Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurement - Additional Information (Detail)

v3.21.1
Fair Value Measurement - Additional Information (Detail)
3 Months Ended 12 Months Ended
Mar. 31, 2021
Dec. 31, 2020
Mortgage Backed Securities [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Average contractual maturity period 21 years 17 years