Securities - Summary of Gross Unrealized Losses and Fair Value of Available for Sale Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity, Gross Unrealized Losses, Total	$ 210	$ 597
Gross Unrealized Losses, Total	481	1,316
Gross Unrealized Losses, Less Than 12 Months	429	1,583
Fair Value, Less Than 12 Months	39,003	67,186
Gross Unrealized Losses, 12 Months Or More	262	330
Fair Value, 12 Months Or More	7,917	6,776
Gross Unrealized Losses, Total	691	1,913
Fair Value, Total	46,920	73,962
U.S. Treasury Security [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than 12 Months	1
Fair Value, Less Than 12 Months	997
Gross Unrealized Losses, Total	1
Fair Value, Total	997
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity, Gross Unrealized Losses, Less Than 12 Months	129	396
Held-to-maturity, Fair Value, Less Than 12 Months	6,869	8,602
Held-to-maturity, Gross Unrealized Losses, Total	129	396
Held-to-maturity, Fair Value, Total	6,869	8,602
Gross Unrealized Losses, Less Than 12 Months	35	98
Fair Value, Less Than 12 Months	6,464	6,402
Gross Unrealized Losses, Total	35	98
Fair Value, Total	6,464	6,402
Mortgage-Backed Securities of Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity, Gross Unrealized Losses, Less Than 12 Months		28
Held-to-maturity, Fair Value, Less Than 12 Months		2,018
Held-to-maturity, Gross Unrealized Losses, 12 Months Or More	81	173
Held-to-maturity, Fair Value, 12 Months Or More	3,534	3,621
Held-to-maturity, Gross Unrealized Losses, Total	81	201
Held-to-maturity, Fair Value, Total	3,534	5,639
Gross Unrealized Losses, Less Than 12 Months	210	589
Fair Value, Less Than 12 Months	20,136	27,243
Gross Unrealized Losses, Total	210	589
Fair Value, Total	20,136	27,243
Asset-Backed Securities of Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, 12 Months Or More	19	46
Fair Value, 12 Months Or More	1,213	1,266
Gross Unrealized Losses, Total	19	46
Fair Value, Total	1,213	1,266
State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than 12 Months	53	439
Fair Value, Less Than 12 Months	3,597	19,328
Gross Unrealized Losses, 12 Months Or More	19
Fair Value, 12 Months Or More	813
Gross Unrealized Losses, Total	72	439
Fair Value, Total	4,410	19,328
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than 12 Months	1	33
Fair Value, Less Than 12 Months	940	3,593
Gross Unrealized Losses, 12 Months Or More	143	111
Fair Value, 12 Months Or More	2,357	1,889
Gross Unrealized Losses, Total	144	144
Fair Value, Total	$ 3,297	$ 5,482