Securities - Summary of Debt Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 12,236	$ 38,416
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	41	138
Available-for-sale Securities, 12 Months or Longer, Fair Value	14,898	35,402
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	642	628
Available-for-sale Securities, Fair Value, Total	27,134	73,818
Available-for-sale Securities, Unrealized Losses, Total	683	766
Held for Investment
Held-to-maturity Securities, Less than 12 Months, Fair Value	119	1,016
Held-to-maturity Securities, Less than 12 Months, Unrealized Losses	1	5
Held-to-maturity Securities, 12 Months or Longer, Fair Value		3
Held-to-maturity Securities, Fair Value, Total	119	1,019
Held-to-maturity Securities, Unrealized Losses, Total	1	5
U.S. Federal Agencies [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	12,236	10,362
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	41	19
Available-for-sale Securities, 12 Months or Longer, Fair Value	2,184	2,700
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	19	19
Available-for-sale Securities, Fair Value, Total	14,420	13,062
Available-for-sale Securities, Unrealized Losses, Total	60	38
Asset backed Securities [Member]
Available for Sale
Available-for-sale Securities, 12 Months or Longer, Fair Value	12,714	12,714
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	623	606
Available-for-sale Securities, Fair Value, Total	12,714	12,714
Available-for-sale Securities, Unrealized Losses, Total	623	606
U.S. Treasuries [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value		8,999
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		10
Available-for-sale Securities, 12 Months or Longer, Fair Value		19,988
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses		3
Available-for-sale Securities, Fair Value, Total		28,987
Available-for-sale Securities, Unrealized Losses, Total		13
Mortgage Backed Securities [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value		15,165
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		64
Available-for-sale Securities, Fair Value, Total		15,165
Available-for-sale Securities, Unrealized Losses, Total		64
Held for Investment
Held-to-maturity Securities, 12 Months or Longer, Fair Value		3
Held-to-maturity Securities, Fair Value, Total		3
States and Political Subdivisions [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value		3,890
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		45
Available-for-sale Securities, Fair Value, Total		3,890
Available-for-sale Securities, Unrealized Losses, Total		45
Held for Investment
Held-to-maturity Securities, Less than 12 Months, Fair Value	119	1,016
Held-to-maturity Securities, Less than 12 Months, Unrealized Losses	1	5
Held-to-maturity Securities, Fair Value, Total	119	1,016
Held-to-maturity Securities, Unrealized Losses, Total	$ 1	$ 5

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