Cover - shares	6 Months Ended
	Jun. 30, 2022	Aug. 11, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Entity Registrant Name	CULLMAN BANCORP, INC.
Entity Central Index Key	0001845799
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		7,405,893
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common Stock, per value $0.01 per share
Trading Symbol	CULL
Security Exchange Name	NASDAQ
Entity File Number	001-40607
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	61-1990996
Entity Address, Address Line One	316 Second Avenue
Entity Address, Address Line Two	SW
Entity Address, City or Town	Cullman
Entity Address, State or Province	AL
Entity Address, Postal Zip Code	35055
City Area Code	256
Local Phone Number	734-1740
Document Quarterly Report	true
Document Transition Report	false