Credit Quality Assessment (Information by Credit Risk Rating Indicators for Those Remaining Segments of Loan Portfolio) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	$ 3,495,370	$ 3,127,392
Leases
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	54
Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	450,875	425,552
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	796,358	717,886
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	129,281	136,741
Homogeneous Loan Pools
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,376,514	1,280,233
Homogeneous Loan Pools | Leases
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	54
Homogeneous Loan Pools | Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	450,875	425,552
Homogeneous Loan Pools | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	796,358	717,886
Homogeneous Loan Pools | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	129,281	136,741
Homogeneous Loan Pools | Performing Financing Receivable
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,364,504	1,271,784
Homogeneous Loan Pools | Performing Financing Receivable | Leases
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	54
Homogeneous Loan Pools | Performing Financing Receivable | Consumer
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	448,682	423,884
Homogeneous Loan Pools | Performing Financing Receivable | Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	786,959	712,210
Homogeneous Loan Pools | Performing Financing Receivable | Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	128,863	135,636
Homogeneous Loan Pools | Nonperforming Financing Receivable | 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 | Non Accrual Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	11,433	5,785
Homogeneous Loan Pools | Nonperforming Financing Receivable | Restructured Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	577	2,664
Homogeneous Loan Pools | Nonperforming Financing Receivable | Leases | 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 | Leases | Non Accrual Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	0
Homogeneous Loan Pools | Nonperforming Financing Receivable | Leases | Restructured Loans
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	0
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	2,193	1,668
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	0
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	8,822	3,012
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	577	2,664
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	418	1,105
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