Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2022	May 04, 2022
Document And Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	000-21344
Document Period End Date	Mar. 31, 2022
Entity Registrant Name	FIRST KEYSTONE CORPORATION
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	23-2249083
Entity Address, Address Line One	111 West Front Street
Entity Address, City or Town	Berwick
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	18603
City Area Code	570
Local Phone Number	752-3671
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Title of 12(b) Security	Common stock
Trading Symbol	FKYS
Entity Common Stock, Shares Outstanding		5,963,521
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Central Index Key	0000737875
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Amendment Flag	false