government-sponsored mortgage-backed securities
Amortized Cost
Without single maturity date	608,630	671,684
Amortized Cost	608,630	671,684
Fair Value
Without single maturity date	508,273	667,605
Total Investment Securities	508,273	667,605
Amortized Cost
Without single maturity date	776,074	749,789
Amortized Cost	776,074	749,789
Fair Value
Without single maturity date	662,159	751,865
Total Investment Securities	$ 662,159	$ 751,865