CREDIT QUALITY ASSESSMENT (Information by Credit Risk Rating Indicators for Those Remaining Segments of Loan Portfolio) (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	$ 6,250,073	$ 4,314,248
Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	525,574	455,829
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,106,674	921,435
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	197,372	176,687
Homogeneous Loan Pools
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,829,620	1,553,951
Homogeneous Loan Pools | Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	525,574	455,829
Homogeneous Loan Pools | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,106,674	921,435
Homogeneous Loan Pools | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	197,372	176,687
Homogeneous Loan Pools | Performing Financing Receivable
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,818,025	1,542,496
Homogeneous Loan Pools | Performing Financing Receivable | Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	521,276	452,862
Homogeneous Loan Pools | Performing Financing Receivable | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,099,545	913,124
Homogeneous Loan Pools | Performing Financing Receivable | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	197,204	176,510
Homogeneous Loan Pools | Nonperforming Financing Receivable | Loans 90 Days Or More Past Due
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	225
Homogeneous Loan Pools | Nonperforming Financing Receivable | Non Accrual Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	10,717	10,340
Homogeneous Loan Pools | Nonperforming Financing Receivable | Restructured Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	878	890
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	0
Homogeneous Loan Pools | Nonperforming Financing Receivable | Consumer | Non Accrual Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	4,298	2,967
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	0	225
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	6,251	7,196
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	878	890
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	168	177
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