Loans and Loans Held for Sale - Restructured Loans for Periods Stated (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) contract	Mar. 31, 2015 USD ($) contract
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	16	20
Pre-Modification Outstanding Recorded Investment	$ 2,646	$ 4,612
Post-Modification Outstanding Recorded Investment	2,614	4,585
Total Difference in Recorded Investment	$ (32)	$ (27)
Principal deferral
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	9
Pre-Modification Outstanding Recorded Investment		$ 3,616
Post-Modification Outstanding Recorded Investment	$ 0	3,615
Total Difference in Recorded Investment	$ 0	$ (1)
Principal deferral | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	2
Pre-Modification Outstanding Recorded Investment	$ 0	$ 2,851
Post-Modification Outstanding Recorded Investment	0	2,851
Total Difference in Recorded Investment	$ 0	$ 0
Principal deferral | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	6
Pre-Modification Outstanding Recorded Investment	$ 0	$ 661
Post-Modification Outstanding Recorded Investment	0	661
Total Difference in Recorded Investment	$ 0	$ 0
Principal deferral | Commercial Construction
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	1
Pre-Modification Outstanding Recorded Investment	$ 0	$ 104
Post-Modification Outstanding Recorded Investment	0	103
Total Difference in Recorded Investment	$ 0	$ (1)
Principal deferral | Home Equity
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	0	0
Total Difference in Recorded Investment	$ 0	$ 0
Chapter 7 Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	9	9
Pre-Modification Outstanding Recorded Investment	$ 1,175	$ 145
Post-Modification Outstanding Recorded Investment	1,164	134
Total Difference in Recorded Investment	$ (11)	$ (11)
Chapter 7 Bankruptcy | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	0
Pre-Modification Outstanding Recorded Investment	$ 709	$ 0
Post-Modification Outstanding Recorded Investment	702	0
Total Difference in Recorded Investment	$ (7)	$ 0
Chapter 7 Bankruptcy | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	0	1
Pre-Modification Outstanding Recorded Investment	$ 0	$ 3
Post-Modification Outstanding Recorded Investment	0	1
Total Difference in Recorded Investment	$ 0	$ (2)
Chapter 7 Bankruptcy | Residential Mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	3	0
Pre-Modification Outstanding Recorded Investment	$ 221	$ 0
Post-Modification Outstanding Recorded Investment	219	0
Total Difference in Recorded Investment	$ (2)	$ 0
Chapter 7 Bankruptcy | Home Equity
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	5	8
Pre-Modification Outstanding Recorded Investment	$ 245	$ 142
Post-Modification Outstanding Recorded Investment	243	133
Total Difference in Recorded Investment	$ (2)	$ (9)
Maturity date extension and interest rate reduction
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	0
Pre-Modification Outstanding Recorded Investment	$ 130	$ 0
Post-Modification Outstanding Recorded Investment	130	0
Total Difference in Recorded Investment	$ 0	$ 0
Maturity date extension and interest rate reduction | Home Equity
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	0
Pre-Modification Outstanding Recorded Investment	$ 130	$ 0
Post-Modification Outstanding Recorded Investment	130	0
Total Difference in Recorded Investment	$ 0	$ 0
Maturity Date Extension
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	6	2
Pre-Modification Outstanding Recorded Investment	$ 1,341	$ 851
Post-Modification Outstanding Recorded Investment	1,320	836
Total Difference in Recorded Investment	$ (21)	$ (15)
Maturity Date Extension | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	2	1
Pre-Modification Outstanding Recorded Investment	$ 625	$ 780
Post-Modification Outstanding Recorded Investment	605	765
Total Difference in Recorded Investment	$ (20)	$ (15)
Maturity Date Extension | Commercial Construction
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	0
Pre-Modification Outstanding Recorded Investment	$ 33	$ 0
Post-Modification Outstanding Recorded Investment	33	0
Total Difference in Recorded Investment	$ 0	$ 0
Maturity Date Extension | Residential Mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	1	0
Pre-Modification Outstanding Recorded Investment	$ 483	$ 0
Post-Modification Outstanding Recorded Investment	483	0
Total Difference in Recorded Investment	$ 0	$ 0
Maturity Date Extension | Home Equity
Financing Receivable, Modifications [Line Items]
Number of Loans | contract	2	1
Pre-Modification Outstanding Recorded Investment	$ 200	$ 71
Post-Modification Outstanding Recorded Investment	199	71
Total Difference in Recorded Investment	$ (1)	$ 0