Securities - Summary of Investments in an Unrealized Loss Position that were Temporarily Impaired (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Less than 12 months - Fair Value	$ 55,987	$ 66,073
Securities available for sale, 12 months or more - Fair Value	5,190	5,499
Securities available for sale, Total - Fair Value	61,177	71,572
Securities available for sale, Less than 12 months - Unrealized (Loss)	(933)	(1,429)
Securities available for sale, 12 months or more - Unrealized (Loss)	(188)	(208)
Total Unrealized (Loss)	(1,121)	(1,637)
Securities held to maturity, Less than 12 months - Fair Value	37,022	48,980
Securities held to maturity, 12 months or more - Fair Value	0	0
Securities held to maturity, Total - Fair Value	37,022	48,980
Securities held to maturity, Less than 12 months - Unrealized (Loss)	(460)	(708)
Securities held to maturity, 12 months or more - Unrealized (Loss)	0	0
Total Unrealized (Loss)	(460)	(708)
Total securities, Less than 12 months - Fair Value	93,009	115,053
Total securities, 12 months or more - Fair Value	5,190	5,499
Total securities, Total - Fair Value	98,199	120,552
Total securities, Less than 12 months - Unrealized (Loss)	(1,393)	(2,137)
Total securities, 12 months or more - Unrealized (Loss)	(188)	(208)
Total Unrealized (Loss)	(1,581)	(2,345)
U.S. Agency and Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Less than 12 months - Fair Value	52,461	60,943
Securities available for sale, 12 months or more - Fair Value	5,190	5,499
Securities available for sale, Total - Fair Value	57,651	66,442
Securities available for sale, Less than 12 months - Unrealized (Loss)	(797)	(1,249)
Securities available for sale, 12 months or more - Unrealized (Loss)	(188)	(208)
Total Unrealized (Loss)	(985)	(1,457)
Securities held to maturity, Less than 12 months - Fair Value	26,783	34,770
Securities held to maturity, 12 months or more - Fair Value	0	0
Securities held to maturity, Total - Fair Value	26,783	34,770
Securities held to maturity, Less than 12 months - Unrealized (Loss)	(351)	(483)
Securities held to maturity, 12 months or more - Unrealized (Loss)	0	0
Total Unrealized (Loss)	(351)	(483)
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Less than 12 months - Fair Value	3,526	5,130
Securities available for sale, Total - Fair Value	3,526	5,130
Securities available for sale, Less than 12 months - Unrealized (Loss)	(136)	(180)
Total Unrealized (Loss)	(136)	(180)
Securities held to maturity, Less than 12 months - Fair Value	8,755	12,724
Securities held to maturity, 12 months or more - Fair Value	0	0
Securities held to maturity, Total - Fair Value	8,755	12,724
Securities held to maturity, Less than 12 months - Unrealized (Loss)	(93)	(211)
Securities held to maturity, 12 months or more - Unrealized (Loss)	0	0
Total Unrealized (Loss)	(93)	(211)
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities held to maturity, Less than 12 months - Fair Value	1,484	1,486
Securities held to maturity, 12 months or more - Fair Value	0	0
Securities held to maturity, Total - Fair Value	1,484	1,486
Securities held to maturity, Less than 12 months - Unrealized (Loss)	(16)	(14)
Securities held to maturity, 12 months or more - Unrealized (Loss)	0	0
Total Unrealized (Loss)	$ (16)	$ (14)

Available for sale securities and held to maturity securities continuous unrealized loss position accumulated loss.

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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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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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