Investment Securities, Securities Held-to-Maturity (Details) - USD ($) $ in Thousands		Mar. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Book values, estimated fair values and unrealized gains and losses of investments classified as held-to-maturity [Abstract]
Amortized cost		$ 850,387		$ 845,346
Gross unrealized gains		157		78
Gross unrealized losses		144,635		157,031
Fair value		705,909		688,393
Allowance for credit losses		393		393		$ 393
Municipal Securities [Member]
Book values, estimated fair values and unrealized gains and losses of investments classified as held-to-maturity [Abstract]
Amortized cost		76,260		62,302
Gross unrealized gains		98		49
Gross unrealized losses		96		209
Fair value		76,262		62,142
Allowance for credit losses		393		393		393
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]	695,083		702,858
Gross unrealized gains	[1]	59		29
Gross unrealized losses	[1]	130,405		141,121
Fair value	[1]	564,737		561,766
Allowance for credit losses		0	[1]	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]	79,044		80,186
Gross unrealized gains	[1]	0		0
Gross unrealized losses	[1]	14,134		15,701
Fair value	[1]	64,910		64,485
Allowance for credit losses		$ 0	[1]	$ 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.