Fair Value of Assets and Liabilities - Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($)	Dec. 31, 2020		Dec. 31, 2019
Assets
Interest-bearing deposits	$ 1,500,000
Fair Value Recurring [Member]
Assets
Interest-bearing deposits	1,500,000
Available for sale investment securities	46,792,000	[1]	$ 48,998,000	[2]
Total	48,292,000		48,998,000
Fair Value Recurring [Member] | Level 2 [Member]
Assets
Interest-bearing deposits	1,500,000
Available for sale investment securities	46,792,000	[1]	48,998,000	[2]
Total	$ 48,292,000		$ 48,998,000

[1] Total unrealized gains of $1,013, net of tax, was included in accumulated other comprehensive income (loss) for the twelve months ended December 31, 2020 related to these assets.

[2] Total unrealized gains of $1,081, net of tax, was included in accumulated other comprehensive income (loss) for the twelve months ended December 31, 2019 related to these assets.