v3.26.1
OPERATING SEGMENT INFORMATION (Narrative) (Details)
3 Months Ended
Mar. 31, 2026
branch
segment
state
Segment Reporting Information [Line Items]  
Number of reportable segments | segment 7
Number of branches 407
Number of states in which entity operates | state 11
Utah | Zions Bank  
Segment Reporting Information [Line Items]  
Number of branches 92
Idaho | Zions Bank  
Segment Reporting Information [Line Items]  
Number of branches 25
Wyoming | Zions Bank  
Segment Reporting Information [Line Items]  
Number of branches 1
California | CB&T  
Segment Reporting Information [Line Items]  
Number of branches 77
Texas | Amegy  
Segment Reporting Information [Line Items]  
Number of branches 76
Arizona | NBAZ  
Segment Reporting Information [Line Items]  
Number of branches 56
Nevada | NSB  
Segment Reporting Information [Line Items]  
Number of branches 43
Colorado | Vectra  
Segment Reporting Information [Line Items]  
Number of branches 33
New Mexico | Vectra  
Segment Reporting Information [Line Items]  
Number of branches 1
Washington | TCBW  
Segment Reporting Information [Line Items]  
Number of branches 2
Oregon | TCBW  
Segment Reporting Information [Line Items]  
Number of branches 1