v3.22.4
Document and Entity Information - USD ($)
$ / shares in Units, $ in Billions
 12 Months Ended
Dec. 31, 2022
Jan. 25, 2023
Jun. 30, 2022
Dec. 31, 2021
Entity Information [Line Items]        
Document Type 10-K      
Document Annual Report true      
Document Period End Date Dec. 31, 2022      
Current Fiscal Year End Date --12-31      
Document Fiscal Year Focus 2022      
Document Transition Report false      
Entity File Number 001-13221      
Entity Registrant Name CULLEN/FROST BANKERS, INC.      
Entity Incorporation, State or Country Code TX      
Entity Tax Identification Number 74-1751768      
Entity Address, Address Line One 111 W. Houston Street,      
Entity Address, City or Town San Antonio,      
Entity Address, State or Province TX      
Entity Address, Postal Zip Code 78205      
City Area Code (210)      
Local Phone Number 220-4011      
Entity Well-known Seasoned Issuer Yes      
Entity Voluntary Filers No      
Entity Current Reporting Status Yes      
Entity Interactive Data Current Yes      
Entity Filer Category Large Accelerated Filer      
Entity Small Business false      
Entity Emerging Growth Company false      
ICFR Auditor Attestation Flag true      
Entity Shell Company false      
Entity Public Float     $ 7.2  
Entity Common Stock, Shares Outstanding   64,360,313    
Common Stock, Par or Stated Value Per Share $ 0.01     $ 0.01
Entity Central Index Key 0000039263      
Amendment Flag false      
Document Fiscal Period Focus FY      
Auditor Name Ernst & Young LLP      
Auditor Location San Antonio, Texas      
Auditor Firm ID 42      
Common Stock [Member] | NEW YORK STOCK EXCHANGE, INC. [Member]        
Entity Information [Line Items]        
Title of 12(b) Security Common Stock, $.01 Par Value      
Trading Symbol CFR      
Security Exchange Name NYSE      
Series B Preferred Stock [Member] | NEW YORK STOCK EXCHANGE, INC. [Member]        
Entity Information [Line Items]        
Title of 12(b) Security Depositary Shares, each representing a 1/40th interest in a share of 4.450% Non-Cumulative Perpetual Preferred Stock, Series B      
Trading Symbol CFR.PrB      
Security Exchange Name NYSE