Loans and Loans Held for Sale - Restructured Loans for Periods Stated (Detail)		3 Months Ended				6 Months Ended
		Jun. 30, 2015 USD ($) SecurityLoan		Jun. 30, 2014 USD ($) SecurityLoan		Jun. 30, 2015 USD ($) SecurityLoan		Jun. 30, 2014 USD ($) SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		7		7		27		19
Pre-Modification Outstanding Recorded Investment		$ 796,000	[1]	$ 233,000	[1]	$ 5,408,000	[2]	$ 2,042,000	[1]
Post-Modification Outstanding Recorded Investment		$ 796,000	[1]	229,000	[1]	5,381,000	[2]	2,019,000	[1]
Total Difference in Recorded Investment				$ (4,000)		$ (27,000)		$ (23,000)
Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		1	[3]			1		0
Pre-Modification Outstanding Recorded Investment		$ 400,000	[1],[3]			$ 400,000	[2]	$ 0	[2]
Post-Modification Outstanding Recorded Investment		$ 400,000	[1],[3]			400,000	[2]	0	[2]
Total Difference in Recorded Investment						$ 0		$ 0
Principal Forgiveness [Member] | Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		1				1		0
Pre-Modification Outstanding Recorded Investment		$ 400,000	[1]			$ 400,000	[2]	$ 0	[2]
Post-Modification Outstanding Recorded Investment		$ 400,000	[1]			$ 400,000	[2]	$ 0	[2]
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan				1		9		1
Pre-Modification Outstanding Recorded Investment				$ 129,000	[1]	$ 3,616,000	[2]	$ 129,000	[2]
Post-Modification Outstanding Recorded Investment				127,000	[1]	3,615,000	[2]	127,000	[2]
Total Difference in Recorded Investment				$ (2,000)		$ (1,000)		$ (2,000)
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan				1		2		1
Pre-Modification Outstanding Recorded Investment				$ 129,000	[1]	$ 2,851,000	[2]	$ 129,000	[2]
Post-Modification Outstanding Recorded Investment				127,000	[1]	$ 2,851,000	[2]	127,000	[2]
Total Difference in Recorded Investment				$ (2,000)				(2,000)
Principal Deferral [Member] | Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						6
Pre-Modification Outstanding Recorded Investment	[2]					$ 661,000		0
Post-Modification Outstanding Recorded Investment	[2]					$ 661,000		0
Principal Deferral [Member] | Construction Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						1
Pre-Modification Outstanding Recorded Investment	[2]					$ 104,000		0
Post-Modification Outstanding Recorded Investment	[2]					103,000		$ 0
Total Difference in Recorded Investment						$ (1,000)
Chapter 7 Bankruptcy [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		4		6		13	[4]	17	[4]
Pre-Modification Outstanding Recorded Investment		$ 171,000	[1]	$ 104,000	[1]	$ 316,000	[2],[4]	$ 894,000	[2],[4]
Post-Modification Outstanding Recorded Investment		$ 171,000	[1]	102,000	[1]	305,000	[2],[4]	873,000	[2],[4]
Total Difference in Recorded Investment				$ (2,000)		$ (11,000)	[4]	$ (21,000)	[4]
Chapter 7 Bankruptcy [Member] | Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	[4]					1		1
Pre-Modification Outstanding Recorded Investment	[2],[4]					$ 3,000		$ 287,000
Post-Modification Outstanding Recorded Investment	[2],[4]					1,000		286,000
Total Difference in Recorded Investment	[4]					$ (2,000)		$ (1,000)
Chapter 7 Bankruptcy [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan				1				5	[4]
Pre-Modification Outstanding Recorded Investment				$ 52,000	[1]			$ 329,000	[2],[4]
Post-Modification Outstanding Recorded Investment				$ 52,000	[1]			327,000	[2],[4]
Total Difference in Recorded Investment	[4]							$ (2,000)
Chapter 7 Bankruptcy [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		4		4		12	[4]	10	[4]
Pre-Modification Outstanding Recorded Investment		$ 171,000	[1]	$ 43,000	[1]	$ 313,000	[2],[4]	$ 269,000	[2],[4]
Post-Modification Outstanding Recorded Investment		$ 171,000	[1]	41,000	[1]	304,000	[2],[4]	251,000	[2],[4]
Total Difference in Recorded Investment				$ (2,000)		$ (9,000)	[4]	$ (18,000)	[4]
Chapter 7 Bankruptcy [Member] | Consumer Borrower [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan				1				1	[4]
Pre-Modification Outstanding Recorded Investment				$ 9,000	[1]			$ 9,000	[2],[4]
Post-Modification Outstanding Recorded Investment				$ 9,000	[1]			9,000	[2],[4]
Interest Rate Reduction and Maturity Date Extension [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						2
Pre-Modification Outstanding Recorded Investment	[2]					$ 225,000		0
Post-Modification Outstanding Recorded Investment	[2]					$ 225,000		$ 0
Interest Rate Reduction and Maturity Date Extension [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		2
Pre-Modification Outstanding Recorded Investment		$ 225,000
Post-Modification Outstanding Recorded Investment		$ 225,000
Maturity Date Extension [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						2		1
Pre-Modification Outstanding Recorded Investment	[2]					$ 851,000		$ 1,019,000
Post-Modification Outstanding Recorded Investment	[2]					836,000		1,019,000
Total Difference in Recorded Investment						$ (15,000)
Maturity Date Extension [Member] | Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						1
Pre-Modification Outstanding Recorded Investment	[2]					$ 780,000		0
Post-Modification Outstanding Recorded Investment	[2]					765,000		$ 0
Total Difference in Recorded Investment						$ (15,000)
Maturity Date Extension [Member] | Construction Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans								1
Pre-Modification Outstanding Recorded Investment	[2]							$ 1,019,000
Post-Modification Outstanding Recorded Investment	[2]							1,019,000
Maturity Date Extension [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						2
Pre-Modification Outstanding Recorded Investment	[2]					$ 225,000		0
Post-Modification Outstanding Recorded Investment	[2]					$ 225,000		0
Maturity Date Extension [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						1
Pre-Modification Outstanding Recorded Investment	[2]					$ 71,000		0
Post-Modification Outstanding Recorded Investment	[2]					$ 71,000		$ 0

[1] Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.

[2] Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.

[3] Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed.

[4] Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed.