LOANS AND LEASES - Commercial and Consumer Credit Exposure by Risk Attribute (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Commercial	$ 2,426,590	$ 1,912,743
Real Estate - Construction	565,077	467,730
Real Estate - Commercial	3,868,143	2,490,091
Lease financing	95,317	89,347
Total Commercial	6,955,127	4,959,911
Pass
Financing Receivable, Recorded Investment [Line Items]
Commercial	2,335,925	1,882,464
Real Estate - Construction	552,973	467,687
Real Estate - Commercial	3,757,627	2,446,999
Lease financing	92,551	88,078
Total Commercial	6,739,076	4,885,228
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Commercial	39,060	6,226
Real Estate - Construction	12,094	0
Real Estate - Commercial	49,463	4,436
Lease financing	0	0
Total Commercial	100,617	10,662
Substandard
Financing Receivable, Recorded Investment [Line Items]
Commercial	51,605	24,053
Real Estate - Construction	10	43
Real Estate - Commercial	61,053	38,656
Lease financing	2,766	1,269
Total Commercial	115,434	64,021
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Commercial	0	0
Real Estate - Construction	0	0
Real Estate - Commercial	0	0
Lease financing	0	0
Total Commercial	0	0
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	932,962	471,391
Residential real estate \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	919,440	463,459
Residential real estate \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	13,522	7,932
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	816,133	493,604
Home equity \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	809,653	489,148
Home equity \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	6,480	4,456
Installment
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	97,413	41,586
Installment \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	97,097	41,331
Installment \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	316	255
Credit card
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	45,741	46,691
Credit card \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	45,741	46,691
Credit card \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	0	0
Total consumer loans
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	1,892,249	1,053,272
Total consumer loans \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	1,871,931	1,040,629
Total consumer loans \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	$ 20,318	$ 12,643

Loans and Leases Receivable, Gross, Total of Commercial, Consumer Real Estate/Construction and Commercial Mortgage

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Amount before allowance of commercial leases and leveraged lease transactions where the entity is long-term creditor. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes leases covered under loss sharing agreements.

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Amount, before allowance and fees, of loans and leases receivable. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of loans issued to commercial and industrial institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes real estate loans and loans covered under loss sharing agreements.

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Amount before allowance of commercial construction loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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