LOANS AND LEASES AND ALLOWANCE FOR LOAN AND LEASE LOSSES - Non Traditional Mortgages Portfolio (Details) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($) Loan	Dec. 31, 2017 USD ($) Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 7,700,873	$ 6,659,407
Loan Portfolio Concentration Risk \| Loan Portfolio
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	$ 806,933
NTM Loans \| Loan Portfolio Concentration Risk \| Loan Portfolio
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]
Count \| Loan	628	592
Total loans and leases (1)	$ 826,731	$ 806,933
Consumer \| NTM Loans \| Loan Portfolio Concentration Risk \| Nontraditional Mortgage Loans Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	100.00%	100.00%
Consumer \| NTM Loans \| Loan Portfolio Concentration Risk \| Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	10.70%	12.10%
Consumer \| NTM Loans \| First lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Count \| Loan	618	580
Total loans and leases (1)	$ 824,318	$ 803,355
Consumer \| NTM Loans \| First lien \| Loan Portfolio Concentration Risk \| Nontraditional Mortgage Loans Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	99.70%	99.60%
Consumer \| NTM Loans \| Second lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Count \| Loan	10	12
Total loans and leases (1)	$ 2,413	$ 3,578
Consumer \| NTM Loans \| Second lien \| Loan Portfolio Concentration Risk \| Nontraditional Mortgage Loans Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	0.30%	0.40%
Consumer \| NTM Loans \| Green Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 70,100	$ 85,800
Consumer \| NTM Loans \| Green Loans \| First lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Count \| Loan	88	101
Total loans and leases (1)	$ 67,729	$ 82,197
Consumer \| NTM Loans \| Green Loans \| First lien \| Loan Portfolio Concentration Risk \| Nontraditional Mortgage Loans Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	8.20%	10.20%
Consumer \| NTM Loans \| Green Loans \| Second lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Count \| Loan	10	12
Total loans and leases (1)	$ 2,413	$ 3,578
Consumer \| NTM Loans \| Green Loans \| Second lien \| Loan Portfolio Concentration Risk \| Nontraditional Mortgage Loans Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	0.30%	0.40%
Consumer \| NTM Loans \| Interest Only Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 753,100	$ 717,500
Consumer \| NTM Loans \| Interest Only Loans \| First lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Count \| Loan	519	468
Total loans and leases (1)	$ 753,061	$ 717,484
Consumer \| NTM Loans \| Interest Only Loans \| First lien \| Loan Portfolio Concentration Risk \| Nontraditional Mortgage Loans Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	91.10%	88.90%
Consumer \| NTM Loans \| Negative amortization
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases (1)	$ 3,500	$ 3,700
Consumer \| NTM Loans \| Negative amortization \| First lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Count \| Loan	11	11
Total loans and leases (1)	$ 3,528	$ 3,674
Consumer \| NTM Loans \| Negative amortization \| First lien \| Loan Portfolio Concentration Risk \| Nontraditional Mortgage Loans Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage to total loans and leases	0.40%	0.50%

Number of mortgage loans within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Footnote 3
-Subsection 29

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Footnote 3))
-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-SubTopic 10
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-SubTopic 10
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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