Annual report pursuant to Section 13 and 15(d)

Available-for-Sale Securities - Additional Information (Details)

v3.20.4
Available-for-Sale Securities - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]    
Allowance for credit losses on securities in unrealized loss position $ 0 $ 0
Sale of available-for-sale securities $ 0