Investment Securities Schedule of Amortized Cost and Fair Values of Debt Securities by Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 234,224
Due from one year to five years	90,789
Due from five years to ten years	545,358
Due after ten years	1,037,270
Amortized cost, before securities without debt maturities	1,907,641
Amortized Cost	2,916,610
Estimated Fair Value
Due in one year or less	229,237
Due from one year to five years	87,328
Due from five years to ten years	494,049
Due after ten years	889,310
Available for sale securities, debt maturities, before securities without single maturities	1,699,924
Estimated Fair Value	2,572,721	$ 2,646,767
Amortized Cost
Due in one year or less	0
Due from one year to five years	0
Due from five years to ten years	0
Due after ten years	0
Debt securities, held-to-maturity, maturity, allocated and single maturity date, amortized cost, total	0
Amortized Cost, Held to Maturity	1,294,613	1,321,256
Estimated Fair Value
Due in one year or less	0
Due from one year to five years	0
Due from five years to ten years	0
Due after ten years	0
Debt securities, held-to-maturity, maturity, Allocated and single maturity date, fair value	0
Estimated Fair Value, Held to Maturity	1,086,692	1,125,049
Mortgage-Backed Securities [Member]
Amortized Cost
Available-for-sale securities, amortized cost without single maturity date	233,807
Amortized Cost	233,807	242,527
Estimated Fair Value
Available-for-sale securities, debt maturities, without single maturity date, fair value	204,888
Estimated Fair Value	204,888	212,698
Amortized Cost
Debt securities, held-to-maturity, maturity, without single maturity date, amortized cost	431,704
Amortized Cost, Held to Maturity	431,704	457,325
Estimated Fair Value
Debt securities, held-to-maturity, maturity, without single maturity date, fair value	375,590
Estimated Fair Value, Held to Maturity	375,590	399,845
Commercial Mortgage Backed Securities [Member]
Amortized Cost
Available-for-sale securities, amortized cost without single maturity date	640,928
Amortized Cost	640,928	631,604
Estimated Fair Value
Available-for-sale securities, debt maturities, without single maturity date, fair value	547,451
Estimated Fair Value	547,451	552,522
Amortized Cost
Debt securities, held-to-maturity, maturity, without single maturity date, amortized cost	862,909
Amortized Cost, Held to Maturity	862,909	863,931
Estimated Fair Value
Debt securities, held-to-maturity, maturity, without single maturity date, fair value	711,102
Estimated Fair Value, Held to Maturity	711,102	725,204
Collateralized Mortgage Obligations [Member]
Amortized Cost
Available-for-sale securities, amortized cost without single maturity date	134,234
Amortized Cost	134,234	147,155
Estimated Fair Value
Available-for-sale securities, debt maturities, without single maturity date, fair value	120,458
Estimated Fair Value	120,458	$ 134,033
Amortized Cost
Debt securities, held-to-maturity, maturity, without single maturity date, amortized cost	0
Estimated Fair Value
Debt securities, held-to-maturity, maturity, without single maturity date, fair value	$ 0