CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance at beginning of period at Dec. 31, 2024	$ 1,380,294	$ 103,623	$ 411,785	$ 1,039,035	$ (76,992)	$ (97,157)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	65,301			65,301
Other comprehensive income, net of tax	24,590				24,590
Cash dividends declared	(26,170)			(26,170)
Treasury stock issued for restricted stock awards	(1,536)		(3,908)			2,372
Recognition of restricted stock compensation expense	3,014		3,014
Balance at end of period at Jun. 30, 2025	1,445,493	103,623	410,891	1,078,166	(52,402)	(94,785)
Balance at beginning of period at Mar. 31, 2025	1,418,034	103,623	412,787	1,059,367	(60,635)	(97,108)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31,900			31,900
Other comprehensive income, net of tax	8,233				8,233
Cash dividends declared	(13,101)			(13,101)
Treasury stock issued for restricted stock awards	(1,495)		(3,818)			2,323
Recognition of restricted stock compensation expense	1,922		1,922
Balance at end of period at Jun. 30, 2025	1,445,493	103,623	410,891	1,078,166	(52,402)	(94,785)
Balance at beginning of period at Dec. 31, 2025	1,463,877	103,623	412,969	1,120,297	(41,707)	(131,305)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	71,715			71,715
Other comprehensive income, net of tax	(7,638)				(7,638)
Cash dividends declared	(26,662)			(26,662)
Treasury stock issued for restricted stock awards	(1,734)		(4,400)			2,666
Repurchase of S&T Stock	(98,261)					(98,261)
Recognition of restricted stock compensation expense	2,518		2,518
Balance at end of period at Jun. 30, 2026	1,403,815	103,623	411,087	1,165,350	(49,345)	(226,900)
Balance at beginning of period at Mar. 31, 2026	1,430,681	103,623	413,929	1,141,963	(47,476)	(181,358)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	36,643			36,643
Other comprehensive income, net of tax	(1,869)				(1,869)
Cash dividends declared	(13,256)			(13,256)
Treasury stock issued for restricted stock awards	(1,706)		(4,251)			2,545
Repurchase of S&T Stock	(48,087)					(48,087)
Recognition of restricted stock compensation expense	1,409		1,409
Balance at end of period at Jun. 30, 2026	$ 1,403,815	$ 103,623	$ 411,087	$ 1,165,350	$ (49,345)	$ (226,900)