v3.26.1
Schedule H, Line 4i – Schedule of Assets (Held At End of Year) (Details) - EBP 001
$ in Thousands
12 Months Ended
Dec. 31, 2025
USD ($)
EBP, Schedule of Asset Held for Investment [Line Items]  
Entity tax identification number 91-1422237
Plan number 001
Cost $ 0
Participant Loan 12,219
Asset held for investment 848,872
Collective trusts  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 439,096
Registered investment companies  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 379,666
Money markets and other cash equivalents  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 176
Common stock – Columbia Banking System, Inc.  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 15,070
Self-directed brokerage accounts  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value $ 2,645
Minimum  
EBP, Schedule of Asset Held for Investment [Line Items]  
Participant loan interest rate 3.25%
Maximum  
EBP, Schedule of Asset Held for Investment [Line Items]  
Participant loan interest rate 9.50%
Investment, Identifier [Axis]: BlackRock High Yield Bond Portfolio Class K | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value $ 7,265
Investment, Identifier [Axis]: Cohen & Steers U.S. Realty Fund Class RS | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 5,284
Investment, Identifier [Axis]: Dodge & Cox Income Fund Class X | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 15,567
Investment, Identifier [Axis]: Dodge & Cox International Stock Fund Class X | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 13,006
Investment, Identifier [Axis]: Fidelity 500 Index Fund | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 95,122
Investment, Identifier [Axis]: Fidelity Blue Chip Growth Fund Class K6 | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 64,208
Investment, Identifier [Axis]: Fidelity Inflation-Protected Bond Index Fund | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 5,810
Investment, Identifier [Axis]: Fidelity Mid Cap Index Fund | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 12,951
Investment, Identifier [Axis]: Fidelity Small Cap Index Fund | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 26,225
Investment, Identifier [Axis]: Fidelity Total International Index Fund | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 17,826
Investment, Identifier [Axis]: Fidelity U.S. Bond Index Fund | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 7,456
Investment, Identifier [Axis]: John Hancock Small Cap Core Fund Class R6 | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 3,583
Investment, Identifier [Axis]: Putnam Stable Value Fund 15 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 29,419
Investment, Identifier [Axis]: T. Rowe Price Capital Appreciation Fund I Class | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 13,635
Investment, Identifier [Axis]: T. Rowe Price Diversified Mid-Cap Growth Fund I Class | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 29,011
Investment, Identifier [Axis]: Vanguard International Growth Fund Admiral Shares | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 6,312
Investment, Identifier [Axis]: Vanguard Mid-Cap Value Index Fund Admiral Shares | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 30,181
Investment, Identifier [Axis]: Vanguard Target 2020 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 19,158
Investment, Identifier [Axis]: Vanguard Target 2025 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 42,978
Investment, Identifier [Axis]: Vanguard Target 2030 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 62,053
Investment, Identifier [Axis]: Vanguard Target 2035 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 54,889
Investment, Identifier [Axis]: Vanguard Target 2040 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 64,582
Investment, Identifier [Axis]: Vanguard Target 2045 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 62,899
Investment, Identifier [Axis]: Vanguard Target 2050 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 43,415
Investment, Identifier [Axis]: Vanguard Target 2055 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 31,753
Investment, Identifier [Axis]: Vanguard Target 2060 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 8,335
Investment, Identifier [Axis]: Vanguard Target 2065 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 4,469
Investment, Identifier [Axis]: Vanguard Target 2070 | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 831
Investment, Identifier [Axis]: Vanguard Target Inc | Collective trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value 9,031
Investment, Identifier [Axis]: Vanguard Value Index Fund Institutional Shares | Registered investment company  
EBP, Schedule of Asset Held for Investment [Line Items]  
Current Value $ 31,508