v3.22.4
Borrowed Funds (Narrative) (Detail)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 17, 2017
USD ($)
Dec. 31, 2021
USD ($)
Dec. 31, 2022
USD ($)
quarter
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2004
USD ($)
Borrowed Funds [Line Items]            
Federal funds purchased   $ 25,925 $ 51,650 $ 25,925    
Repurchase agreements   2,740,799 4,660,641 2,740,799    
Subordinated notes   99,178 99,335 99,178    
Junior subordinated deferrable interest debentures   123,011 123,069 123,011    
Principal payments on long-term borrowings     $ 0 13,403 $ 0  
Proceeds from issuance of Common Equity Securities         $ 145,452  
Maximum number of quarterly periods by which the corporation has the right to defer interest payments on junior subordinated deferrable interest debentures | quarter     20      
Cullen Frost Capital Trust II [Member]            
Borrowed Funds [Line Items]            
Maturity date           Mar. 01, 2034
Proceeds from Issuance of Trust Preferred Securities           $ 120,000
Floating rate 3 month Libor plus margin           1.55%
Proceeds from issuance of Common Equity Securities           $ 3,700
Federal Funds Purchased [Member] | Minimum [Member]            
Borrowed Funds [Line Items]            
Short term debt maturity period     1 day      
Federal Funds Purchased [Member] | Maximum [Member]            
Borrowed Funds [Line Items]            
Short term debt maturity period     90 days      
Securities Loaned or Sold under Agreements to Repurchase [Member] | Minimum [Member]            
Borrowed Funds [Line Items]            
Short term debt maturity period     30 days      
Securities Loaned or Sold under Agreements to Repurchase [Member] | Maximum [Member]            
Borrowed Funds [Line Items]            
Short term debt maturity period     90 days      
Subordinated Debt [Member]            
Borrowed Funds [Line Items]            
Subordinated notes $ 100,000          
Subordinated notes interest rate 4.50%          
Maturity date Mar. 17, 2027          
Unamortized debt issuance cost related to note   822 $ 665 822    
Junior Subordinated Deferrable Interest Debenture [Member] | Cullen Frost Capital Trust II [Member]            
Borrowed Funds [Line Items]            
Unamortized debt issuance cost related to note   701 643 701    
Junior subordinated deferrable interest debentures   123,700 $ 123,700 $ 123,700   $ 123,700
Floating rate 3 month Libor plus margin     6.31% 1.72%    
Junior Subordinated Deferrable Interest Debenture [Member] | WNB Capital Trust I [Member]            
Borrowed Funds [Line Items]            
Principal payments on long-term borrowings   $ 13,400