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Minimum Regulatory Capital Requirements - Additional Information (Detail)
Dec. 31, 2020
Dec. 31, 2019
Jan. 01, 2019
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]      
Minimum ratio of capital to risk-weighted assets 8.00 8.00 8.0
Minimum ratio of capital to risk-weighted assets including capital conservation buffer     10.50%
Minimum leverage ratio calculated as ratio of Tier 1 capital to average quarterly assets 9.08 10.02 4.0
Common Equity Tier 1 Capital [Member]      
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]      
Minimum ratio of capital to risk-weighted assets     4.5
Capital conservation buffer     2.50%
Minimum ratio of capital to risk-weighted assets including capital conservation buffer     7.00%
Tier 1 Capital [Member]      
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]      
Minimum ratio of capital to risk-weighted assets     6.0
Minimum ratio of capital to risk-weighted assets including capital conservation buffer     8.50%