LOANS AND LEASES AND ALLOWANCE FOR LOAN AND LEASE LOSSES - Non Traditional Mortgage Loans Additional Information (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 7,700,873,000	$ 6,659,407,000
Percentage decrease in credit score to run exception report	10.00%
Loan Portfolio \| Loan Portfolio Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	100.00%	100.00%
NTM Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 826,731,000	$ 806,933,000
NTM Loans \| Loan Portfolio \| Loan Portfolio Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	10.70%	12.10%
Consumer \| NTM Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 826,731,000	$ 806,933,000
Increase (decrease) in loans receivable	$ 19,800,000
Increase (decrease) in loans receivable, percentage	2.50%
Consumer \| NTM Loans \| Green Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 70,100,000	85,800,000
Interest only notes balloon payment period	15 years
Consumer \| NTM Loans \| Interest Only Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 753,100,000	717,500,000
Consumer \| NTM Loans \| Negative amortization
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	3,500,000	3,700,000
Consumer \| NTM Loans \| Nonperforming Financing Receivable \| Green Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	0	0
Consumer \| NTM Loans \| Nonperforming Financing Receivable \| Interest Only Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	0	1,200,000
Consumer \| NTM Loans \| Nonperforming Financing Receivable \| Negative amortization
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 0	$ 0
Consumer \| NTM Loans \| Loan Portfolio \| Loan Portfolio Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	10.70%	12.10%

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Loans and Leases Receivable, Net Of Deferred Income, Increase (Decrease) in Period

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Mortgage Loans on Real Estate, Periodic Payment Terms, Balloon Payment Period

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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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