Investment Securities - Reconciliation of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Total securities, Available for Sale, Amortized Cost	$ 458,559	$ 455,055
Gross Unrealized Gains	6,076	5,620
Gross Unrealized Losses	(2,949)	(3,226)
Total securities, Available for Sale, Fair Value	461,686	457,449
US Treasury and Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Total securities, Available for Sale, Amortized Cost	100,385	94,466
Gross Unrealized Gains	419	261
Gross Unrealized Losses	(593)	(807)
Total securities, Available for Sale, Fair Value	100,211	93,920
Mortgage-Backed Securities, Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Total securities, Available for Sale, Amortized Cost	300,443	309,162
Gross Unrealized Gains	2,771	2,868
Gross Unrealized Losses	(1,815)	(2,075)
Total securities, Available for Sale, Fair Value	301,399	309,955
Mortgage-Backed Securities, Multifamily [Member]
Schedule of Available-for-sale Securities [Line Items]
Total securities, Available for Sale, Amortized Cost	10,277	4,973
Gross Unrealized Gains	11	3
Gross Unrealized Losses	(68)
Total securities, Available for Sale, Fair Value	10,220	4,976
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Total securities, Available for Sale, Amortized Cost	30,597	29,764
Gross Unrealized Gains	723	888
Gross Unrealized Losses	(232)	(133)
Total securities, Available for Sale, Fair Value	31,088	30,519
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total securities, Available for Sale, Amortized Cost	496	494
Gross Unrealized Gains	7	11
Total securities, Available for Sale, Fair Value	503	505
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total securities, Available for Sale, Amortized Cost	16,361	16,196
Gross Unrealized Gains	2,145	1,589
Gross Unrealized Losses	(241)	(211)
Total securities, Available for Sale, Fair Value	$ 18,265	$ 17,574

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Name Accounting Standards Codification

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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