Securities - Unrealized Loss Positions (Detail) $ in Thousands	Jun. 30, 2019 USD ($) Security	Dec. 31, 2018 USD ($) Security
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | Security	53	98
Less than 12 months, Fair Value	$ 983	$ 11,376
Less than 12 months, Unrealized Loss		(133)
12 months or more, Fair Value	34,705	52,962
12 months or more, Unrealized Loss	(316)	(1,557)
Fair Value, Total	35,688	64,338
Total Unrealized Loss	$ (316)	$ (1,690)
US Government Agencies and Mortgage Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | Security	45	54
Less than 12 months, Fair Value	$ 983	$ 2,911
Less than 12 months, Unrealized Loss		(22)
12 months or more, Fair Value	31,302	43,843
12 months or more, Unrealized Loss	(279)	(1,257)
Fair Value, Total	32,285	46,754
Total Unrealized Loss	$ (279)	$ (1,279)
State and Municipal Obligations
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | Security	8	39
Less than 12 months, Fair Value		$ 2,723
Less than 12 months, Unrealized Loss		(27)
12 months or more, Fair Value	$ 3,403	9,119
12 months or more, Unrealized Loss	(37)	(300)
Fair Value, Total	3,403	11,842
Total Unrealized Loss	$ (37)	$ (327)
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | Security		5
Less than 12 months, Fair Value		$ 5,742
Less than 12 months, Unrealized Loss		(84)
Fair Value, Total		5,742
Total Unrealized Loss		$ (84)