LOANS AND ALLOWANCE FOR LOAN LOSSES - Non Traditional Mortgage Performance by Credit Score (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 5,951,885	$ 7,700,873
NTM Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 600,656	$ 826,731
Consumer \| NTM Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Count \| loan	461	628
Total loans	$ 600,656	$ 826,731
Increase (decrease) in loans receivable	$ (226,100)
Increase (decrease) in loans receivable (percent)	(27.30%)
Consumer \| NTM Loans \| First lien
Financing Receivable, Credit Quality Indicator [Line Items]
Count \| loan	454	618
Total loans	$ 598,357	$ 824,318
Consumer \| NTM Loans \| Green Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 52,300	$ 70,100
Consumer \| NTM Loans \| Green Loans \| First lien
Financing Receivable, Credit Quality Indicator [Line Items]
Count \| loan	69	88
Total loans	$ 49,959	$ 67,729
Increase (decrease) in count of loans receivable \| loan	(19)
Increase (decrease) in loans receivable	$ (17,770)
Consumer \| NTM Loans \| Green Loans \| First lien \| Loan Portfolio Concentration Risk \| Non-Traditional Single Family Residential Mortgage Green Loans First Lien Portfolio
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage to total loans and leases (percent)	100.00%	100.00%
Increase (decrease) in loans receivable (percent)	(26.20%)
Consumer \| NTM Loans \| Green Loans \| First lien \| Greater than 800
Financing Receivable, Credit Quality Indicator [Line Items]
Count \| loan	13	16
Total loans	$ 3,509	$ 10,617
Increase (decrease) in count of loans receivable \| loan	(3)
Increase (decrease) in loans receivable	$ (7,108)
Consumer \| NTM Loans \| Green Loans \| First lien \| Greater than 800 \| Loan Portfolio Concentration Risk \| Non-Traditional Single Family Residential Mortgage Green Loans First Lien Portfolio
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage to total loans and leases (percent)	7.00%	15.70%
Increase (decrease) in loans receivable (percent)	(66.90%)
Consumer \| NTM Loans \| Green Loans \| First lien \| 700-799
Financing Receivable, Credit Quality Indicator [Line Items]
Count \| loan	38	50
Total loans	$ 27,011	$ 34,888
Increase (decrease) in count of loans receivable \| loan	(12)
Increase (decrease) in loans receivable	$ (7,877)
Consumer \| NTM Loans \| Green Loans \| First lien \| 700-799 \| Loan Portfolio Concentration Risk \| Non-Traditional Single Family Residential Mortgage Green Loans First Lien Portfolio
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage to total loans and leases (percent)	54.10%	51.50%
Increase (decrease) in loans receivable (percent)	(22.60%)
Consumer \| NTM Loans \| Green Loans \| First lien \| 600-699
Financing Receivable, Credit Quality Indicator [Line Items]
Count \| loan	10	16
Total loans	$ 12,400	$ 14,098
Increase (decrease) in count of loans receivable \| loan	(6)
Increase (decrease) in loans receivable	$ (1,698)
Consumer \| NTM Loans \| Green Loans \| First lien \| 600-699 \| Loan Portfolio Concentration Risk \| Non-Traditional Single Family Residential Mortgage Green Loans First Lien Portfolio
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage to total loans and leases (percent)	24.80%	20.80%
Increase (decrease) in loans receivable (percent)	(12.00%)
Consumer \| NTM Loans \| Green Loans \| First lien \| Less than 600
Financing Receivable, Credit Quality Indicator [Line Items]
Count \| loan	5	3
Total loans	$ 3,286	$ 4,347
Increase (decrease) in count of loans receivable \| loan	2
Increase (decrease) in loans receivable	$ (1,061)
Consumer \| NTM Loans \| Green Loans \| First lien \| Less than 600 \| Loan Portfolio Concentration Risk \| Non-Traditional Single Family Residential Mortgage Green Loans First Lien Portfolio
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage to total loans and leases (percent)	6.60%	6.40%
Increase (decrease) in loans receivable (percent)	(24.40%)
Consumer \| NTM Loans \| Green Loans \| First lien \| No FICO score
Financing Receivable, Credit Quality Indicator [Line Items]
Count \| loan	3	3
Total loans	$ 3,753	$ 3,779
Increase (decrease) in count of loans receivable \| loan	0
Increase (decrease) in loans receivable	$ (26)
Consumer \| NTM Loans \| Green Loans \| First lien \| No FICO score \| Loan Portfolio Concentration Risk \| Non-Traditional Single Family Residential Mortgage Green Loans First Lien Portfolio
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage to total loans and leases (percent)	7.50%	5.60%
Increase (decrease) in loans receivable (percent)	(0.70%)

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Loans and Leases Receivable, Increase (Decrease) in Number of Loans

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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