Cover Page - shares	3 Months Ended
	Mar. 31, 2020	May 11, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-39028
Entity Registrant Name	CROSSFIRST BANKSHARES, INC.
Entity Incorporation, State or Country Code	KS
Entity Tax Identification Number	26-3212879
Entity Address, Address Line One	11440 Tomahawk Creek Parkway
Entity Address, City or Town	Leawood,
Entity Address, State or Province	KS
Entity Address, Postal Zip Code	66211
City Area Code	913
Local Phone Number	312-6822
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	CFB
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		52,113,559
Entity Central Index Key	0001458412
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false