Loans and Loans Held for Sale - Restructured Loans for Periods Presented (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Modifications [Line Items]
Restructured loans	$ 6,338	$ 4,777
Performing TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans	23,955	36,983
Performing TDRs | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Restructured loans	6,822	16,939
Performing TDRs | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Restructured loans	6,321	8,074
Performing TDRs | Commercial Construction
Financing Receivable, Modifications [Line Items]
Restructured loans	5,013	5,736
Performing TDRs | Residential Mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans	2,590	2,839
Performing TDRs | Home Equity
Financing Receivable, Modifications [Line Items]
Restructured loans	3,184	3,342
Performing TDRs | Installment and Other Consumer
Financing Receivable, Modifications [Line Items]
Restructured loans	25	53
Nonperforming TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans	7,659	5,436
Nonperforming TDRs | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Restructured loans	3,548	2,180
Nonperforming TDRs | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Restructured loans	1,570	356
Nonperforming TDRs | Commercial Construction
Financing Receivable, Modifications [Line Items]
Restructured loans	1,265	1,869
Nonperforming TDRs | Residential Mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans	665	459
Nonperforming TDRs | Home Equity
Financing Receivable, Modifications [Line Items]
Restructured loans	523	562
Nonperforming TDRs | Installment and Other Consumer
Financing Receivable, Modifications [Line Items]
Restructured loans	88	10
Total TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans	31,614	42,419
Total TDRs | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Restructured loans	10,370	19,119
Total TDRs | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Restructured loans	7,891	8,430
Total TDRs | Commercial Construction
Financing Receivable, Modifications [Line Items]
Restructured loans	6,278	7,605
Total TDRs | Residential Mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans	3,255	3,298
Total TDRs | Home Equity
Financing Receivable, Modifications [Line Items]
Restructured loans	3,707	3,904
Total TDRs | Installment and Other Consumer
Financing Receivable, Modifications [Line Items]
Restructured loans	$ 113	$ 63