FAIR VALUE MEASUREMENTS - FV of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025
Assets:
Securities held-to-maturity	$ 1,149,969	$ 1,170,818
Mortgage servicing rights – multifamily and SBA	57,630	58,095	$ 0
Estimate of Fair Value Measurement
Assets:
Cash and cash equivalents	483,513	1,029,983
Securities held-to-maturity	1,149,969	1,170,818
Loan receivables, net	13,193,078	13,665,520
Liabilities:
Time deposits	2,132,552	2,768,873
Long-term debt	140,594	203,272
Carrying Value
Assets:
Cash and cash equivalents	483,513	1,029,983
Securities held-to-maturity	1,313,520	1,336,632
Loan receivables, net	13,695,413	14,023,617
Liabilities:
Time deposits	2,144,670	2,784,608
Long-term debt	128,815	192,014
Multifamily \| Estimate of Fair Value Measurement
Assets:
Mortgage servicing rights – multifamily and SBA	27,282	28,276
Multifamily \| Carrying Value
Assets:
Mortgage servicing rights – multifamily and SBA	26,370	27,737
Level 1 \| Estimate of Fair Value Measurement
Assets:
Cash and cash equivalents	483,513	1,029,983
Securities held-to-maturity	0	0
Loan receivables, net	0	0
Liabilities:
Time deposits	0	0
Long-term debt	0	0
Level 1 \| Multifamily \| Estimate of Fair Value Measurement
Assets:
Mortgage servicing rights – multifamily and SBA	0	0
Level 2 \| Estimate of Fair Value Measurement
Assets:
Cash and cash equivalents	0	0
Securities held-to-maturity	1,146,969	1,167,818
Loan receivables, net		0
Liabilities:
Time deposits	2,132,552	2,768,873
Long-term debt	140,594	203,272
Level 2 \| Multifamily \| Estimate of Fair Value Measurement
Assets:
Mortgage servicing rights – multifamily and SBA	27,282	28,276
Level 3 \| Estimate of Fair Value Measurement
Assets:
Cash and cash equivalents	0	0
Securities held-to-maturity	3,000	3,000
Loan receivables, net	13,193,078	13,665,520
Liabilities:
Time deposits	0	0
Long-term debt	0	0
Level 3 \| Multifamily \| Estimate of Fair Value Measurement
Assets:
Mortgage servicing rights – multifamily and SBA	$ 0	$ 0

Loan And Lease Receivables, Fair Value Disclosure

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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