Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 01, 2020	Jun. 28, 2019
Cover [Abstract]
Entity Central Index Key	0001130144
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	000-33063
Entity Registrant Name	SIERRA BANCORP
Entity Incorporation, State or Country Code	CA
Entity Tax Identification Number	33-0937517
Entity Address, Address Line One	86 North Main Street
Entity Address, City or Town	Porterville
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	93257
City Area Code	559
Local Phone Number	782-4900
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 380
Title of 12(b) Security	Common Stock, No Par Value
Trading Symbol	BSRR
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		15,296,888
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Amendment Flag	false