CREDIT QUALITY ASSESSMENT (Information by Credit Risk Rating Indicators for Those Remaining Segments of Loan Portfolio) (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	$ 6,569,990	$ 6,571,634
Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	505,443	517,839
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,249,968	1,228,247
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	176,388	186,785
Homogeneous Loan Pools
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,931,799	1,932,871
Homogeneous Loan Pools | Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	505,443	517,839
Homogeneous Loan Pools | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,249,968	1,228,247
Homogeneous Loan Pools | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	176,388	186,785
Homogeneous Loan Pools | Performing Financing Receivable
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,916,205	1,917,387
Homogeneous Loan Pools | Performing Financing Receivable | Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	501,362	513,513
Homogeneous Loan Pools | Performing Financing Receivable | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,238,611	1,217,248
Homogeneous Loan Pools | Performing Financing Receivable | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	176,232	186,626
Homogeneous Loan Pools | Nonperforming Financing Receivable | Loans 90 Days Or More Past Due
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	221	440
Homogeneous Loan Pools | Nonperforming Financing Receivable | Non Accrual Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	13,941	13,602
Homogeneous Loan Pools | Nonperforming Financing Receivable | Restructured Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,432	1,442
Homogeneous Loan Pools | Nonperforming Financing Receivable | Consumer | Loans 90 Days Or More Past Due
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	219
Homogeneous Loan Pools | Nonperforming Financing Receivable | Consumer | Non Accrual Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	4,081	4,107
Homogeneous Loan Pools | Nonperforming Financing Receivable | Consumer | Restructured Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	0
Homogeneous Loan Pools | Nonperforming Financing Receivable | Residential Real Estate Portfolio Segment | Residential Mortgage | Loans 90 Days Or More Past Due
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	221	221
Homogeneous Loan Pools | Nonperforming Financing Receivable | Residential Real Estate Portfolio Segment | Residential Mortgage | Non Accrual Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	9,704	9,336
Homogeneous Loan Pools | Nonperforming Financing Receivable | Residential Real Estate Portfolio Segment | Residential Mortgage | Restructured Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,432	1,442
Homogeneous Loan Pools | Nonperforming Financing Receivable | Residential Real Estate Portfolio Segment | Residential Construction | Loans 90 Days Or More Past Due
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	0
Homogeneous Loan Pools | Nonperforming Financing Receivable | Residential Real Estate Portfolio Segment | Residential Construction | Non Accrual Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	156	159
Homogeneous Loan Pools | Nonperforming Financing Receivable | Residential Real Estate Portfolio Segment | Residential Construction | Restructured Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	$ 0	$ 0