Loans Receivable - Average Recorded Investment and Interest Income Recognized on Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 14,123	$ 13,699	$ 14,204	$ 13,387
Interest Income Recognized	126	184	253	378
Commercial Business Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	56		56
Interest Income Recognized			1
Residential Real Estate, Single Family [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,340	1,358	1,848	1,359
Interest Income Recognized		1	1	4
Residential Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		944		898
Interest Income Recognized		11		18
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	449	380	440	360
Interest Income Recognized	6	5	12	13
With No Related Allowance Recorded [Member] | Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,978	5,279	3,025	5,207
Interest Income Recognized	13	50	27	120
With No Related Allowance Recorded [Member] | Commercial Business Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment
Interest Income Recognized
With No Related Allowance Recorded [Member] | Residential Real Estate, Single Family [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,364	1,358	1,360	1,359
Interest Income Recognized		1	1	4
With No Related Allowance Recorded [Member] | Residential Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		944		898
Interest Income Recognized		11		18
With No Related Allowance Recorded [Member] | Consumer Home Equity [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	273	190	262	170
Interest Income Recognized	3	2	7	6
With No Related Allowance Recorded [Member] | Consumer Dealer Auto and RV Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	25	10	26	11
Interest Income Recognized		1	1	2
With an Allowance Recorded [Member] | Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	11,145	8,420	11,179	8,180
Interest Income Recognized	113	134	226	258
With an Allowance Recorded [Member] | Commercial Business Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	56		56
Interest Income Recognized			1
With an Allowance Recorded [Member] | Residential Real Estate, Single Family [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	976		488
Interest Income Recognized
With an Allowance Recorded [Member] | Residential Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment
Interest Income Recognized
With an Allowance Recorded [Member] | Consumer Home Equity [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	148	176	149	175
Interest Income Recognized	3	2	4	5
With an Allowance Recorded [Member] | Consumer Dealer Auto and RV Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	3	4	3	4
Interest Income Recognized