LOANS & ALLOWANCE FOR CREDIT LOSSES - SCHEDULE OF UNPAID PRINCIPAL BALANCE FOR PERFORMING AND NONACCRUAL (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Jun. 30, 2026
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 26,358,461	$ 26,096,037
Nonaccrual loans to total loans	0.59%	0.60%
Single Family - Mortgage & Warehouse
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 4,446,687	$ 4,581,772
Multifamily and Commercial Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,373,026	2,484,290
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	9,657,946	8,867,851
Commercial & Industrial - Non-RE
Financing Receivable, Credit Quality Indicator [Line Items]
Total	9,160,723	9,495,647
Auto & Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	720,079	666,477
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	26,203,009	25,938,907
Performing \| Single Family - Mortgage & Warehouse
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,386,849	4,523,065
Performing \| Multifamily and Commercial Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,366,745	2,479,258
Performing \| Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	9,642,038	8,853,128
Performing \| Commercial & Industrial - Non-RE
Financing Receivable, Credit Quality Indicator [Line Items]
Total	9,088,766	9,418,504
Performing \| Auto & Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	718,611	664,952
Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total	155,452	157,130
Nonaccrual \| Single Family - Mortgage & Warehouse
Financing Receivable, Credit Quality Indicator [Line Items]
Total	59,838	58,707
Nonaccrual \| Multifamily and Commercial Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,281	5,032
Nonaccrual \| Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	15,908	14,723
Nonaccrual \| Commercial & Industrial - Non-RE
Financing Receivable, Credit Quality Indicator [Line Items]
Total	71,957	77,143
Nonaccrual \| Auto & Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 1,468	$ 1,525