BUSINESS COMBINATION - Narrative (Details) $ / shares in Units, $ in Thousands	Sep. 02, 2025 USD ($) $ / shares
Mechanics Bank Acquisition
Business Combination [Line Items]
Bargain purchase gain \| $	$ 145,460
Legacy Mechanics Bank Shareholders \| Mechanics Bancorp
Business Combination [Line Items]
Economic equity interest after merger	91.70%
Voting equity interest after merger	91.30%
Legacy Homestreet, Inc. Shareholders \| Mechanics Bancorp
Business Combination [Line Items]
Economic equity interest after merger	8.30%
Voting equity interest after merger	8.70%
Common Class A \| Mechanics Bank Acquisition
Business Combination [Line Items]
Business combination, fixed exchange ratio	3,301.092
Common Class A \| Mechanics Bank
Business Combination [Line Items]
Common stock, par value (in dollars per share)	$ 50
Common Class B \| Mechanics Bank Acquisition
Business Combination [Line Items]
Business combination, fixed exchange ratio	330.1092
Common Class B \| Mechanics Bank
Business Combination [Line Items]
Common stock, par value (in dollars per share)	$ 50

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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