CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total SMP	Non- Controlling Interest
Beginning balance at Dec. 31, 2024	$ 630,082	$ 47,872	$ 100,135	$ 575,385	$ (25,832)	$ (81,815)	$ 615,745	$ 14,337
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	12,741			12,566			12,566	175
Other comprehensive income (loss), net of tax	12,141				12,177		12,177	(36)
Cash dividends paid	(6,777)			(6,777)			(6,777)
Stock-based compensation	1,550		149			1,401	1,550
Employee Stock Ownership Plan	2,700		(737)			3,437	2,700
Ending balance at Mar. 31, 2025	652,437	47,872	99,547	581,174	(13,655)	(76,977)	637,961	14,476
Beginning balance at Dec. 31, 2025	698,262	47,872	99,005	589,448	17,857	(70,483)	683,699	14,563
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	17,285			17,136			17,136	149
Other comprehensive income (loss), net of tax	(6,029)				(6,193)		(6,193)	164
Cash dividends paid	(7,308)			(7,308)			(7,308)
Dividends to noncontrolling interest	(624)							(624)
Stock-based compensation	2,989		1,742			1,247	2,989
Employee Stock Ownership Plan	3,287		357			2,930	3,287
Purchase of treasury stock	(283)					(283)	(283)
Ending balance at Mar. 31, 2026	$ 707,579	$ 47,872	$ 101,104	$ 599,276	$ 11,664	$ (66,589)	$ 693,327	$ 14,252