Fair Value Measurements - Schedule of Fair Value of Assets Measured on Nonrecurring Basis (Detail) - Fair Value, Measurements, Nonrecurring [Member] - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	$ 0
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets		$ 10,000
Level III [Member] | Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets		$ 10,000