Business Combination - Summary of Merger-Related Expenses (Details) - Luther Burbank - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2024	Mar. 31, 2024
Business Acquisition [Line Items]
Merger-related expenses	$ 25,119	$ 25,636
Severance and employee-related
Business Acquisition [Line Items]
Merger-related expenses	20,266	20,266
Legal and Professional
Business Acquisition [Line Items]
Merger-related expenses	3,793	3,982
Charitable contributions
Business Acquisition [Line Items]
Merger-related expenses	1,000	1,000
System conversion and integration
Business Acquisition [Line Items]
Merger-related expenses	$ 60	$ 388

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479405/805-10-25-23

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration