Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2024
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans Employee Savings Plan Substantially all of the Company's employees are eligible to participate in the Umpqua Bank 401(k) and Profit Sharing Plan, a defined contribution and profit sharing plan sponsored by the Company. Employees may elect to contribute a portion of their salary to the plan in accordance with Section 401(k) of the Internal Revenue Code. At the discretion of the Board of Directors, the Company may make matching and/or profit sharing contributions based on profits of the Bank. The Company's contributions charged to expense amounted to $13.6 million, $20.9 million, and $10.6 million for the years ended December 31, 2024, 2023, and 2022, respectively. Employee Stock Purchase Plan The Company maintains an ESPP in which substantially all of the Company's employees are eligible to participate. The ESPP provides participants the opportunity to purchase common stock of the Company at a discounted price. Under the ESPP, participants purchase common stock of the Company for 90% of the lowest price on either the first or last day in the look-back period of six months. In 2024, the ESPP had a single offering period from July 1st to December 31st, with no purchases completed during 2024. At December 31, 2024, there were 877,000 shares available for purchase under the ESPP, 78,000 shares were purchased in January 2025 for $1.4 million, following the closing of the July 1st to December 31st 2024 offering period. In 2023, historical Columbia employees participated in the ESPP for the period from January 1st to June 30th of 2023 and purchased 58,000 shares for $1.2 million. Supplemental Retirement/Deferred Compensation Plans The Company has established a Supplemental Retirement & Deferred Compensation Plan (SRP/DCP), a nonqualified deferred compensation plan designed to supplement the retirement income of certain highly compensated executives selected by resolution of the Board. The SRP/DCP has two components: a supplemental retirement plan and a deferred compensation plan. The Company may make discretionary contributions to the SRP. The SRP balances as of December 31, 2024, and 2023 were $536,000 and $517,000, respectively, and are recorded in other liabilities on the Consolidated Balance Sheets. Under the DCP, eligible officers may elect to defer up to 50% of their salary into a plan account. The DCP balance was $14.1 million and $13.1 million as of December 31, 2024, and 2023, respectively. Additionally, the Company has established an SRP for a former CEO. The balance for this plan was $7.8 million and $8.2 million as of December 31, 2024 and 2023, respectively. In connection with the closing of the Merger, the Company established a deferred compensation plan for certain executives. The balances for this plan were $11.6 million and $8.5 million as of December 31, 2024, and 2023, respectively. Supplemental Executive Retirement Plan In connection with the Merger, the Company assumed a SERP, which is unsecured and unfunded with no program assets. The SERP's projected benefit obligation, representing the vested net present value of future payments to individuals under the plan, is accrued over the estimated remaining term of employment of the participants and was determined by actuarial valuation using a discount rate of 5.60% for 2024 and 5.02% for 2023. Additional assumptions and features of the plan include a normal retirement age of 65 and a 2% annual cost of living benefit adjustment. The projected benefit obligation of $18.0 million for 2024 and $18.8 million for 2023 is included in other liabilities on the Consolidated Balance Sheets. Acquired Plans In connection with prior acquisitions, the Bank assumed liability for certain salary continuation, supplemental retirement, and deferred compensation plans for key employees, retired employees, and directors of acquired institutions. No additional contributions have been made to these plans since the effective date of the acquisitions. These unfunded plans provide for the payment of a specified amount on a monthly basis for a specified period (generally 10 to 20 years) after retirement. In the event of a participant employee's death prior to or during retirement, the Bank may be obligated to pay the designated beneficiary the benefits outlined in the plans. As of December 31, 2024 and 2023, liabilities recorded for the estimated present value of future plan benefits totaled $47.2 million and $49.0 million, respectively, and are recorded in other liabilities on the Consolidated Balance Sheets. For the years ended December 31, 2024, 2023, and 2022, expense recorded for these benefits totaled $4.1 million, $4.8 million, and $1.5 million, respectively. Rabbi Trusts The Bank has established irrevocable rabbi trusts for the SRP/DCP plan and sponsors similar trusts for certain deferred compensation plans assumed from prior mergers. The trust assets, generally trading assets, are consolidated in the Company's balance sheets with the associated liabilities, equal to the asset balances, included in other liabilities on the Consolidated Balance Sheets. As of December 31, 2024, and 2023, the asset and liability balances related to these trusts were $15.9 million and $13.7 million, respectively. Bank-Owned Life Insurance The Bank has purchased, or acquired through mergers, life insurance policies in connection with certain executive supplemental income, salary continuation and deferred compensation retirement plans. These policies, for which the Bank is the owner and sole or partial beneficiary, provide protection against the adverse financial effects of a key employee's death and offer tax-exempt income to offset plan expenses. As of December 31, 2024, and 2023, the cash surrender value of these policies was $693.8 million and $680.9 million, respectively. Additionally, as of December 31, 2024, and 2023, the Bank had liabilities for post-retirement benefits payable to other partial beneficiaries under some of these life insurance policies of $6.2 million and $6.3 million, respectively. The Bank is exposed to credit risk if an insurance company cannot fulfill its financial obligations under a policy. To mitigate this risk, the Bank uses a variety of insurance companies and regularly monitors their financial condition.