LOANS & ALLOWANCE FOR CREDIT LOSSES-LOANS - UNPAID PRINCIPAL BALANCE FOR PERFORMING AND NONACCRUAL (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	$ 11,554,744	$ 10,703,442
Single Family - Mortgage & Warehouse
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	4,359,472	4,722,304
Multifamily and Commercial Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	2,470,454	2,263,054
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	3,180,453	2,297,920
Commercial & Industrial - Non-RE
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	1,123,869	885,320
Auto & Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	362,180	341,365
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	58,316	193,479
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	11,409,549	10,615,501
Performing | Single Family - Mortgage & Warehouse
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	4,253,764	4,638,274
Performing | Multifamily and Commercial Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	2,450,026	2,259,629
Performing | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	3,164,614	2,297,920
Performing | Commercial & Industrial - Non-RE
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	1,120,927	885,107
Performing | Auto & Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	361,902	341,092
Performing | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	58,316	193,479
Nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	145,195	87,941
Nonaccrual | Single Family - Mortgage & Warehouse
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	105,708	84,030
Nonaccrual | Multifamily and Commercial Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	20,428	3,425
Nonaccrual | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	15,839	0
Nonaccrual | Commercial & Industrial - Non-RE
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	2,942	213
Nonaccrual | Auto & Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	278	273
Nonaccrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	$ 0	$ 0