Debt Securities - Additional Information (Detail) $ in Millions |
9 Months Ended | ||
---|---|---|---|
Sep. 30, 2021
USD ($)
security
|
Sep. 30, 2020
USD ($)
|
Dec. 31, 2020
USD ($)
|
|
Investments, Debt and Equity Securities [Abstract] | |||
Number of debt securities available for sale | security | 160 | ||
Number of debt securities available for sale in unrealized loss position | security | 82 | ||
Accrued interest receivables | $ | $ 2.8 | $ 3.7 | |
Accrued interest receivables write-off | $ | $ 0.0 | $ 0.0 |