Fair Value Measurements - Summary of Assets at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 82,108	$ 55,093
Mortgage backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	43,380	28,193
Government agencies [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	2,152	2,412
Corporate bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	36,576	24,488
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	82,108	55,093
Level 2 [Member] | Mortgage backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	43,380	28,193
Level 2 [Member] | Government agencies [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	2,152	2,412
Level 2 [Member] | Corporate bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 36,576	$ 24,488