Loans and Credit Quality (Additions To TDR During The Period) (Detail) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2015 USD ($) borrower		Jun. 30, 2014 USD ($) borrower		Jun. 30, 2015 USD ($) borrower	Jun. 30, 2014 USD ($) borrower
Accruing Interest [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		5		2		6	5
Recorded Investment, Pre-Modification	[1]	$ 13,761		$ 6,188		$ 16,155	$ 19,755
Recorded Investment, Post-Modification	[1]	13,480		6,188		15,874	19,755
Change in recorded investment due to principal paydown (advances) at time of modification		$ 281		$ 0		$ 281	$ 0
Accruing Interest [Member] | Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		4		2		5	4
Recorded Investment, Pre-Modification	[1]	$ 13,415		$ 6,188		$ 15,809	$ 19,329
Recorded Investment, Post-Modification	[1]	$ 13,134		$ 6,188		$ 15,528	$ 19,329
Accruing Interest [Member] | Commercial [Member] | Extension of maturity date [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		4		1		5	2
Recorded Investment, Pre-Modification	[1],[2]	$ 13,415		$ 3,550		$ 15,809	$ 3,750
Recorded Investment, Post-Modification	[1],[2]	$ 13,134		$ 3,550		$ 15,528	$ 3,750
Accruing Interest [Member] | Commercial [Member] | Other concession [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		0		1		0	2
Recorded Investment, Pre-Modification	[1],[3]	$ 0		$ 2,638		$ 0	$ 15,579
Recorded Investment, Post-Modification	[1],[3]	$ 0		$ 2,638		$ 0	$ 15,579
Accruing Interest [Member] | Commercial real estate [Member] | Other concession [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower						0	1
Recorded Investment, Pre-Modification	[1],[3]					$ 0	$ 426
Recorded Investment, Post-Modification	[1],[3]					$ 0	$ 426
Accruing Interest [Member] | Home equity [Member] | Extension of maturity date [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		1		0		1	0
Recorded Investment, Pre-Modification	[1],[2]	$ 346		$ 0		$ 346	$ 0
Recorded Investment, Post-Modification	[1],[2]	$ 346		$ 0		$ 346	$ 0
Non Accrual [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		8		6		14	12
Recorded Investment, Pre-Modification	[1]	$ 4,860		$ 2,152		$ 11,130	$ 3,467
Recorded Investment, Post-Modification	[1]	4,855		2,152		11,031	3,417
Change in recorded investment due to principal paydown (advances) at time of modification		$ 5	[1]	$ 0	[1]	$ 99	$ 50
Non Accrual [Member] | Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		5		2		6	4
Recorded Investment, Pre-Modification	[1]	$ 4,690		$ 97		$ 5,363	$ 553
Recorded Investment, Post-Modification	[1]	$ 4,690		$ 97		$ 5,356	$ 503
Non Accrual [Member] | Commercial [Member] | Extension of maturity date [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		4		0		4	0
Recorded Investment, Pre-Modification	[1],[2]	$ 2,583		$ 0		$ 2,583	$ 0
Recorded Investment, Post-Modification	[1],[2]	$ 2,583		$ 0		$ 2,583	$ 0
Non Accrual [Member] | Commercial [Member] | Other concession [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		1		2		2	4
Recorded Investment, Pre-Modification	[1],[3]	$ 2,107		$ 97		$ 2,780	$ 553
Recorded Investment, Post-Modification	[1],[3]	$ 2,107		$ 97		$ 2,773	$ 503
Non Accrual [Member] | Commercial real estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower						3	1
Recorded Investment, Pre-Modification	[1]					$ 5,520	$ 1,120
Recorded Investment, Post-Modification	[1]					$ 5,433	$ 1,120
Non Accrual [Member] | Commercial real estate [Member] | Extension of maturity date [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower						2	0
Recorded Investment, Pre-Modification	[1],[2]					$ 1,747	$ 0
Recorded Investment, Post-Modification	[1],[2]					$ 1,660	$ 0
Non Accrual [Member] | Commercial real estate [Member] | Other concession [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		0		1		1	1
Recorded Investment, Pre-Modification	[1],[3]	$ 0		$ 1,120		$ 3,773	$ 1,120
Recorded Investment, Post-Modification	[1],[3]	$ 0		$ 1,120		$ 3,773	$ 1,120
Non Accrual [Member] | Residential real estate [Member] | Other concession [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		0		1		0	3
Recorded Investment, Pre-Modification	[1],[3]	$ 0		$ 70		$ 0	$ 565
Recorded Investment, Post-Modification	[1],[3]	$ 0		$ 70		$ 0	$ 565
Non Accrual [Member] | Home equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		3		2		5	4
Recorded Investment, Pre-Modification	[1]	$ 170		$ 865		$ 247	$ 1,229
Recorded Investment, Post-Modification	[1]	$ 165		$ 865		$ 242	$ 1,229
Non Accrual [Member] | Home equity [Member] | Extension of maturity date [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		3		0		3	1
Recorded Investment, Pre-Modification	[1],[2]	$ 170		$ 0		$ 170	$ 114
Recorded Investment, Post-Modification	[1],[2]	$ 165		$ 0		$ 165	$ 114
Non Accrual [Member] | Home equity [Member] | Other concession [Member]
Financing Receivable, Modifications [Line Items]
Number of Borrowers | borrower		0		2		2	3
Recorded Investment, Pre-Modification	[1],[3]	$ 0		$ 865		$ 77	$ 1,115
Recorded Investment, Post-Modification	[1],[3]	$ 0		$ 865		$ 77	$ 1,115

[1] Represents amounts as of the date immediately prior to and immediately after the modification is effective.

[2] Extension of maturity date also includes loans renewed at an existing rate of interest that is considered a below market rate for that particular loan’s risk profile.

[3] Other concessions primarily include interest rate reductions, loan increases or deferrals of principal.