FAIR VALUES OF FINANCIAL INSTRUMENTS - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financial assets
Cash and cash equivalents	$ 373,472	$ 391,592
Securities available-for-sale	912,580	1,992,500
Federal Home Loan Bank and other bank stock	59,420	68,094
Loans held-for-sale	22,642	27,606
Loans receivable, net of allowance	5,894,732	7,513,910
Accrued interest receivable	24,523	38,807
Derivative assets	3,583	1,534
Financial liabilities
Deposits	5,430,536	7,689,324
Advances from Federal Home Loan Bank	1,222,709	1,517,761
Long-term debt	180,213	174,059
Derivative liabilities	3,853	1,600
Accrued interest payable	4,687	13,253
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets
Cash and cash equivalents	373,472	391,592
Securities available-for-sale	0	0
Federal Home Loan Bank and other bank stock	0	0
Loans held-for-sale	0	0
Loans receivable, net of allowance	0	0
Accrued interest receivable	24,523	38,807
Derivative assets	0	0
Financial liabilities
Deposits	0	0
Advances from Federal Home Loan Bank	0	0
Long-term debt	0	0
Derivative liabilities	0	0
Accrued interest payable	4,687	13,253
Significant Other Observable Inputs (Level 2)
Financial assets
Cash and cash equivalents	0	0
Securities available-for-sale	912,580	1,992,500
Federal Home Loan Bank and other bank stock	59,420	68,094
Loans held-for-sale	3,409	2,566
Loans receivable, net of allowance	0	0
Accrued interest receivable	0	0
Derivative assets	3,583	1,534
Financial liabilities
Deposits	0	0
Advances from Federal Home Loan Bank	1,222,709	1,517,761
Long-term debt	180,213	174,059
Derivative liabilities	3,853	1,600
Accrued interest payable	0	0
Significant Unobservable Inputs (Level 3)
Financial assets
Cash and cash equivalents	0	0
Securities available-for-sale	0	0
Federal Home Loan Bank and other bank stock	0	0
Loans held-for-sale	19,233	25,040
Loans receivable, net of allowance	5,894,732	7,513,910
Accrued interest receivable	0	0
Derivative assets	0	0
Financial liabilities
Deposits	5,430,536	7,689,324
Advances from Federal Home Loan Bank	0	0
Long-term debt	0	0
Derivative liabilities	0	0
Accrued interest payable	0	0
Carrying Value
Financial assets
Cash and cash equivalents	373,472	391,592
Securities available-for-sale	912,580	1,992,500
Federal Home Loan Bank and other bank stock	59,420	68,094
Loans held-for-sale	22,642	27,606
Loans receivable, net of allowance	5,894,236	7,638,681
Accrued interest receivable	24,523	38,807
Derivative assets	3,583	1,534
Financial liabilities
Deposits	5,427,167	7,916,644
Advances from Federal Home Loan Bank	1,195,000	1,520,000
Long-term debt	173,421	173,174
Derivative liabilities	3,853	1,600
Accrued interest payable	4,687	13,253
Banc home loans \| Disposals
Financial liabilities
Loans held-for-sale, carried at fair value	$ 0	19,490
Nonrecurring \| Banc home loans \| Disposals
Financial liabilities
Loans held-for-sale, carried at fair value		19,500
Nonrecurring \| Banc home loans \| Disposals \| Significant Other Observable Inputs (Level 2)
Financial liabilities
Loans held-for-sale, carried at fair value		2,100
Nonrecurring \| Banc home loans \| Disposals \| Significant Unobservable Inputs (Level 3)
Financial liabilities
Loans held-for-sale, carried at fair value		$ 17,400

Disposal Group, Including Discontinued Operation, Loans Receivable Held-For-Sale, Net

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Investment in Federal Home Loan and Other Banks Stock, Fair Value Disclosure

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Fair value portion of amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties.

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Fair value portion of accrued expenses.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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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 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 portion of borrowing from Federal Home Loan Bank (FHLBank).

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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