Investment Securities, Securities Held-to-Maturity (Details) - USD ($) $ in Thousands		Jun. 30, 2022		Dec. 31, 2021
Book values, estimated fair values and unrealized gains and losses of investments classified as held-to-maturity [Abstract]
Amortized cost		$ 868,383		$ 737,052
Gross unrealized gains		33		782
Gross unrealized losses		113,582		11,993
Fair value		754,834		725,841
Allowance for credit losses		393		0
Municipal Securities [Member]
Book values, estimated fair values and unrealized gains and losses of investments classified as held-to-maturity [Abstract]
Amortized cost		62,459		66,496
Gross unrealized gains		33		701
Gross unrealized losses		151		0
Fair value		62,341		67,197
Allowance for credit losses		393		0
Mortgage-backed Securities [Member]
Book values, estimated fair values and unrealized gains and losses of investments classified as held-to-maturity [Abstract]
Amortized cost	[1]	721,510		596,775
Gross unrealized gains	[1]	0		45
Gross unrealized losses	[1]	104,726		11,764
Fair value	[1]	616,784		585,056
Allowance for credit losses		0	[1]	0
Collateralized Mortgage Obligations [Member]
Book values, estimated fair values and unrealized gains and losses of investments classified as held-to-maturity [Abstract]
Amortized cost	[1]	84,414		73,781
Gross unrealized gains	[1]	0		36
Gross unrealized losses	[1]	8,705		229
Fair value	[1]	75,709		73,588
Allowance for credit losses		$ 0	[1]	$ 0

[1] All mortgage-backed securities and collateralized mortgage obligations were issued by an agency or government sponsored entity of the U.S. Government.