Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 23, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	0-12508
Entity Registrant Name	S&T BANCORP, INC.
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	25-1434426
Entity Address, Address Line One	800 Philadelphia Street
Entity Address, City or Town	Indiana
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	15701
City Area Code	800
Local Phone Number	325-2265
Title of 12(b) Security	Common Stock, par value $2.50 per share
Trading Symbol	STBA
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,058,883,499
Entity Common Stock, Shares Outstanding		38,998,241
Documents Incorporated by Reference	Portions of the definitive Proxy Statement of S&T Bancorp, Inc., to be filed pursuant to Regulation 14A for the 2023 annual meeting of shareholders are incorporated by reference into Part III of this Annual Report on Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Central Index Key	0000719220