| Cover | 12 Months Ended |
| Dec. 31, 2022 | |
| Document Information [Line Items] | |
| Document Type | DEF 14A |
| Amendment Flag | false |
| Entity Information [Line Items] | |
| Entity Registrant Name | S&T Bancorp, Inc. |
| Entity Central Index Key | 0000719220 |
| Pay vs Performance Disclosure | 6 Months Ended | 12 Months Ended | 27 Months Ended | ||
| Aug. 31, 2021 | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Mar. 31, 2021 | |
| Pay vs Performance Disclosure [Table] | |||||
| Pay vs Performance [Table Text Block] | PAY VERSUS PERFORMANCE DISCLOSURE In accordance with rules adopted by the Securities mpens Non-PEO Year Summary 1 ($) Summary 1 ($) Summary 1 ($) Compensation 1,2,3 ($) Compensation 1,2,3 ($) Compensation 1,2,3 ($) Average Non-PEO 1 ($) Average Non-PEO 1,2,3 ($) Value of Initial 4 Net Return 5 TSR Peer (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) (k) (l) (m) 2022 — — 2,508,806 — — 2,437,641 941,388 997,835 95.79 110.67 135.5 11.5 % 2021 823,834 1,215,680 887,244 681,430 1,461,391 902,948 621,526 616,621 85.06 132.19 110.3 9.3 % 2020 1,700,525 — — 474,364 — — 961,977 600,989 64.60 92.50 21.0 1.8 % 1. Todd D. Brice was our PEO from January 2019 to March 2021. David G Non-PEO 2020 2021 2022 Mark Kochvar Mark Kochvar Mark Kochvar Ernest J. Draganza George Basara David G. Antolik George Basara Charles B. Carroll, Jr. LaDawn D. Yesho David P. Ruddock LaDawn D. Yesho Stephen A. Drahnak Rebecca A. Stapleton David G. Antolik 2. The amounts shown for Compensation Actually Paid have been calculated in accordance with Item 402(v) of Regulation S-K 3. Compensation Actually Paid reflects the exclusions and inclusions of certain amounts for the PEOs and the Non-PEO th Year Summary Exclusion of Exclusion of Inclusion of Inclusion of Compensation 2021 823,834 — — — (142,404 ) 681,430 2020 1,700,525 (600,500 ) (371,039 ) — (254,622 ) 474,364 Year Summary Exclusion Exclusion of Inclusion of Inclusion of Compensation 2021 1,215,680 — (230,036 ) — 475,747 1,461,391 Year Summary Exclusion of Exclusion of Inclusion of Inclusion of Compensation 2022 2,508,806 — (847,888 ) — 776,723 2,437,641 2021 887,244 — (248,605 ) — 264,309 902,948 Year Average Non-PEO NEOs Average Non-PEO NEOs Average Non-PEO Average Non-PEO Average Non-PEO Average Non-PEO 2022 941,388 — (240,586 ) — 297,032 997,835 2021 621,526 — (141,441 ) — 136,536 616,621 2020 961,977 (152,033 ) (323,765 ) — 114,809 600,989 The amounts in the Inclusion of Equity Values in the tables above a r Year Year-End Change in Vesting- Todd D. Change in Fair Value at Value of Total - 2021 — (179,447 ) — 37,043 — — (142,404 ) 2020 370,440 (491,895 ) — (133,167 ) — — (254,622 ) Year Year-End Change in Vesting- Change in Fair Value at Value of Total - 2021 215,220 137,903 12,195 110,429 — — 475,747 Year Year-End Change in Vesting- Change in Fair Value at Value of Total - 2022 911,843 — — (135,120 ) — — 776,723 2021 264,309 — — — — — 264,309 Year Average Year-End Non-PEO Average Non-PEO Average Non-PEO Average Non-PEO Average Fair for Non-PEO Average Non-PEO Total - Non-PEO 2022 258,734 42,083 — (3,785 ) — — 297,032 2021 137,221 (19,241 ) — 18,556 — — 136,536 2020 352,635 (115,351 ) — (59,319 ) (63,156 ) — 114,809 4. The Peer Group TSR set forth in this table utilizes the NASDAQ Bank Index, which we also utilize in the stock performance graph required by Item 201(e) of Regulation S-K 5. We determined Return on Average Equity to be the most important financial performance measure used to link Company performance to Compensation Actually Paid to our PEOs and Non-PEO me | ||||
| Company Selected Measure Name | Return on Average Equity | ||||
| Named Executive Officers, Footnote [Text Block] | 2020 2021 2022 Mark Kochvar Mark Kochvar Mark Kochvar Ernest J. Draganza George Basara David G. Antolik George Basara Charles B. Carroll, Jr. LaDawn D. Yesho David P. Ruddock LaDawn D. Yesho Stephen A. Drahnak Rebecca A. Stapleton David G. Antolik | ||||
| Peer Group Issuers, Footnote [Text Block] | 4. The Peer Group TSR set forth in this table utilizes the NASDAQ Bank Index, which we also utilize in the stock performance graph required by Item 201(e) of Regulation S-K | ||||
| Adjustment To PEO Compensation, Footnote [Text Block] | Year Summary Exclusion of Exclusion of Inclusion of Inclusion of Compensation 2021 823,834 — — — (142,404 ) 681,430 2020 1,700,525 (600,500 ) (371,039 ) — (254,622 ) 474,364 Year Summary Exclusion Exclusion of Inclusion of Inclusion of Compensation 2021 1,215,680 — (230,036 ) — 475,747 1,461,391 Year Summary Exclusion of Exclusion of Inclusion of Inclusion of Compensation 2022 2,508,806 — (847,888 ) — 776,723 2,437,641 2021 887,244 — (248,605 ) — 264,309 902,948 Year Year-End Change in Vesting- Todd D. Change in Fair Value at Value of Total - 2021 — (179,447 ) — 37,043 — — (142,404 ) 2020 370,440 (491,895 ) — (133,167 ) — — (254,622 ) Year Year-End Change in Vesting- Change in Fair Value at Value of Total - 2021 215,220 137,903 12,195 110,429 — — 475,747 Year Year-End Change in Vesting- Change in Fair Value at Value of Total - 2022 911,843 — — (135,120 ) — — 776,723 2021 264,309 — — — — — 264,309 | ||||
| Non-PEO NEO Average Total Compensation Amount | $ 941,388 | $ 621,526 | $ 961,977 | ||
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 997,835 | 616,621 | 600,989 | ||
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | Year Average Non-PEO NEOs Average Non-PEO NEOs Average Non-PEO Average Non-PEO Average Non-PEO Average Non-PEO 2022 941,388 — (240,586 ) — 297,032 997,835 2021 621,526 — (141,441 ) — 136,536 616,621 2020 961,977 (152,033 ) (323,765 ) — 114,809 600,989 Year Average Year-End Non-PEO Average Non-PEO Average Non-PEO Average Non-PEO Average Fair for Non-PEO Average Non-PEO Total - Non-PEO 2022 258,734 42,083 — (3,785 ) — — 297,032 2021 137,221 (19,241 ) — 18,556 — — 136,536 2020 352,635 (115,351 ) — (59,319 ) (63,156 ) — 114,809 | ||||
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | The following chart sets forth the relationship between Compensation Actually Paid to our PEOs, the average of Compensation Actually Paid to our Non-PEO three m | ||||
| Compensation Actually Paid vs. Net Income [Text Block] | The following chart sets forth the relationship between Compensation Actu ally Paid to our P Non-PEO | ||||
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | The following chart sets forth the relationship between Compensation Actually Paid to our PEO, the average of Compensation Actually Paid to our Non-PEO | ||||
| Total Shareholder Return Vs Peer Group [Text Block] | The following chart compare s our cumu | ||||
| Tabular List [Table Text Block] | Tabular List of Most Important Financial Performance Measures The following table presents the financial performance measures that the Company consi de Return on Average Equity EPS Relative TSR | ||||
| Total Shareholder Return Amount | $ 95.79 | 85.06 | 64.6 | ||
| Peer Group Total Shareholder Return Amount | 110.67 | 132.19 | 92.5 | ||
| Net Income (Loss) | $ 135,500,000 | $ 110,300,000 | $ 21,000,000 | ||
| Company Selected Measure Amount | 0.115 | 0.093 | 0.018 | ||
| Measure [Axis]: 1 | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Measure Name | Return on Average Equity | ||||
| Measure [Axis]: 2 | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Measure Name | EPS | ||||
| Measure [Axis]: 3 | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Measure Name | Relative TSR | ||||
| Todd D. Brice [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| PEO Total Compensation Amount | $ 0 | $ 823,834 | $ 1,700,525 | ||
| PEO Actually Paid Compensation Amount | 0 | 681,430 | 474,364 | ||
| PEO Name | Todd D. Brice | ||||
| David G. Antolik [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| PEO Total Compensation Amount | 0 | 1,215,680 | 0 | ||
| PEO Actually Paid Compensation Amount | 0 | 1,461,391 | 0 | ||
| PEO Name | David G. Antolik | ||||
| Christopher J. McComish [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| PEO Total Compensation Amount | 2,508,806 | 887,244 | 0 | ||
| PEO Actually Paid Compensation Amount | $ 2,437,641 | 902,948 | 0 | ||
| PEO Name | Christopher J. McComish | ||||
| PEO [Member] | Todd D. Brice [Member] | Exclusion of Change in Pension Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | (600,500) | |||
| PEO [Member] | Todd D. Brice [Member] | Exclusion of Stock Awards And Option Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | (371,039) | |||
| PEO [Member] | Todd D. Brice [Member] | Inclusion of Pension Service Cost [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Todd D. Brice [Member] | Inclusion of Equity Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (142,404) | (254,622) | |||
| PEO [Member] | Todd D. Brice [Member] | Year End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 370,440 | |||
| PEO [Member] | Todd D. Brice [Member] | Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (179,447) | (491,895) | |||
| PEO [Member] | Todd D. Brice [Member] | Vesting Date Fair Value of Equity Awards Granted During Year that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Todd D. Brice [Member] | Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 37,043 | (133,167) | |||
| PEO [Member] | Todd D. Brice [Member] | Fair Value at Last Day of Prior Year of Equity Awards Forfeited During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Todd D. Brice [Member] | Value of Dividends or Other Earnings Paid on Equity Awards Not Otherwise Included [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Todd D. Brice [Member] | Total Inclusion of Equity Values [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (142,404) | (254,622) | |||
| PEO [Member] | David G. Antolik [Member] | Exclusion of Change in Pension Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | ||||
| PEO [Member] | David G. Antolik [Member] | Exclusion of Stock Awards And Option Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (230,036) | ||||
| PEO [Member] | David G. Antolik [Member] | Inclusion of Pension Service Cost [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | ||||
| PEO [Member] | David G. Antolik [Member] | Inclusion of Equity Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 475,747 | ||||
| PEO [Member] | David G. Antolik [Member] | Year End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 215,220 | ||||
| PEO [Member] | David G. Antolik [Member] | Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 137,903 | ||||
| PEO [Member] | David G. Antolik [Member] | Vesting Date Fair Value of Equity Awards Granted During Year that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 12,195 | ||||
| PEO [Member] | David G. Antolik [Member] | Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 110,429 | ||||
| PEO [Member] | David G. Antolik [Member] | Fair Value at Last Day of Prior Year of Equity Awards Forfeited During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | ||||
| PEO [Member] | David G. Antolik [Member] | Value of Dividends or Other Earnings Paid on Equity Awards Not Otherwise Included [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | ||||
| PEO [Member] | David G. Antolik [Member] | Total Inclusion of Equity Values [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 475,747 | ||||
| PEO [Member] | Christopher J. McComish [Member] | Exclusion of Change in Pension Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | $ 0 | 0 | |||
| PEO [Member] | Christopher J. McComish [Member] | Exclusion of Stock Awards And Option Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (847,888) | (248,605) | |||
| PEO [Member] | Christopher J. McComish [Member] | Inclusion of Pension Service Cost [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Christopher J. McComish [Member] | Inclusion of Equity Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 776,723 | 264,309 | |||
| PEO [Member] | Christopher J. McComish [Member] | Year End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 911,843 | 264,309 | |||
| PEO [Member] | Christopher J. McComish [Member] | Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Christopher J. McComish [Member] | Vesting Date Fair Value of Equity Awards Granted During Year that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Christopher J. McComish [Member] | Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (135,120) | 0 | |||
| PEO [Member] | Christopher J. McComish [Member] | Fair Value at Last Day of Prior Year of Equity Awards Forfeited During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Christopher J. McComish [Member] | Value of Dividends or Other Earnings Paid on Equity Awards Not Otherwise Included [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | |||
| PEO [Member] | Christopher J. McComish [Member] | Total Inclusion of Equity Values [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 776,723 | 264,309 | |||
| Non-PEO NEO [Member] | Exclusion of Change in Pension Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | (152,033) | ||
| Non-PEO NEO [Member] | Exclusion of Stock Awards And Option Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (240,586) | (141,441) | (323,765) | ||
| Non-PEO NEO [Member] | Inclusion of Pension Service Cost [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | 0 | ||
| Non-PEO NEO [Member] | Inclusion of Equity Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 297,032 | 136,536 | 114,809 | ||
| Non-PEO NEO [Member] | Year End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 258,734 | 137,221 | 352,635 | ||
| Non-PEO NEO [Member] | Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 42,083 | (19,241) | (115,351) | ||
| Non-PEO NEO [Member] | Vesting Date Fair Value of Equity Awards Granted During Year that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | 0 | ||
| Non-PEO NEO [Member] | Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (3,785) | 18,556 | (59,319) | ||
| Non-PEO NEO [Member] | Fair Value at Last Day of Prior Year of Equity Awards Forfeited During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | (63,156) | ||
| Non-PEO NEO [Member] | Value of Dividends or Other Earnings Paid on Equity Awards Not Otherwise Included [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 0 | 0 | ||
| Non-PEO NEO [Member] | Total Inclusion of Equity Values [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | $ 297,032 | $ 136,536 | $ 114,809 | ||
