Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	Apr. 30, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	0-12668
Entity Registrant Name	Hills Bancorporation
Entity Incorporation, State or Country Code	IA
Entity Tax Identification Number	42-1208067
Entity Address, Address Line One	131 MAIN STREET
Entity Address, City or Town	HILLS
Entity Address, State or Province	IA
Entity Address, Postal Zip Code	52235
City Area Code	319
Local Phone Number	679-2291
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		9,089,649
Entity Central Index Key	0000732417
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false