Parent Company Condensed Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
OPERATING ACTIVITIES
Net income	$ 131,265	$ 144,781	$ 135,520
Net Cash Provided by Operating Activities	173,367	171,749	240,525
FINANCING ACTIVITIES
Repayments on long-term borrowings	(38,381)	(5,464)	(7,689)
Repurchase of shares for taxes on restricted stock	(870)	(798)	(808)
Repurchase of common stock	0	(19,808)	(7,637)
Cash dividends paid to common shareholders	(50,974)	(49,708)	(46,952)
Net Cash (Used in) Provided by Financing Activities	(43,867)	296,073	(554,053)
Net increase (decrease) in cash and due from banks	11,208	23,603	(712,206)
Cash and due from banks at beginning of period	233,612	210,009	922,215
Cash and Due From Banks at End of Period	244,820	233,612	210,009
S&T
OPERATING ACTIVITIES
Net income	131,265	144,781	135,520
Equity in undistributed (earnings) losses of subsidiaries	(70,334)	(63,489)	(78,543)
Other	9,484	1,402	1,468
Net Cash Provided by Operating Activities	70,415	82,694	58,445
FINANCING ACTIVITIES
Repayments on long-term borrowings	0	(5,464)	0
Repurchase of shares for taxes on restricted stock	(870)	(798)	(808)
Repurchase of common stock	0	(19,808)	(7,637)
Cash dividends paid to common shareholders	(50,974)	(49,708)	(46,952)
Net Cash (Used in) Provided by Financing Activities	(51,844)	(75,778)	(55,397)
Net increase (decrease) in cash and due from banks	18,571	6,916	3,048
Cash and due from banks at beginning of period	20,733	13,817	10,769
Cash and Due From Banks at End of Period	$ 39,304	$ 20,733	$ 13,817