Note 9 - Fair Value of Assets and Liabilities - Fair Value Measurements, Recorded (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Total assets at fair value	$ 20,190	$ 16,896
Total liabilities recorded at fair value	5,920	5,224
Supplemental Executive Retirement Plan [Member]
Derivative asset	14,814	11,617
Metal Swaps [Member]
Derivative asset	5,376	4,458
Metal swaps	5,308	5,224
Embedded Customer Derivatives [Member]
Derivative asset		766
Metal swaps	68
Interest Rate Swap [Member]
Derivative asset		55
Forward Interest Rate Hedge [Member]
Metal swaps	544
Fair Value, Inputs, Level 1 [Member]
Total assets at fair value	14,814	11,617
Total liabilities recorded at fair value	0	0
Fair Value, Inputs, Level 1 [Member] \| Supplemental Executive Retirement Plan [Member]
Derivative asset	14,814	11,617
Fair Value, Inputs, Level 1 [Member] \| Metal Swaps [Member]
Derivative asset	0	0
Metal swaps	0	0
Fair Value, Inputs, Level 1 [Member] \| Embedded Customer Derivatives [Member]
Derivative asset		0
Metal swaps	0
Fair Value, Inputs, Level 1 [Member] \| Interest Rate Swap [Member]
Derivative asset		0
Fair Value, Inputs, Level 1 [Member] \| Forward Interest Rate Hedge [Member]
Metal swaps	0
Fair Value, Inputs, Level 2 [Member]
Total assets at fair value	5,376	5,279
Total liabilities recorded at fair value	5,920	5,224
Fair Value, Inputs, Level 2 [Member] \| Supplemental Executive Retirement Plan [Member]
Derivative asset	0	0
Fair Value, Inputs, Level 2 [Member] \| Metal Swaps [Member]
Derivative asset	5,376	4,458
Metal swaps	5,308	5,224
Fair Value, Inputs, Level 2 [Member] \| Embedded Customer Derivatives [Member]
Derivative asset		766
Metal swaps	68
Fair Value, Inputs, Level 2 [Member] \| Interest Rate Swap [Member]
Derivative asset		55
Fair Value, Inputs, Level 2 [Member] \| Forward Interest Rate Hedge [Member]
Metal swaps	544
Fair Value, Inputs, Level 3 [Member]
Total assets at fair value	0	0
Total liabilities recorded at fair value	0	0
Fair Value, Inputs, Level 3 [Member] \| Supplemental Executive Retirement Plan [Member]
Derivative asset	0	0
Fair Value, Inputs, Level 3 [Member] \| Metal Swaps [Member]
Derivative asset	0	0
Metal swaps	0	0
Fair Value, Inputs, Level 3 [Member] \| Embedded Customer Derivatives [Member]
Derivative asset		0
Metal swaps	0
Fair Value, Inputs, Level 3 [Member] \| Interest Rate Swap [Member]
Derivative asset		$ 0
Fair Value, Inputs, Level 3 [Member] \| Forward Interest Rate Hedge [Member]
Metal swaps	$ 0