Transactions with Parties-in-Interest (Details) - EBP 002 - USD ($)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
EBP, Related Party and Party-in-Interest Transactions [Line Items]
Total investments	$ 144,188,868	$ 128,354,635
Total contributions	12,210,757	11,452,806
Total Additions	30,938,820	$ 27,261,375
EBP, Participant-Directed
EBP, Related Party and Party-in-Interest Transactions [Line Items]
Total contributions	365,166
Total Additions	375,072
Withdrawals, transfers, fees and forfeitures	$ 1,096,487
S&T Bancorp, Inc. common stock
EBP, Related Party and Party-in-Interest Transactions [Line Items]
EBP, Investment, Number of Shares	354,390	361,784
Total investments	$ 13,945,243	$ 13,827,385
Dividends	$ 474,000	$ 487,000

EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan, Transfers, Fees And Forfeitures

No definition available.

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- Definition

Amount of increase in net asset available for benefit to participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

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Amount of increase in net asset available for benefit from contribution to employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

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Amount of increase in net asset available for benefit from interest and dividend income on investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

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- Definition

Fair value of investment, excluding plan interest in master trust, held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, derivative, investment measured at net asset value per share as practical expedient, and insurance contract not meeting fully-benefit responsive investment criteria.

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- Definition

Number of shares or units of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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