(11) Employee Benefits (Details - Fair value of plan assets) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 18,768	$ 26,098	$ 18,165
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	7,848	10,472
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	10,920	15,626
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Company Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		7,848	10,472
Company Common Stock [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	7,848	10,472
Company Common Stock [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	0	0
Company Common Stock [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Large Cap Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2,037	2,933
Large Cap Value [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Large Cap Value [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	2,037	2,933
Large Cap Value [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Mid Cap Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		594	836
Mid Cap Index [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Mid Cap Index [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	594	836
Mid Cap Index [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Small Cap Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		546	714
Small Cap Growth [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Small Cap Growth [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	546	714
Small Cap Growth [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Small Cap Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		588	868
Small Cap Value [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Small Cap Value [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	588	868
Small Cap Value [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Large Cap Blend [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		560	859
Large Cap Blend [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Large Cap Blend [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	560	859
Large Cap Blend [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,843	2,915
Growth [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Growth [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	1,843	2,915
Growth [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
International Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2,251	3,036
International Growth [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
International Growth [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	2,251	3,036
International Growth [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Core Bond [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,658	2,316
Core Bond [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Core Bond [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	1,658	2,316
Core Bond [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
High Yield [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		347	473
High Yield [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
High Yield [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	347	473
High Yield [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Inflation Protected Bond [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		433	641
Inflation Protected Bond [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Inflation Protected Bond [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	433	641
Inflation Protected Bond [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	0	0
Money Market [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		63	35
Money Market [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0	0
Money Market [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[2]	63	35
Money Market [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[3]	$ 0	$ 0

[1] Company common stock is classified as level 1 and valued using quoted prices in active markets for identical assets.

[2] All other plan assets in stock, bond and money market funds are classified as level 2 and valued using significant observable inputs.

[3] There are no plan assets classified as level 3 in the fair value hierarchy as a result of having significant unobservable inputs.